U.S. patent application number 09/725258 was filed with the patent office on 2002-01-24 for electronic image pickup equipment.
Invention is credited to Konishi, Hirokazu, Mihara, Shinichi, Miyauchi, Yuji, Watanabe, Masahito.
Application Number | 20020008920 09/725258 |
Document ID | / |
Family ID | 26592395 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020008920 |
Kind Code |
A1 |
Mihara, Shinichi ; et
al. |
January 24, 2002 |
Electronic image pickup equipment
Abstract
The object of the invention is to reduce the thickness of
electronic image pickup equipment as much as possible, using a
zooming mode having stable, high image-formation capabilities from
an object at infinity to a near-by object. The electronic image
pickup equipment comprises a zoom lens system comprising a
negative, first lens group G1, a positive, second lens group G2 and
a positive, third lens group G3. For zooming from the wide-angle
end to the telephoto end of the zoom lens system upon focused on an
object at infinity, the separation between G2 and G3 becomes wise.
By moving G3 toward the object side of the system, the system can
be focused on a nearer-by object. In the zoom lens system, the
second lens group G2 comprises one positive lens 2a, one negative
lens 2b and a lens subgroup 2c comprising at least one lens, and
the third lens group G3 comprises one positive lens. The zoom lens
system satisfies conditions with respect to the optical axis
distance from the image-side surface of the positive lens 2a to the
image-side surface of the negative lens 2b and the focal length
ratio in air between the positive lens 2a and the lens subgroup
2c.
Inventors: |
Mihara, Shinichi; (Tokyo,
JP) ; Miyauchi, Yuji; (Tokyo, JP) ; Watanabe,
Masahito; (Tokyo, JP) ; Konishi, Hirokazu;
(Tokyo, JP) |
Correspondence
Address: |
PILLSBURY WINTHROP LLP
1600 TYSONS BOULEVARD
MCLEAN
VA
22102
US
|
Family ID: |
26592395 |
Appl. No.: |
09/725258 |
Filed: |
November 29, 2000 |
Current U.S.
Class: |
359/684 ;
348/E5.028; 359/676; 359/689 |
Current CPC
Class: |
G02B 26/007 20130101;
G02B 15/143507 20190801; G02B 15/177 20130101 |
Class at
Publication: |
359/684 ;
359/689; 359/676 |
International
Class: |
G02B 015/14 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2000 |
JP |
2000-151461 |
Jul 31, 2000 |
JP |
2000-230495 |
Claims
What we claim is:
1. Electronic image pickup equipment including a zoom lens system
and an electronic image pickup device in the rear of said zoom lens
system comprising, in order from an object side of the zoom lens
system, a first lens group having negative refracting power, a
second lens group having positive refracting power and a third lens
group having positive refracting power, in which for zooming from a
wide angle end to a telephoto end of the zoom lens system upon
focused on an object point at infinity, a separation between the
second lens group and the third lens group becomes wide and which
can be focused at a nearer-by subject by moving the third lens
group toward the object side, wherein: said second lens group
comprises, in order from an object side thereof, one positive lens
2a, one negative lens 2b and a lens subgroup 2c comprising at least
one lens and said third lens group comprises one positive lens,
while the following conditions are
satisfied:0.04<t.sub.2N/t.sub.2<0.18
(1)-0.5<f.sub.2a/f.sub.2c<1.1 (2)where t.sub.2N is an optical
axis distance from an image-side surface of the positive lens 2a
located on the object side of the second lens group to an
image-side surface of the negative lens 2b in the second lens
group, t.sub.2 is an optical axis distance from an object-side
surface of the positive lens 2a located on the object side of the
second lens group to a surface located nearest to an image side of
the lens group 2c, and f.sub.2a, and f.sub.2c is a focal length in
air of the positive lens 2a located on the object side of the
second lens group, and the lens group 2c, respectively.
2. Electronic image pickup equipment including a zoom lens system
and an electronic image pickup device in the rear of said zoom lens
system comprising, in order from an object side of the zoom lens
system, a first lens group having negative refracting power, a
second lens group having positive refracting power and a third lens
group having positive refracting power, in which for zooming from a
wide angle end to a telephoto end of the zoom lens system upon
focused on an object point at infinity, a separation between the
second lens group and the third lens group becomes wide and which
can be focused at a nearer-by subject by moving the third lens
group toward the object side, wherein: said second lens group
comprises, in order from an object side thereof, one positive lens
2a, one negative lens 2b and a lens subgroup 2c consisting of one
lens and said third lens group comprises one positive lens, while
the following conditions are
satisfied:0.04<t.sub.2N/t.sub.2<0.18
(1)-0.5<f.sub.2a/f.sub.2c<1.1 (2)where t.sub.2N is an optical
axis distance from an image-side surface of the positive lens 2a
located on the object side of the second lens group to an
image-side surface of the negative lens 2b in the second lens
group, t.sub.2 is an optical axis distance from an object-side
surface of the positive lens 2a located on the object side of the
second lens group to a surface located nearest to an image side of
the lens group 2c, and f.sub.2a, and f.sub.2c is a focal length in
air of the positive lens 2a located on the object side of the
second lens group, and the lens group 2c, respectively.
3. The electronic image pickup equipment according to claim 1 or 2,
wherein said lens subgroup 2c in the said second lens group
comprises an aspherical surface, and said third lens group
comprises a zoom lens consisting only of a spherical surface or
comprising an aspherical surface conforming to the following
condition:abs(z)/L<1.5.times.10.su- p.-2 (3)where abs(z) is an
absolute value of an amount of a deviation of the aspherical
surface in the third lens group from a spherical surface having an
axial radius of curvature in an optical axis direction as measured
at a height of 0.35 L from the optical axis, and L is a diagonal
length of an effective image pickup plane.
4. The electronic image pickup equipment according to claim 1 or 2,
which conforms to the following
conditions:(R.sub.2cl+R.sub.2cr)/(R.sub.2cl-R.s- ub.2cr)<-0.4
(4)-1.1<(R.sub.31+R.sub.32)/(R.sub.31-R.sub.32)<1.5 (5)where
R.sub.2cl and R.sub.2cr are axial radii of curvature of the
surfaces in the image-side lens subgroup 2c in the second lens
group, which surfaces are located nearest to the object and image
sides, respectively, and R.sub.31 and R.sub.32 are axial radii of
curvatures of the first and second lens surfaces in the third lens
group, respectively, as counted from the object side.
5. The electronic image pickup equipment according to claim 1 or 2,
wherein said lens 2a and said lens 2b in said second lens group are
cemented together.
6. The electronic image pickup equipment according to claim 1 or 2,
which conforms to the following
condition:-1.5<{(R.sub.2a1+R.sub.2a2).multid-
ot.(R.sub.2b1-R.sub.2b2)}/{(R.sub.2a1-R.sub.2a2).multidot.(R.sub.2b1+R.sub-
.2b2)}<-0.6 (6)where R.sub.2a1 and R.sub.2a2 are axial radii of
curvature on the object and image sides, respectively, of the lens
2a in the second lens group, and R.sub.2b1 and R.sub.2b2 are axial
radii of curvature on the object and image sides, respectively, of
the lens 2b in the second lens group.
7. The electronic image pickup equipment according to claim 1 or 2,
which further comprises a zoom lens having an aspherical surface on
an object-side surface of said lens 2a in said second lens
group.
8. The electronic image pickup equipment according to claim 1 or 2,
wherein said first lens group comprises a zoom lens comprising, in
order from an object side thereof, a negative lens subgroup
comprising at most two negative lenses and a positive lens subgroup
comprising one positive lens, with at least one negative lens in
said negative lens subgroup including an aspherical surface, and
the following condition is
satisfied:-0.1<f.sub.W/R.sub.11<0.45 (7)where R.sub.11 is an
axial radius of curvature of the first lens surface in the first
lens group, as counted from the object side, and f.sub.W is a focal
length of the zoom lens system at a wide-angle end thereof upon
focused on an object point at infinity.
9. The electronic image pickup equipment according to claim 8,
which comprises a zoom lens conforming to the following
condition:0.13<d.sub- .NP/f.sub.W<1.0 (8)where d.sub.NP is an
axial air separation between the negative and positive lens
subgroups in the first lens group.
10. The electronic image pickup equipment according to claim 1 or
2, wherein said first lens group comprises a zoom lens comprising,
in order from an object side thereof, one positive lens, two
negative lens and one positive lens.
11. The electronic image pickup equipment according to claim 10,
which comprises a zoom lens conforming to the following
condition:0.75<R.sub- .14/L<3 (9)where R.sub.14 is an axial
radius of curvature of the fourth lens surface in the first lens
group, as counted from the object side, and L is a diagonal length
of an effective image pickup area of the electronic image pickup
device.
12. The electronic image pickup equipment according to claim 1 or
2, wherein said first lens group comprises a zoom lens comprising,
in order from an object side thereof, two negative lenses, one
positive lens and one negative lens.
13. The electronic image pickup equipment according to claim 1 or
2, wherein said first lens group comprises a zoom lens comprising,
in order from an object side thereof, one positive lens, one
negative lens and one positive lens, with any one of said positive
lenses comprising an aspherical surface and having a weak
refracting power, and the following condition is
satisfied:0<f.sub.W/f.sub.1P<0.3 (10)where f.sub.1P is a
focal length of the positive lens in the first lens group, which
lens comprises an aspherical surface and has a weak refracting
power, and f.sub.W is a focal length of the zoom lens system at a
wide-angle end upon focused on an object point at infinity.
14. The electronic image pickup equipment according to claim 1 or
2, wherein said first lens group comprises a zoom lens comprising,
in order from an object side thereof, one positive lens, one
negative meniscus lens and a cemented lens component consisting of
a negative lens and a positive lens.
15. The electronic image pickup equipment according to claim 1 or
2, wherein said first lens group, and said second lens group has a
total thickness conforming to the following
conditions.0.4<t.sub.1/L<2.2 (11)0.5<t.sub.2/L<1.5
(12)where t.sub.1 is an axial thickness of the first lens group
from a lens surface located nearest to an object side thereof to a
lens surface located nearest to an image side thereof, t.sub.2 is
an axial thickness of the second lens group from a lens surface
located nearest to an object side thereof to a lens surface located
nearest to an image side thereof, and L is a diagonal length of an
effective image pickup area of the electronic image pickup
device.
16. The electronic image pickup equipment according to claim 1 or
2, wherein between the electronic image pickup device in the rear
of said zoom lens system and the object side of said electronic
image pickup equipment there is provided a near-infrared sharp cut
coating having a transmittance of 80% or greater at 600 nm
wavelength and a transmittance of 10% or less at 700 nm
wavelength.
17. The electronic image pickup equipment according to claim 16,
wherein a complementary color mosaic filter is used as a color
filter for said image pickup device.
18. The electronic image pickup equipment according to claim 17,
wherein said complementary color mosaic filter comprises at least
four types of color filter elements, and is designed in such a
mosaic fashion that substantially the same number of filter
elements are located for each type and adjacent pixels do not
correspond to the same type of color filter elements.
19. The electronic image pickup equipment according to claim 17,
wherein said complementary color filter is made up of at least four
types of color filter elements having the following
characteristics: a green color filter G having a spectral strength
peak at a wavelength G.sub.p, a yellow color filter Y.sub.e having
a spectral strength peak at a wavelength Y.sub.p, a cyan color
filter C having a spectral strength peak at a wavelength C.sub.p,
and a magenta color filter M having peaks at wavelengths M.sub.p1
and M.sub.p2, provided that510 nm<G.sub.p<540 nm5
nm<Y.sub.p-G.sub.p<35 nm-100 nm<C.sub.p-G.sub.p<-5
nm430 nm<M.sub.p1<480 nm580 nm<M.sub.p2<640 nm
20. The electronic image pickup equipment according to claim 19,
wherein each of said green, yellow and cyan color filters has a
strength of 80% or greater at 530 nm wavelength with respect to its
spectral strength peak, and said magenta color filter has a
strength of 10% to 50% inclusive at 530 nm wavelength with respect
to its spectral strength peak.
21. The electronic image pickup equipment according to claim 1 or
2, wherein an optical low-pass filter located between said
electronic image pickup device and the object side of said
equipment has a total thickness conforming to the following
condition:0.15.times.10.sup.3<t.sub.LPF/a&-
lt;0.45.times.10.sup.3 (13)where t.sub.LPF is the total thickness
of said optical low-pass filter and a is a horizontal pixel pitch
of said electronic image pickup device.
22. The electronic image pickup equipment according to claim 1 or
2, wherein aperture size comprises a plurality of fixed apertures,
one out of which can be inserted in an optical path between a lens
surface in said first lens group, which surface is nearest to an
image side thereof, and a lens surface in said third lens group,
which surface is nearest to an object side thereof, and can be
replaced with another aperture, so that field illuminance can be
controlled.
23. The electronic image pickup equipment according to claim 22,
wherein some of said plurality of apertures contain therein a
medium having a transmittance of less than 80% with respect to 550
nm wavelength.
24. The electronic image pickup equipment according to claim 22,
wherein when control is carried out to obtain a light quantity
corresponding to such an F-number as to provide a/F-number<0.4
.mu.m where a is the horizontal pixel pitch of the electronic image
pickup device, the apertures contain therein a medium having a
transmittance of less than 80% with respect to 550 nm
wavelength.
25. The electronic image pickup equipment according to claim 22,
wherein some of said plurality of apertures contain optical
low-pass filters having varying frequency characteristics.
26. The electronic image pickup equipment according to claim 1 or
2, wherein said zoom lens system has a zoom ratio of 2.3 or
greater.
27. Electronic image pickup equipment including a zoom lens system
and an electronic image pickup device in the rear of said zoom lens
system comprising, in order from an object side of the zoom lens
system, a first lens group having negative refracting power, a
second lens group having positive refracting power and a third lens
group having positive refracting power, in which for zooming from a
wide angle end to a telephoto end of the zoom lens system upon
focused on an object point at infinity, a separation between the
second lens group and the third lens group becomes wide and which
can be focused at a nearer-by subject by moving the third lens
group toward the object side, wherein said second lens group
comprises two cemented lens components.
28. Electronic image pickup equipment including a zoom lens system
and an electronic image pickup device in the rear of said zoom lens
system comprising, in order from an object side of the zoom lens
system, a first lens group having negative refracting power, a
second lens group having positive refracting power and a third lens
group having positive refracting power, in which for zooming from a
wide angle end to a telephoto end of the zoom lens system upon
focused on an object point at infinity, a separation between the
second lens group and the third lens group becomes wide and which
can be focused at a nearer-by subject by moving the third lens
group toward the object side, wherein said second lens group
comprises one cemented lens component and one single lens
component.
29. The electronic image pickup equipment according to claim 27 or
28, wherein said first lens group comprises one or two positive
lenses and one or two or three negative lenses.
30. The electronic image pickup equipment according to any one of
claims 27 or 28, wherein between the electronic image pickup device
in the rear of said zoom lens system and the object side of the
electronic image pickup equipment there is provided a near-infrared
sharp cut coating having a transmittance of 80% or greater at 600
nm wavelength and a transmittance of 10% or less at 700 nm
wavelength.
Description
[0001] This application claims benefit of Japanese Application(s)
No. 2000-151461 filed in Japan on May 23, 2000 and No. 2000-230495
filed in Japan on Jul. 31, 2000, the contents of which are
incorporated by this reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to electronic image
pickup equipment, and more particularly to a video camera or
digital camera wherein its thickness in the depthwise direction is
reduced by making some contrivance for optical systems such as a
zoom lens system. In addition, the zoom lens system is designed to
be rear focused.
[0003] In recent years, digital cameras (electronic cameras)
attract public attention as next-generation cameras now superseding
24 mm.times.36 mm film (usually called Leica format) cameras. For
current digital cameras there are a wide range of categories from a
high-performance type for commercial use to a portable popular
type.
[0004] A chief object of the present invention is to achieve a
video or digital camera of the portable popular type category in
particular, which is reduced in depth dimensions while high image
quality is ensured.
[0005] The greatest bottleneck in reducing the depth dimensions of
a camera is the thickness of the surface, nearest to the object
side, of an optical system, especially a zoom lens system to an
image pickup plane. Recently, a so-called collapsible mount type of
lens barrel has gone mainstream, wherein an optical system is
driven out of a camera body for phototaking and the optical system
is housed in the camera body for carrying. However, the thickness
of the lens mount with the optical system housed therein varies
largely depending of the lens type used, the filters used or the
like. To obtain high specifications especially regarding zoom
ratios, F-number, etc., it is preferable to make use of a so-called
positive precedent type of zoom lens system wherein the lens group
located nearest to its object side has positive refracting power.
Even when the zoom lens system is housed in a lens mount, however,
it is impossible to reduce the thickness of a camera largely,
because the respective lens elements have some thicknesses with a
large dead space (see JP-A 11-258507). In this regard, a negative
precedent type of zoom lens system, especially a zoom lens system
comprising two or three lens groups is favorable. However, it is
still impossible to reduce the thickness of a camera largely, even
when the lens nearest to the object side is a positive lens. This
is because each lens group comprises a number of lens elements or
the lens elements are thick (see JP-A 11-52246). Some known
examples of the zoom lens system suitable for use with electronic
image pickup devices, having satisfcatory image-formation
capabilities inclusive of zoom ratios, field angles and F-numbers
and capable of having the smallest thickness of a lens mount with
the zoom lens system housed therein are disclosed in JP-A's
11-194274, 11-287953 and 2000-9997.
[0006] To make the first lens group thin, it is preferable to
locate an entrance pupil at a shallow position. To this end, on the
one hand, it is required to increase the magnification of the
second lens group. On the other hand, some considerable burdens are
placed on the second lens group. This does not only make it
difficult to keep the second lens group thin but also to make
correction for aberrations, resulting in an unacceptably increase
in the influence of fabrication errors. Thickness and size
reductions may be achieved by reducing image pickup device size. To
achieve the same number of pixels, however, it is required to
reduce pixel size and make up for sensitivity shortages by the
optical system. The same also holds for the influence of
diffraction.
[0007] To reduce the depth dimensions of a camera body, it is
preferable in view of a driving mechanism layout to make use of a
rear focusing mode wherein the movement of lenses for focusing is
carried out by a rear lens group rather than a front lens group. In
this case, however, it is required to make a selection from optical
systems less susceptible to aberration fluctuations in the rear
focusing mode.
SUMMARY OF THE INVENTION
[0008] In view of such problems with the prior art as explained
above, it is a primary object of the present invention to reduce
the thickness of electronic image pickup equipment as much as
possible by making selective use of a zoom mode or construction
having a compact yet simple mechanism layout and stable yet high
image-formation capabilities from an object at infinity to a
near-by object, for instance, a rear focusing mode having a reduced
number of lens elements, and making lens elements so thin that the
total thickness of each lens group can be reduced while the
selection of filters is taken into account.
[0009] According to the first aspect of the present invention, this
object is achieved by the provision of electronic image pickup
equipment including a zoom lens system and an electronic image
pickup device in the rear of said zoom lens system comprising, in
order from an object side of the zoom lens system, a first lens
group having negative refracting power, a second lens group having
positive refracting power and a third lens group having positive
refracting power, in which for zooming from a wide-angle end to a
telephoto end of the zoom lens system upon focused on an object
point at infinity, a separation between the second lens group and
the third lens group becomes wide and which can be focused at a
nearer-by subject by moving the third lens group toward the object
side, characterized in that:
[0010] said second lens group comprises, in order from an object
side thereof, one positive lens 2a, one negative lens 2b and a lens
subgroup 2c comprising at least one lens and said third lens group
comprises one positive lens, while the following conditions are
satisfied:
0.04<t.sub.2N/t.sub.2<0.18 (1)
-0.5 <f.sub.2a/f.sub.2c<1.1 (2)
[0011] where t.sub.2N is an axial distance from an image-side
surface of the positive lens 2a located on the object side of the
second lens group to an image-side surface of the negative lens 2b
in the second lens group, t.sub.2 is an optical axis distance from
an object-side surface of the positive lens 2a located on the
object side of the second lens group to a surface located nearest
to an image side of the lens subgroup 2c, and f.sub.2a, and
f.sub.2c is a focal length in air of the positive lens 2a located
on the object side of the second lens group, and the lens subgroup
2c, respectively.
[0012] According to the second aspect of the present invention,
there is provided electronic image pickup equipment including a
zoom lens system and an electronic image pickup device in the rear
of said zoom lens comprising, in order from an object side of the
zoom lens system, a first lens group having negative refracting
power, a second lens group having positive refracting power and a
third lens group having positive refracting power, in which for
zooming from a wide angle end to a telephoto end of the zoom lens
system upon focused on an object point at infinity, a separation
between the second lens group and the third lens group becomes wide
and which can be focused at a nearer-by subject by moving the third
lens group toward the object side, characterized in that:
[0013] said second lens group comprises, in order from an object
side thereof, one positive lens 2a, one negative lens 2b and a lens
group 2c consisting of one lens and said third lens group comprises
one positive lens, while the following conditions are
satisfied:
0.04<t.sub.2N/t.sub.2<0.18 (1)
-0.5<f.sub.2a/f.sub.2c<1.1 (2)
[0014] where t.sub.2N is an optical axis distance from an
image-side surface of the positive lens 2a located on the object
side of the second lens group to an image-side surface of the
negative lens 2b in the second lens group, t.sub.2 is an optical
axis distance from an object-side surface of the positive lens 2a
located on the object side of the second lens group to a surface
located nearest to an image side of the lens group 2c, and
f.sub.2a, and f.sub.2c is a focal length in air of the positive
lens 2a located on the object side of the second lens group, and
the lens subgroup 2c, respectively.
[0015] An account is now given of why the aforesaid arrangements
are used in the present invention and how they work.
[0016] The electronic image pickup equipment of the present
invention includes a zoom lens system comprising, in order from the
object side thereof, a first lens group having negative refracting
power, a second lens group having positive refracting power and a
third lens group having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the system upon focused
on an object point at infinity, the separation between the second
lens group and the third lens group becomes wide. By moving the
third lens group toward the object side of the system, the system
can be focused on a nearer-by subject. The second lens group
comprises, in order from the object side thereof, one positive lens
2a, one negative lens 2c and a lens subgroup 2c comprising at least
one lens including an aspherical surface, and the third lens group
comprises one positive lens.
[0017] Alternatively, the second lens group may comprise, in order
from the object side thereof, one positive lens 2a, one negative
lens 2b and a lens subgroup 2c consisting of one lens including an
aspherical surface, and the third lens group may comprise one
positive lens.
[0018] This requirement for the zoom lens system according to the
present invention is inevitable for reducing fluctuations of
off-axis aberrations including astigmatism with focusing by the
third lens group while the total thickness of the lens portion
during lens housing is kept thin.
[0019] For an electronic image pickup device, it is required to
reduce the angle of incident rays as much as possible. A positive
lens in a two-group zoom lens system of +-construction most
commonly used as a silver salt camera-oriented zoom lens system,
which positive lens is located nearest to the image side thereof,
is used as a third lens group designed to be independently movable
in such a way as to keep an exit pupil at a farther position. When
this third lens group is used for focusing purposes, aberration
fluctuations offer a problem. When asphericity is incorporated in
the third lens group in an amount larger than necessary, it is
required that astigmatism remaining at the first and second lens
groups be corrected by the third lens group so as to obtain an
aspheric effect. In this case, it is not preferable to move the
third lens group for focusing, because the correction of
astigmatism becomes out of balance. In order to carry out focusing
with the third lens group, it is therefore required to
substantially remove the astigmatism at the first and second lens
groups over all the zooming zone. For this reason, it is desired
that the third lens group be made up of a spherical element or an
element having a small amount of asphericity, an aperture stop be
located on the object side of the second lens group, and an
aspherical surface be used at a lens in the second lens group,
which lens is positioned nearest to the image side of the second
lens group and has a particular effect on off-axis aberrations. In
addition, since this type zoom lens system makes it difficult to
increase the diameter of the front lens, it is preferable to make
an aperture stop integral with the second lens group (as can be
seen from the examples, given later, wherein the aperture stop is
located just before the second lens group for integration
therewith). This arrangement is not only simple in mechanism but
also makes any dead space less likely to occur during lens housing,
with a reduced F-number difference between the wide-angle end and
the telephoto end.
[0020] In the present invention, the following conditions (1) and
(2) should be satisfied.
0.04<t.sub.2N/t.sub.2<0.18 (1)
-0.5<f.sub.2a/f.sub.2c<1.1 (2)
[0021] where t.sub.2N is the optical axis distance from the
image-side surface of the positive lens 2a located on the object
side of the second lens group to the image-side surface of the
negative lens 2b in the second lens group, t.sub.2 is the optical
axis distance from the object-side surface of the positive lens 2a
located on the object side of the second lens group to the surface
located nearest to the image side of the lens subgroup 2c, and
f.sub.2a, and f.sub.2c is the focal length in air of the positive
lens 2a located on the object side of the second lens group, and
the lens subgroup 2c, respectively.
[0022] Condition (1) gives a definition of t.sub.2N that is the
optical axis distance from the image-side surface of the positive
lens 2a located on the object side of the second lens group to the
image-side surface of the negative lens 2b in the second lens
group. Unless this site has a certain thickness, astigmatism cannot
perfectly be corrected. However, this thickness becomes an obstacle
to making each element of the optical system thin. Thus, the
astigmatism is corrected by introducing an aspherical surface in
the image-sides surface of the lens located on the image side.
Nonetheless, when the lower limit of 0.04 is not reached, the
astigmatism remains undercorrected. When the upper limit of 0.18 is
exceeded, the thickness becomes unacceptably large.
[0023] Condition (2) gives a definition of the focal length ratio
in air between the positive lens 2a on the object side of the
second lens group and the lens subgroup 2c. When the upper limit of
1.1 is exceeded, the principal points of the second lens group are
shifted to the image side; some dead space is likely to occur in
the rear of the second lens group when the system is in use,
resulting in an increase in the overall length of the system. To
make the system thin upon lens housing in this case, it is thus
necessary to use a more complicated or larger lens barrel
mechanism. Otherwise, it is impossible to make the thickness of the
lens barrel mechanism thin to a certain degree. When the lower
limit of -0.5 is not reached, correction of astigmatism becomes
difficult.
[0024] More preferably, conditions (1) and (2) should be:
0.05<t.sub.2N/t.sub.2<0.16 (1)'
-0.4<f.sub.2a/f.sub.2c<0.8 (2)'
[0025] Most preferably, conditions (1) and (2) should be:
0.06<t.sub.2N/t.sub.2<0.15 (1)"
-0.3<f.sub.2a/f.sub.2c<0.62 (2)"
[0026] As already mentioned, it s desired that the lens subgroup 2c
in the second lens group comprise an aspherical surface and the
third lens group consist only of a spherical surface or an
aspherical surface that satisfies the following condition:
abs(z)/L<1.5.times.10.sup.-2 (3)
[0027] Here abs(z) is the absolute value of the amount of a
deviation of the aspherical surface in the third lens group from a
spherical surface having an axial radius of curvature in the
optical axis direction as measured at a height of 0.35L from the
optical axis, and L is the diagonal length of an effective image
pickup plane.
[0028] Exceeding the upper limit of 1.5.times.10.sup.-2 to
condition (3) is not preferable, because astigmatism is largely out
of balance upon rear focusing with the third lens group.
[0029] More preferably, condition (3) should be:
abs(z)/L<1.5.times.10.sup.-3 (3)'
[0030] Most preferably, condition (3) should be:
abs(z)/L<1.5.times.10.sup.-4 (3)"
[0031] In addition, it is preferable to satisfy the following
conditions (4) and (5). This is because even when rear focusing is
introduced in the optical system while it is kept thin, various
aberrations such as astigmatism and chromatic aberrations remain
stable all over the zooming zone from an object at infinity to a
near-by object.
(R.sub.2cl+R.sub.2cr)/(R.sub.2cl-R.sub.2cr)<-0.4 (4)
-1.1<(R.sub.31+R.sub.32)/(R.sub.31-R.sub.32)<1.5 (5)
[0032] Here R.sub.2cl and R.sub.2cr are the axial radii of
curvature of the surfaces in the image-side lens subgroup 2c in the
second lens group, which surfaces are located nearest to the object
and image sides, respectively, and R.sub.31 and R.sub.32 are the
axial radii of curvatures of the first and second lens surfaces in
the third lens group, respectively, as counted from the object
side.
[0033] Conditions (4) and (5) give definitions of the shape factors
of the aspherical lens subgroup 2c of the second lens group, which
is located nearest to the image side thereof and the positive lens
in the third lens group. When the upper limit of 1.5 to condition
(5) is exceeded, fluctuations of astigmatism due to rear focusing
become too large, and the astigmatism is likely to becoming worse
with respect a near-by object point although the astigmatism may be
well corrected on an object point at infinity. When the upper limit
of -0.4 to condition (4) is exceeded and the lower limit of -1.1 to
condition (5) is not reached, the fluctuations of astigmatism due
to rear focusing are reduced; however, it is difficult to make
correction for aberrations on an object point at infinity.
[0034] More preferably, conditions (4) and (5) should be:
-10.0<(R.sub.2cl+R.sub.2cr)/(R.sub.2cl-R.sub.2cr)<-0.6
(4)'
-0.5<(R.sub.31+R.sub.32)/(R.sub.31-R.sub.32)<1.2 (5)'
[0035] When the lower limit of -10.0 to condition (4)' is not
reached, the fluctuations of astigmatism due to rear focusing
become large.
[0036] Most preferably, conditions (4) and (5) should be:
-5.0<(R.sub.2cl+R.sub.2cr)/(R.sub.2cl-R.sub.2cr)<-0.8
(4)"
0.1<(R.sub.31+R.sub.32)/(R.sub.31-R.sub.32)<1.0 (5)"
[0037] In the second lens group, the positive and negative lenses
located on its object side should preferably be cemented together,
because some considerable aberrations occur due to their relative
decentration. In addition, the second lens group comprises one
negative lens adjacent to both positive lenses, wherein the
negative lens is cemented to either one of the positive lenses. In
this case, the third lens group may comprise one positive lens
composed of only spherical surfaces.
[0038] It is here noted that when the lens subgroup 2c of the
second lens group comprises a single lens, the cemented lens
consisting of lenses 2a and 2b should preferably satisfy the
following condition (6):
-1.5<{(R.sub.2a1+R.sub.2a2).multidot.(R.sub.2b1-R.sub.2b2)}/{(R.sub.2a1-
-R.sub.2a2).multidot.(R.sub.2b1+R.sub.2b2)}<-0.6 (6)
[0039] Here R.sub.2a1 and R.sub.2a2 are the axial radii of
curvature on the object and image sides, respectively, of the lens
2a in the second lens group, and R.sub.2b1 and R.sub.2b2 are the
axial radii of curvature on the object and image sides,
respectively, of the lens 2b in the second lens group.
[0040] Condition (6) gives a definition of the shape factor ratio
between the lens elements (positive lens and negative lens) of the
cemented lens in the second lens group. Falling below the lower
limit of -1.5 to condition (6) is unfavorable for correction of
longitudinal chromatic aberration and exceeding the upper limit of
-0.6 is unfavorable for size reductions because the lens elements
become thick.
[0041] More preferably, condition (6) should be:
-1.3<{(R.sub.2a1+R.sub.2a2).multidot.(R.sub.2b1-R.sub.2b2)}/{(R.sub.2a1-
-R.sub.2a2).multidot.(R.sub.2b1+R.sub.2b2)}<-0.7 (6)'
[0042] Most preferably, condition (6) should be:
-1.2<{(R.sub.2a1+R.sub.2a2).multidot.(R.sub.2b1-R.sub.2b2)}/{(R.sub.2a1-
-R.sub.2a2).multidot.(R.sub.2b1+R.sub.2b2)}<-0.8 (6)"
[0043] A zoom lens system having a zoom ratio of 2.3 or greater, if
it satisfies the following conditions, can then make some
contribution to thickness reductions.
1.3<-.beta..sub.2t<2.1 (a)
1.6<f.sub.2/f.sub.W<3.0 (b)
[0044] Here .beta..sub.2t is the magnification of the second lens
group at the telephoto end (an object point at infinity), f.sub.2
is the focal length of the second lens group, and f.sub.W is the
focal length of the zoom lens system at the wide-angle end (an
object point at infinity).
[0045] Condition (a) gives a definition of the magnification
.beta..sub.2t of the second lens group at the telephoto end (when
the zoom lens system is focused on an object point at infinity).
The larger this absolute value, the easier it is to reduce the
diameter of the first lens group because it is possible to make
shallow the position of the entrance pupil at the wide-angle end,
and so the smaller the first lens group is. When the lower limit of
1.3 is not reached, it is difficult to satisfy thickness. When the
upper limit of 2.1 is exceeded, it is difficult to make correction
for various aberrations (spherical aberrations, coma and
astigmatism). Condition (b) gives a definition of the focal length
f.sub.2 of the second lens group. To reduce the thickness of the
second lens group itself, the focal length of the second lens group
should preferably be reduced as much as possible. In view of power
profile, however, this is unreasonable for correction of the
aberrations because the front principal point of the second lens
group is positioned on the object side while the rear principal
point of the first lens group is positioned on the image side. When
the lower limit of 1.6 is not reached, it is difficult to make
correction for spherical aberrations, coma, astigmatism, etc. When
the upper limit of 3.0 is exceeded, it is difficult to achieve
thickness reductions.
[0046] More preferably, conditions (a) and (b) should be:
1.4<-.beta..sub.2t<2.0 (a)'
1.8<f.sub.2/f.sub.W<2.7 (b)'
[0047] Most preferably, conditions (a) and (b) should be:
1.5<-.beta..sub.2t<1.9 (a)"
2.0<f.sub.2/f.sub.W<2.5 (b)"
[0048] Thus, thickness reductions are contradictory to correction
of aberrations, and so it is preferable to introduce an aspherical
surface in the positive lens in the second lens group, which
positive lens is positioned nearest to its object side. This
aspherical surface has a great effect on correction of spherical
aberrations and coma, so that astigmatism and longitudinal
chromatic aberration can favorably be corrected. Preferably in this
case, condition (6) or (6)' or (6)" should be satisfied as well
irrespective of the construction of the second lens group.
[0049] As already explained, when rear focusing is carried out with
the third lens group, correction of off-axis aberrations should
preferably be substantially completed with the first and second
lens groups all over the zooming zone. If the construction of the
first lens group is selected with the construction of the second
lens group in mind, it is then possible to substantially complete
the correction of off-axis aberrations with the first and second
lens groups all over the zooming zone. The then construction of the
first lens group is now explained.
[0050] The first embodiment of the first lens group comprises, in
order from the object side thereof, a negative lens subgroup
comprising up to two negative lenses and a positive lens subgroup
consisting of one positive lens. In the first embodiment, at least
one negative lens in the negative lens subgroup comprises an
aspherical surface and the following conditions (7) and (8) are
satisfied.
[0051] The second embodiment comprises, in order from the object
side thereof, one positive lens, two negative lenses and one
positive lens and optionally satisfies the following condition
(9).
[0052] The third embodiment of the first lens group comprises, in
order from the object side thereof, one positive lens, one negative
lens and one positive lens. In the third embodiment, either one of
the positive lenses comprises an aspherical surface and has a weak
refracting power and the following condition (10) is satisfied.
[0053] The fourth embodiment comprises, in order from the object
side thereof, two negative lenses, one positive lens and one
negative lens.
[0054] In the present invention, any one of the aforesaid four
embodiments should preferably be used for the first lens group. The
aforesaid conditions (7) through (10) are now explained.
-0.1<f.sub.W/R.sub.11<0.45 (7)
0.13<d.sub.NP/f.sub.W<1.0 (8)
0.75<R.sub.14/L<3 (9)
0<f.sub.W/f.sub.1P<0.3 (10)
[0055] Here R.sub.11 is the axial radius of curvature of the first
lens surface in the first lens group, as counted from the object
side, f.sub.W is the focal length of the zoom lens system at the
wide-angle end (when focused on an object point at infinity),
d.sub.NP is the axial air separation between the negative and
positive lens subgroups of the first lens group, R.sub.14 is the
axial radius of curvature of the fourth lens surface in the first
lens group, as counted from the object side, L is the diagonal
length of the effective image pickup area of the image pickup
device, f.sub.1P is the focal length of the positive lens in the
first lens group, which lens comprises an aspherical surface and
has a weak refracting power, and f.sub.W is the focal length of the
zoom lens system at the wide-angle end (when focused on an object
point at infinity).
[0056] Condition (7) gives a definition of the radius of curvature
of the first surface in the first embodiment of the first lens
group. It is preferable that distortion is corrected by introducing
the aspherical surface in the first lens group and astigmatism is
corrected by the remaining spherical component. Exceeding the upper
limit of 0.45 is unfavorable for correction of the astigmatism, and
when the lower limit of -0.1 is not reached, the distortion cannot
perfectly be corrected even by the aspherical surface.
[0057] Condition (8) gives a definition of the axial air separation
d.sub.NP between the negative lens subgroup and the positive lens
subgroup in the first embodiment of the first lens group. Exceeding
the upper limit of 1.0 may be favorable for correction of
astigmatism; however, this is contradictory to size reductions
because of an increase in the thickness of the first lens group.
When the lower limit of 0.13 is not reached, it is difficult to
make correction for astigmatism.
[0058] Condition (9) gives a definition of the axial radius of
curvature R.sub.14 of the fourth lens surface in the second
embodiment of the first lens group. This embodiment may be
favorable for satisfactory correction of astigmatism and
distortion; however, the first lens group tends to become thick. If
R.sub.14 is as large as possible, it is then possible to reduce the
thickness of the first lens group. Falling below the lower limit of
0.75 is not preferable because some excessive space is needed. When
the upper limit of 3 is exceeded, the first lens group rather
increases in diameter and thickness because it is lacking in
power.
[0059] Condition (10) gives a definition of the focal length
f.sub.1P of the positive lens in the third embodiment of the first
lens group, which lens comprises an aspherical surface and has a
weak refracting power. When the upper limit of 0.3 is exceeded, the
power of only one negative lens in the first lens group becomes too
strong to correct distortion and the concave surface becomes
hard-to-process because its radius of curvature becomes too small.
Falling below the lower limit of 0 is not preferable in view of
correction of astigmatism, because the aspherical surface
contributes to only correction of distortion.
[0060] More preferably, conditions (7), (8), (9) and (10) should
be:
-0.05<f.sub.W/R.sub.11<0.25 (7)'
0.3<d.sub.NP/f.sub.W<0.9 (8)'
0.98<R.sub.14/L<2.5 (9)'
0<f.sub.W/f.sub.1P<0.2 (10)'
[0061] Most preferably, conditions (7), (8), (9) and (10) should
be:
-0.03<f.sub.W/R.sub.11<0.15 (7)"
0.32<d.sub.NP/f.sub.W<0.8 (8)"
1<R.sub.14/L<2 (9)"
0<f.sub.W/f.sub.1P<0.1 (10)"
[0062] In the aforesaid second embodiment, the first lens group may
comprise, in order from its object side, one positive lens, one
negative meniscus lens and a cemented lens component consisting of
a negative lens and a positive lens. When the first lens group is
made up of four lenses, for instance, a positive lens, a negative
lens, a negative lens and a positive lens in this order or two
negative lenses, a positive lens and a negative lens in this order,
the relative decentration of the two lenses located on the image
side often incurs a deterioration in image-formation capabilities.
For improvements in centering capabilities, it is thus preferable
to cement these lenses together.
[0063] In addition, the total thickness of the first lens group,
and the second lens group should preferably satisfy the following
conditions.
0.4<t.sub.1/L<2.2 (11)
0.5<t.sub.2/L<1.5 (12)
[0064] Here t.sub.1 is the axial thickness of the first lens group
from the lens surface located nearest to its object side to the
lens surface located nearest to its image side, t.sub.2 is the
axial thickness of the second lens group from the lens surface
located nearest to its object side to the lens surface located
nearest to its image side, and L is the diagonal length of the
effective image pickup area of the image pickup device.
[0065] Conditions (11) and (12) give a definition of the total
thickness of the first lens group, and the second lens group,
respectively. Exceeding the respective upper limits of 2.2 and 1.5
is likely to form an impediment to size reductions. When the
respective lower limits of 0.4 and 0.5 are not reached, it is
difficult to set up appropriate paraxial relations or make
correction for various aberrations because it is required to
moderate the radius of curvature of each lens surface.
[0066] In view of marginal thickness and mechanism space, it is
here noted that the ranges of these conditions should preferably be
adjusted depending on the value of L.
[0067] To be more specific, it is desired to satisfy the following
conditions (11)' and (12)'.
[0068] Condition (11)':
When L.ltoreq.6.2 mm, 0.8<t.sub.1/L<2.2
When 6.2 mm<L.ltoreq.9.2 mm, 0.7<t.sub.1/L<2.0
When 9.2 mm<L, 0.6<t.sub.1/L<1.8
[0069] Condition (12)':
When L.ltoreq.6.2 mm, 0.5<t.sub.2/L<1.5
When 6.2 mm<L.ltoreq.9.2 mm, 0.4<t.sub.2/L<1.3
When 9.2 mm<L, 0.3<t.sub.2/L<1.1
[0070] According to the present invention, it is thus possible to
provide means for improving the image-formation capabilities of the
zoom lens system while the thickness of the lens mount is
reduced.
[0071] An account is now given of the conditions for making
filters, etc. thin. In electronic image pickup equipment, usually,
an infrared absorption filter having such a certain thickness as to
prevent incidence of infrared light on an image pickup plane is
inserted between an image pickup device and the object side of the
equipment. Here consider the case where this filter is replaced by
a coating that is substantially devoid of thickness. As a matter of
course, the equipment becomes thin by this amount, and there is a
spillover effect. When a near-infrared sharp cut coating having a
transmittance of at least 80% at 600 nm wavelength and at most 10%
at 700 nm wavelength is introduced between the image pickup device
in the rear of a zoom lens system and the object side of the
equipment, red transmittance is relatively higher than that of an
adsorption type, so that the tendency of bluish purple to change to
magenta--which is one defect of a CCD having a complementary color
mosaic filter--can be mitigated by gain control, thereby achieving
color reproduction comparable to that by a CCD having a primary
color filter.
[0072] On the other hand, a CCD with a complementary color filter
mounted thereon, because of its high transmitted light energy, is
higher in substantial sensitivity, and more favorable in
resolution, than a CCD with a primary color filter mounted thereon.
Thus, there is much merit in using the complementary color filter
on a CCD of miniature size. Another filter or an optical low-pass
filter, too, should preferably satisfy the following condition with
respect to its total thickness t.sub.LPF.
0.15.times.10.sup.3<t.sub.LPF/a<0.45.times.10.sup.3 (13)
[0073] Here a is the horizontal pixel pitch of an electronic image
pickup device.
[0074] To make an optical low-pass filter thin, too, is effective
for reducing the thickness of the lens mount. However, this is
generally not preferable because the effect of the low-pass filter
on moire reductions becomes slender. As the pixel pitch becomes
small, on the other hand, the contrast of frequency components
exceeding Nyquist threshold decreases under the influence of
diffraction by an image-formation lens system, so that the decrease
in the moire-reducing effect can be accepted to some degrees. For
instance, when use is made of three types of filter elements put
one upon another in the optical axis direction, each of which
elements has crystallographic axes in the azimuth directions of
horizontal (=0.degree.) and .+-.45.degree. upon projection on an
image plane, it is known that some effects on moire reductions are
achievable. Referring here to the specifications where the filter
becomes thinnest, it is known that the elements are shifted by
a.mu.m in the horizontal direction and by SQRT(1/2).times.a.mu.m in
the .+-.45.degree. direction. The then filter thickness amounts to
about [1+2.times.SQRT(1/2)].times.a/- 5.88 (mm) where SQRT means a
square root. This is just the specification where contrast is
reduced down to zero at a frequency corresponding to Nyquist
threshold.
[0075] When the film thickness is smaller than this by a few % to
several tens %, there is a contrast of the frequency corresponding
to Nyquist threshold. However, this contrast can be controlled by
the aforesaid influence of diffraction. Regarding other filter
specifications, for instance, when one or two filter elements are
used, too, it is preferable to conform to condition (13). When the
upper limit of 0.45.times.10.sup.3 is exceeded, the optical
low-pass filter becomes too thick to achieve thickness reductions.
When the lower limit of 0.15.times.10.sup.3 is not reached, moire
removal becomes insufficient. Still, it is required that a be 5
.mu.m or less.
[0076] When a is 4 .mu.m or less, it is preferable that
0.13.times.10.sup.3<t.sub.LPF/a<0.42.times.10.sup.3 (13)'
[0077] This is because the optical low-pass filter is more
susceptible to diffraction. The optical low-pass filter may then be
embodied as follows.
[0078] When the low-pass filter is made up of three low-pass filter
elements put one upon another and 4 .mu.m.ltoreq.a<5 .mu.m, it
is preferable that
0.3.times.10.sup.3<t.sub.LPF/a<0.4.times.10.sup.3 (13-1)
[0079] When the low-pass filter is made up of two low-pass filter
elements put one upon another and 4 .mu.m.ltoreq.a<5 .mu.m, it
is preferable that
0.2.times.10.sup.3<t.sub.LPF/a<0.28.times.10.sup.3 (13-2)
[0080] When the low-pass filter is made up of one low-pass filter
element and 4 .mu.m.ltoreq.a<5 .mu.m, it is preferable that
0.1.times.10.sup.3<t.sub.LPF/a<0.16.times.10.sup.3 (13-3)
[0081] When the low-pass filter is made up of three low-pass filter
elements put one upon another and a <4 .mu.m, it is preferable
that
0.25.times.10.sup.3<t.sub.LPF/a<0.37.times.10.sup.3
(13-4)
[0082] When the low-pass filter is made up of two low-pass filter
elements put one upon another and a <3 .mu.m, it is preferable
that
0.6.times.10.sup.3<t.sub.LPF/a<0.25.times.10.sup.3 (13-5)
[0083] When the low-pass filter is made up of one low-pass filter
element and a <4 .mu.m, it is preferable that
0.08.times.10.sup.3<t.sub.LPF/a<0.14.times.10.sup.3
(13-6)
[0084] When an image pickup device having a small pixel pitch is
used, image quality deteriorates under the influence of diffraction
due to stop-down. To avoid this, the present invention provides
electronic image pickup equipment, wherein aperture size comprises
a plurality of fixed apertures, one out of which can be inserted in
an optical path between a lens surface in the first lens group,
which surface is nearest to an image side thereof, and a lens
surface in the third lens group, which surface is nearest to an
object side thereof, and can be replaced with another aperture, so
that field illuminance can be controlled. Preferably in this
electronic image pickup equipment, some of said plurality of
apertures should contain therein media having a varying
transmittance of less than 80% with respect to 550 nm wavelength,
so that light quantity control can be achieved, and some should
contain therein media having a transmittance of 80% or greater with
respect to 550 nm.
[0085] Alternatively, when control is carried out to obtain a light
quantity corresponding to such an F-number as to provide a/F-number
<0.4 .mu.m, the apertures should preferably contain therein
media having a varying transmittance of less than 80% with respect
to 550 nm wavelength.
[0086] To put it another way, when control is carried out to obtain
a light quantity corresponding to such an effective F-number as to
provide F.sub.NO'>a/0.4 .mu.m where F.sub.NO' is an effective
F-number defined by F.sub.NO/T wherein F.sub.NO is an F-number
found from the focal length of the zoom lens system and the
diameter of an entrance pupil and T is an aperture transmittance at
550 nm and a is a horizontal pixel pitch of an electronic image
pickup device, it is preferable to insert an aperture containing
therein a medium having a transmittance T of less than 80% with
respect to 550 nm in a zoom lens optical path.
[0087] For instance, when there is a deviation from the aforesaid
range on the basis of the open aperture value, the medium may be
not used or a dummy medium having a transmittance of 91% or greater
with respect to 550 nm wavelength is used. In the aforesaid range,
light quantity control may be carried out by using a member such an
ND filter rather than decreasing the diameter of the aperture stop
to such a degree that the influence of diffraction manifests
itself.
[0088] Alternatively, optical low-pass filters with varying
frequency characteristics instead of ND filters may be inserted in
a plurality of apertures whose diameters are evenly reduced in
inversely proportional to the F-number. Since the deterioration due
to diffraction becomes large with stop-down, it is required that
the smaller the aperture diameter, the higher the frequency
characteristics of the optical filters be. The higher frequency
characteristics mean that the contrast of the spatial frequency of
the object image is kept higher than those of other spatial
frequencies. In other words, this means that the cutoff frequency
is high.
[0089] It is here noted that the zoom lens system of the present
invention can have a zoom ratio of 2.3 or greater. According to the
invention, it is further possible to achieve electronic image
pickup equipment comprising a zoom lens system having a zoom ratio
of 2.6 or greater.
[0090] Still other objects and advantages of the invention will in
part be obvious and will in part be apparent from the
specification.
[0091] The invention accordingly comprises the features of
construction, combinations of elements, and arrangement of parts
which will be exemplified in the construction hereinafter set
forth, and the scope of the invention will be indicated in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0092] FIG. 1 is a sectional schematic at the wide-angle end of
Example 1 of the zoom lens system used on the electronic image
pickup equipment according to the present invention upon focused on
an object point at infinity.
[0093] FIG. 2 is a sectional schematic, similar to FIG. 1, of the
Example 2 of the zoom lens system.
[0094] FIG. 3 is a sectional schematic, similar to FIG. 1, of the
Example 3 of the zoom lens system.
[0095] FIG. 4 is a sectional schematic, similar to FIG. 1, of the
Example 4 of the zoom lens system.
[0096] FIG. 5 is a sectional schematic, similar to FIG. 1, of the
Example 5 of the zoom lens system.
[0097] FIG. 6 is a sectional schematic, similar to FIG. 1, of the
Example 6 of the zoom lens system.
[0098] FIG. 7 is a sectional schematic, similar to FIG. 1, of the
Example 7 of the zoom lens system.
[0099] FIG. 8 is a sectional schematic, similar to FIG. 1, of the
Example 8 of the zoom lens system.
[0100] FIG. 9 is a sectional schematic, similar to FIG. 1, of the
Example 9 of the zoom lens system.
[0101] FIG. 10 is a sectional schematic, similar to FIG. 1, of the
Example 10 of the zoom lens system.
[0102] FIG. 11 is a sectional schematic, similar to FIG. 1, of the
Example 11 of the zoom lens system.
[0103] FIG. 12 is a sectional schematic, similar to FIG. 1, of the
Example 12 of the zoom lens system.
[0104] FIG. 13 is a sectional schematic, similar to FIG. 1, of the
Example 13 of the zoom lens system.
[0105] FIG. 14 is a sectional schematic, similar to FIG. 1, of the
Example 14 of the zoom lens system.
[0106] FIG. 15 is a sectional schematic, similar to FIG. 1, of the
Example 15 of the zoom lens system.
[0107] FIG. 16 is a sectional schematic, similar to FIG. 1, of the
Example 16 of the zoom lens system.
[0108] FIG. 17 is a sectional schematic, similar to FIG. 1, of the
Example 17 of the zoom lens system.
[0109] FIGS. 18(a), 18(b) and 18(c) are aberration diagrams of
Example 1 of the zoom lens system upon focused at infinity.
[0110] FIG. 19 is a graph illustrative of the transmittance
characteristics of one example of the near-infrared sharp cut
filter used herein.
[0111] FIG. 20 is a graph illustrative of the transmittance
characteristics of one example of the color filter located on the
exit surface side of the low-pass filter.
[0112] FIG. 21 is illustrative of one exemplary color filter
profile for the complementary mosaic filter.
[0113] FIG. 22 is a graph illustrative of one example of the
wavelength characteristics of the complementary mosaic filter.
[0114] FIG. 23 is a perspective schematic illustrative of part of
one embodiment of the electronic image pickup equipment according
to the present invention.
[0115] FIG. 24 is a perspective schematic illustrative of one
embodiment of the aperture stop portion used in each example.
[0116] FIG. 25 is a perspective schematic illustrative of details
of another embodiment of the aperture stop portion used in each
example.
[0117] FIG. 26 is a front perspective schematic illustrative of the
outside shape of a digital camera with the zoom lens system of the
invention incorporated therein.
[0118] FIG. 27 is a rear perspective schematic illustrative of the
digital camera of FIG. 26.
[0119] FIG. 28 is a sectional schematic illustrative of the digital
camera of FIG. 26.
[0120] FIG. 29 is a front perspective schematic illustrative of an
uncovered personal computer wherein the zoom lens system of the
present invention is incorporated as an objective optical
system.
[0121] FIG. 30 is a sectional schematic illustrative of the
phototaking optical system in the personal computer.
[0122] FIG. 31 is side schematic illustrative of the phototaking
optical system shown in FIG. 29.
[0123] FIGS. 32(a) and 32(b) are a front and a side schematic of
the portable telephone wherein the zoom lens system of the present
invention is incorporated as an objective optical system.
[0124] FIG. 32(c) is a sectional schematic illustrative of the
phototaking optical system used with the portable telephone.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0125] An account is now given of Examples 1 through 17 of the zoom
lens system used with the electronic image pickup equipment
according to the present invention. Shown in FIGS. 1 through 17 are
the sections at the wide-angle ends of Examples 1 through 17 upon
focused on an object point at infinity. In each drawing, the first
lens group is indicated by G1, the second lens group by G2, the
third lens group by G3, a near-infrared cut filter by FI, an
optical low-pass filter comprising filter elements put one upon
another by FL, a cover glass for an image pickup device or a CCD by
CG, and the image plane of the CCD by I. The near-infrared cut
filter FI, optical low-pass filter FL and cover glass CG located in
order from the object side of the image pickup equipment are fixed
between the third lens group G3 and the image plane I, with the
near-infrared cut filter FI and optical low-pass filter FL cemented
together. In Example 12, the near-infrared cut filter FI is not
used. In each drawing, a focusing group is shown by "focus" and the
direction of focusing on a near-by object is shown by an arrow.
[0126] Example 1 is directed to a zoom lens system which, as shown
in FIG. 1, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
wide-angle and telephoto ends. The second lens group G2 is moved
toward the object side and the third lens group G3 is slightly
moved toward the image side, so that the separation between the
second lens group G2 and the third lens group G3 becomes wide. For
focusing on a near-by subject, the third lens group G3 is driven
out toward the object side.
[0127] In Example 1, the first lens group G1 is composed of a
cemented lens consisting of a double-concave lens and a negative
meniscus lens convex on its object side and a positive meniscus
lens convex on its object side. The second lens group G2 is
composed of a stop, a cemented lens located in the rear of the stop
and consisting of a double-convex lens and a double-concave lens,
and a positive meniscus lens convex on its object side, said
double-convex lens defining a positive lens 2a, said double-concave
lens defining a negative lens 2b and said positive meniscus lens
defining a lens subgroup 2c. The third lens group G3 is composed of
one double-convex lens. Three aspherical surfaces are used, one for
the surface of the cemented lens in the first lens group G1, which
surface is located nearest to its image side, one for the surface
in the second lens group G2, which surface is located nearest to
its object side, and one for the surface in the second lens group
G2, which surface is located nearest to its image side.
[0128] Example 2 is directed to a zoom lens system which, as shown
in FIG. 2, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
wide-angle and telephoto ends. The second lens group G2 is moved
toward the object side and the third lens group G3 is fixed, so
that the separation between the second lens group G2 and the third
lens group G3 becomes wide. For focusing on a near-by subject, the
third lens group G3 is driven out toward the object side.
[0129] In Example 2, the first lens group G1 is composed of two
negative meniscus lenses, each convex on its object side, and a
positive meniscus lens convex on its object side. The second lens
group G2 is composed of a stop, a cemented lens located in the rear
of the stop and consisting of a double-convex lens and a
double-concave lens, and a positive meniscus lens convex on its
object side, said double-convex lens defining a positive lens 2a,
said double-concave lens defining a negative lens 2b and said
positive meniscus lens defining a lens subgroup 2c. The third lens
group G3 is composed of one double-convex lens. Two aspherical
surfaces are used, one for the object-side surface of the second
negative meniscus lens in the first lens group G1 and another for
the surface in the second lens group G2, which surface is located
nearest to its image side.
[0130] Example 3 is directed to a zoom lens system which, as shown
in FIG. 3, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
wide-angle and telephoto ends. The second lens group G2 is moved
toward the object side and the third lens group G3 is slightly
moved toward the image side, so that the separation between the
second lens group G2 and the third lens group G3 becomes wide. For
focusing on a near-by subject, the third lens group G3 is driven
out toward the object side.
[0131] In Example 3, the first lens group G1 is composed of a
double-concave lens, a negative meniscus lens convex on its object
side and a positive meniscus lens convex on its object side. The
second lens group G2 is composed of a stop, a cemented lens located
in the rear of the stop and consisting of a double-convex lens and
a double-concave lens, and a positive meniscus lens convex on its
object side, said double-convex lens defining a positive lens 2a,
said double-concave lens defining a negative lens 2b and said
positive meniscus lens defining a lens subgroup 2c. The third lens
group G3 is composed of one double-convex lens. Three aspherical
surfaces are used, one for the image-side surface of the
double-concave lens in the first lens group G1, one for the surface
in the second lens group G2, which surface is located nearest to
its object side, and one for the surface in the second lens group
G2, which surface is located nearest to its image side.
[0132] Example 4 is directed to a zoom lens system which, as shown
in FIG. 4, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
wide-angle and telephoto ends. The second lens group G2 is moved
toward the object side and the third lens group G3 is slightly
moved toward the image side, so that the separation between the
second lens group G2 and the third lens group G3 becomes wide. For
focusing on a near-by subject, the third lens group G3 is driven
out toward the object side.
[0133] In Example 4, the first lens group G1 is composed of a
double-concave lens, a negative meniscus lens convex on its object
side and a positive meniscus lens convex on its object side. The
second lens group G2 is composed of a stop, a cemented lens located
in the rear of the stop and consisting of a double-convex lens and
a double-concave lens, and a positive meniscus lens convex on its
object side, said double-convex lens defining a positive lens 2a,
said double-concave lens defining a negative lens 2b and said
positive meniscus lens defining a lens subgroup 2c. The third lens
group G3 is composed of one double-convex lens. Three aspherical
surfaces are used, one for the image-side surface of the
double-concave lens in the first lens group G1, one for the surface
in the second lens group G2, which surface is located nearest to
its object side, and one for the surface in the second lens group
G2, which surface is located nearest to its image side.
[0134] Example 5 is directed to a zoom lens system which, as shown
in FIG. 5, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
wide-angle and telephoto ends. The second lens group G2 is moved
toward the object side and the third lens group G3 is slightly
moved toward the image side, so that the separation between the
second lens group G2 and the third lens group G3 becomes wide. For
focusing on a near-by subject, the third lens group G3 is driven
out toward the object side.
[0135] In Example 5, the first lens group G1 is composed of a
double-convex lens, a negative meniscus lens convex on its object
side and a positive meniscus lens convex on its object side. The
second lens group G2 is composed of a stop, a cemented lens located
in the rear of the stop and consisting of a double-convex lens and
a double-concave lens, and a positive meniscus lens convex on its
object side, said double-convex lens defining a positive lens 2a,
said double-concave lens defining a negative lens 2b and said
positive meniscus lens defining a lens subgroup 2c. The third lens
group G3 is composed of one double-convex lens. Three aspherical
surfaces are used, one for the image-side surface of the
double-convex lens in the first lens group G1, one for the surface
in the second lens group G2, which surface is located nearest to
its object side, and one for the surface in the second lens group
G2, which surface is located nearest to its image side.
[0136] Example 6 is directed to a zoom lens system which, as shown
in FIG. 6, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
wide-angle and telephoto ends. The second lens group G2 is moved
toward the object side and the third lens group G3 is slightly
moved toward the image side, so that the separation between the
second lens group G2 and the third lens group G3 becomes wide. For
focusing on a near-by subject, the third lens group G3 is driven
out toward the object side.
[0137] In Example 6, the first lens group G1 is composed of a
planoconvex lens, a negative meniscus lens convex on its object
side and a positive meniscus lens convex on its object side. The
second lens group G2 is composed of a stop, a cemented lens located
in the rear of the stop and consisting of a double-convex lens and
a double-concave lens, and a positive meniscus lens convex on its
object side, said double-convex lens defining a positive lens 2a,
said double-concave lens defining a negative lens 2b and said
positive meniscus lens defining a lens subgroup 2c. The third lens
group G3 is composed of one double-convex lens. Three aspherical
surfaces are used, one for the image-side surface of the
planoconvex lens in the first lens group G1, one for the surface in
the second lens group G2, which surface is located nearest to its
object side, and one for the surface in the second lens group G2,
which surface is located nearest to its image side.
[0138] Example 7 is directed to a zoom lens system which, as shown
in FIG. 7, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the image side at the telephoto end than at the
wide-angle end of the zoom lens system. The second lens group G2 is
moved toward the object side and the third lens group G3 is first
moved toward the object side and then moved back toward the image
side, so that the separation between the second lens group G2 and
the third lens group G3 becomes wide. For focusing on a near-by
subject, the third lens group G3 is driven out toward the object
side.
[0139] In Example 7, the first lens group G1 is composed of a
positive meniscus lens convex on its object side, a negative
meniscus lens convex on its object side, a double-concave lens and
a positive meniscus lens convex on its object side. The second lens
group G2 is composed of a stop, a cemented lens located in the rear
of the stop and consisting of a planoconvex lens and a planoconcave
lens, and a double-convex lens, said planoconvex lens defining a
positive lens 2a, said planoconcave lens defining a negative lens
2b and said double-convex lens defining a lens subgroup 2c. The
third lens group G3 is composed of one double-convex lens. Two
aspherical surfaces are used, one for the surface in the second
lens group G2, which surface is located nearest to its object side,
and another for the object-side surface of the final double-convex
lens in the second lens group G2.
[0140] Example 8 is directed to a zoom lens system which, as shown
in FIG. 8, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the object side at the telephoto end than at the
wide-angle end of the zoom lens system. The second lens group G2 is
moved toward the object side and the third lens group G3 is first
moved toward the object side and then moved back toward the image
side, so that the separation between the second lens group G2 and
the third lens group G3 becomes wide. For focusing on a near-by
subject, the third lens group G3 is driven out toward the object
side.
[0141] In Example 8, the first lens group G1 is composed of a
negative meniscus lens convex on its object side and a positive
meniscus lens convex on its object side. The second lens group G2
is composed of a stop, a cemented lens located in the rear of the
stop and consisting of a positive meniscus lens convex on its
object side and a negative meniscus lens convex on its object side,
and a double-convex lens, said positive meniscus lens defining a
positive lens 2a, said negative meniscus lens defining a negative
lens 2b and said double-convex lens defining a lens subgroup 2c.
The third lens group G3 is composed of one double-convex lens.
Three aspherical surfaces are used, one for the surface in the
first lens group G1, which surface is located nearest to its object
side, one for the surface in the second lens group G2, which
surface is located nearest to its object side and one for the
object-side surface of the double-convex lens in the second lens
group G2.
[0142] Example 9 is directed to a zoom lens system which, as shown
in FIG. 9, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
telephoto and wide-angle ends of the zoom lens system. The second
lens group G2 is moved toward the object side and the third lens
group G3 is first moved toward the object side and then moved back
toward the image side, so that the separation between the second
lens group G2 and the third lens group G3 becomes wide. For
focusing on a near-by subject, the third lens group G3 is driven
out toward the object side.
[0143] In Example 9, the first lens group G1 is composed of a
positive meniscus lens convex on its object side, a negative
meniscus lens convex on its object side and a cemented lens
consisting of a double-concave lens and a positive meniscus lens
convex on its object side. The second lens group G2 is composed of
a stop, a cemented lens located in the rear of the stop and
consisting of a positive meniscus lens convex on its object side
and a negative meniscus lens convex on its object side, and a
double-convex lens, said positive meniscus lens defining a positive
lens 2a, said negative meniscus lens defining a negative lens 2b
and said double-convex lens defining a lens subgroup 2c. The third
lens group is composed of one double-convex lens. Two aspherical
surfaces are used, one for the surface in the second lens group G2,
which surface is located nearest to its object side, and one for
the object-side surface of the double-convex lens in the second
lens group G2.
[0144] Example 10 is directed to a zoom lens system which, as shown
in FIG. 10, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system to take substantially the same position at the
telephoto and wide-angle ends of the zoom lens system. The second
lens group G2 is moved toward the object side and the third lens
group G3 is first moved toward the object side and then moved back
toward the image side, so that the separation between the second
lens group G2 and the third lens group G3 becomes wide. For
focusing on a near-by subject, the third lens group G3 is driven
out toward the object side.
[0145] In Example 10, the first lens group G1 is composed of a
negative meniscus lens convex on its object side, a double-concave
lens and a cemented lens consisting of a double-convex lens and a
double-concave lens. The second lens group G2 is composed of a
stop, a cemented lens located in the rear of the stop and
consisting of a positive meniscus lens convex on its object side
and a negative meniscus lens convex on its object side, and a
positive meniscus lens convex on its object side, said positive
meniscus lens defining a positive lens 2a, said negative meniscus
lens defining a negative lens 2b and the final positive meniscus
lens defining a lens subgroup 2c. The third lens group is composed
of one double-convex lens. Three aspherical surfaces are used, one
for the surface of the cemented lens in the first lens group G1,
which surface is located nearest to its object side, one for the
surface in the second lens group G2, which surface is located
nearest to its object side, and one for the surface in the second
lens group G2, which surface is located nearest to its image
side.
[0146] Example 11 is directed to a zoom lens system which, as shown
in FIG. 11, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the image side at the telephoto end than at the
wide-angle end. The second lens group G2 is moved toward the object
side and the third lens group G3 is slightly moved toward the image
side, so that the separation between the second lens group G2 and
the third lens group G3 becomes wide. For focusing on a near-by
subject, the third lens group G3 is driven out toward the object
side.
[0147] In Example 11, the first lens group G1 is composed of a
double-convex lens, a negative meniscus lens convex on its object
side, a double-concave lens and a positive meniscus lens convex on
its object side. The second lens group G2 is composed of a stop, a
cemented lens located in the rear of the stop and consisting of a
double-convex lens and a double-concave lens, and a positive
meniscus lens convex on its object side, said double-convex lens
defining a positive lens 2a, said double-concave lens defining a
negative lens 2b and said positive meniscus lens defining a lens
subgroup 2c. The third lens group G3 is composed of one
double-convex lens. Two aspherical surfaces are used, one for the
surface in the second lens group G2, which surface is located
nearest to its object side, and another for the object-side surface
of the positive meniscus lens in the second lens group G2.
[0148] Example 12 is directed to a zoom lens system which, as shown
in FIG. 12, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the image side at the telephoto end than at the
wide-angle end. The second lens group G2 is moved toward the object
side and the third lens group G3 is slightly moved toward the image
side, so that the separation between the second lens group G2 and
the third lens group G3 becomes wide. For focusing on a near-by
subject, the third lens group G3 is driven out toward the object
side.
[0149] In Example 12, the first lens group G1 is composed of a
positive meniscus lens convex on its object side, a negative
meniscus lens convex on its object side, a planoconcave lens and a
positive meniscus lens convex on its object side. The second lens
group G2 is composed of a stop, a cemented lens located in the rear
of the stop and consisting of a double-convex lens and a
double-concave lens, and a positive meniscus lens convex on its
object side, said double-convex lens defining a positive lens 2a,
said double-concave lens defining a negative lens 2b and said
positive meniscus lens defining a lens subgroup 2c. The third lens
group G3 is composed of one double-convex lens. Two aspherical
surfaces are used, one for the surface in the second lens group G2,
which surface is located nearest to its object side, and another
for the image-side surface of the positive meniscus lens in the
second lens group G2.
[0150] Example 13 is directed to a zoom lens system which, as shown
in FIG. 13, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the image side at the telephoto end than at the
wide-angle end. The second lens group G2 is moved toward the object
side and the third lens group G3 is first moved toward the object
side and then moved back toward the image side, so that the
separation between the second lens group G2 and the third lens
group G3 becomes wide. For focusing on a near-by subject, the third
lens group G3 is driven out toward the object side.
[0151] In Example 13, the first lens group G1 is composed of a
negative meniscus lens convex on its object side, a double-concave
lens and a positive meniscus lens convex on its object side. The
second lens group G2 is composed of a stop, a cemented lens located
in the rear of the stop and consisting of a positive meniscus lens
convex on its object side and a negative meniscus lens convex on
its object side, and a cemented lens consisting of a double-convex
lens and a negative meniscus lens convex on its object side, said
positive meniscus lens defining a positive lens 2a, said negative
meniscus lens defining a negative lens 2b and said cemented lens
consisting of a double-convex lens and a negative meniscus lens
defining a lens subgroup 2c. The third lens group G3 is composed of
one double-convex lens. Two aspherical surfaces are used, one for
the image-side surface of the negative meniscus lens in the first
lens group G1 and another for the surface of the second cemented
lens in the second lens group G2, which surface is located nearest
to its object side.
[0152] Example 14 is directed to a zoom lens system which, as shown
in FIG. 14, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the object side at the telephoto end than at the
wide-angle end. The second lens group G2 is moved toward the object
side and the third lens group G3 is first moved toward the object
side and then moved back toward the image side, so that the
separation between the second lens group G2 and the third lens
group G3 becomes wide. For focusing on a near-by subject, the third
lens group G3 is driven out toward the object side.
[0153] In Example 14, the first lens group G1 is composed of two
negative meniscus lenses, each convex on its object side, and a
positive meniscus lens convex on its object side. The second lens
group G2 is composed of a stop, a double-convex lens located in the
rear of the stop, a double-concave lens and a positive meniscus
lens convex on its object side, said double-convex lens defining a
positive lens 2a, said double-concave lens defining a negative lens
2b and said positive meniscus lens defining a lens subgroup 2c. The
third lens group G3 is composed of one double convex lens. Two
aspherical surfaces are used, one for the image-side surface of the
first negative meniscus lens in the first lens group G1 and another
for the image-side surface of the positive meniscus lens in the
second lens group G2.
[0154] Example 15 is directed to a zoom lens system which, as shown
in FIG. 15, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the image side at the telephoto end than at the
wide-angle end. The second lens group G2 is moved toward the object
side and the third lens group G3 is first moved toward the object
side and then moved back toward the image side, so that the
separation between the second lens group G2 and the third lens
group G3 becomes wide. For focusing on a near-by subject, the third
lens group G3 is driven out toward the object side.
[0155] In Example 15, the first lens group G1 is composed of two
negative meniscus lenses, each convex on its object side, and a
positive meniscus lens convex on its object side. The second lens
group G2 is composed of a stop, a cemented lens located in the rear
of the stop and consisting of a double-convex lens and a
double-concave lens, and a cemented lens consisting of a negative
meniscus lens convex on its objet side and a positive meniscus lens
convex on its object side, said double-convex lens defining a
positive lens 2a, said double-concave lens defining a negative lens
2b and said cemented lens consisting of a negative meniscus lens
and a positive meniscus lens defining a lens subgroup 2c. The third
lens group is composed of one double-convex lens. Three aspherical
surfaces are used, one for the image-side surface of the negative
meniscus lens in the first lens group G1, one for the surface in
the second lens group G2, which surface is located nearest to its
object side, and one for the surface in the second lens group G2,
which surface is located nearest to its image side.
[0156] Example 16 is directed to a zoom lens system which, as shown
in FIG. 16, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the image side at the telephoto end than at the
wide-angle end. The second lens group G2 is moved toward the object
side and the third lens group G3 is first moved toward the object
side and then moved back toward the image side, so that the
separation between the second lens group G2 and the third lens
group G3 becomes wide. For focusing on a near-by subject, the third
lens group G3 is driven out toward the object side.
[0157] In Example 16, the first lens group G1 is composed of two
negative meniscus lenses, each convex on its object side, and a
positive meniscus lens convex on its object side. The second lens
group G2 is composed of a stop, a double-convex lens located in the
rear of the stop and a cemented lens consisting of a double-concave
lens and a positive meniscus lens convex on its object side, said
double-convex lens defining a positive lens 2a, said double-concave
lens defining a negative lens 2b and said positive meniscus lens
defining a lens subgroup 2c. The third lens group G3 is composed of
one double-convex lens. Three aspherical surfaces are used, one for
the image-side surface of the first negative meniscus lens in the
first lens group G1, one for the surface in the second lens group
G2, which surface is located nearest to its object side, and one
the surface in the second lens group G2, which surface is located
nearest to its image side.
[0158] Example 17 is directed to a zoom lens system which, as shown
in FIG. 17, comprises a first lens group G1 having negative
refracting power, a second lens group G2 having positive refracting
power and a third lens group G3 having positive refracting power.
For zooming from the wide-angle end to the telephoto end of the
zoom lens system upon focused on an object point at infinity, the
first lens group G1 is first moved toward the image side of the
zoom lens system and then moved back toward the object side of the
zoom lens system, so that the first lens group G1 is positioned
somewhat nearer to the image side at the telephoto end than at the
wide-angle end. The second lens group G2 is moved toward the object
side and the third lens group G3 is first moved toward the object
side and then moved back toward the image side, so that the
separation between the second lens group G2 and the third lens
group G3 becomes wide. For focusing on a near-by subject, the third
lens group G3 is driven out toward the object side.
[0159] In Example 17, the first lens group G1 is composed of a
negative meniscus lens convex on its object side and a positive
meniscus lens convex on its object side. The second lens group G2
is composed of a stop, a cemented lens located in the rear of the
stop and consisting of a double-convex lens and a double-concave
lens, and a cemented lens consisting of a negative meniscus lens
convex on its object side and a positive meniscus lens convex on
its object side, said double-convex lens defining a positive lens
2a, said double-concave lens defining a negative lens 2b and said
cemented lens consisting of a negative meniscus lens and a positive
meniscus lens defining a lens subgroup 2c. The third lens group G3
is composed of one double-convex lens. Three aspherical surfaces
are used, one for the image-side surface of the negative meniscus
lens in the first lens group G1, one for the surface in the second
lens group G2, which surface is located nearest to its object side,
and one the surface in the second lens group G2, which surface is
located nearest to its image side.
[0160] Set out below are numerical data on each example. Symbols
used hereinafter but not hereinbefore have the following
meanings.
[0161] f: the focal length of the zoom lens system,
[0162] .omega.: half field angle,
[0163] F.sub.NO: F-number,
[0164] FB: back focus,
[0165] WE: wide-angle end.
[0166] ST: intermediate settings,
[0167] TE: telephoto end,
[0168] r.sub.1, r.sub.2, . . . : the radius of curvature of each
lens surface,
[0169] d.sub.1, d.sub.2, . . . : the separation between adjacent
lens surfaces,
[0170] n.sub.d1, n.sub.d2, . . . : the d-line refractive index of
each lens, and
[0171] V.sub.d1, V.sub.d2, . . . : the Abbe number of each
lens.
[0172] Here let x denote an optical axis where the direction of
propagation of light is positive and y represent a direction
perpendicular to the optical axis. Then, aspherical configuration
is given by
x=(y.sup.2/r)/[1+{1-(K+1)(y/r).sup.2}.sup.1/2]+A.sub.4y.sup.4+A.sub.6y.sup-
.6+A.sub.8y.sup.8+A.sub.10y.sup.10
[0173] where r is the paraxial radius of curvature, K is a conical
coefficient, and A.sub.4, A.sub.6, A.sub.8 and A.sub.10 are the
fourth, sixth, eighth, and tenth aspherical coefficients,
respectively.
1 Example 1 r.sub.1 = -299.4763 d.sub.1 = 0.8000 n.sub.d1 = 1.80610
.nu..sub.d1 40.92 r.sub.2 = 10.7304 d.sub.2 = 0.8000 n.sub.d2 =
1.69350 .nu..sub.d2 = 53.21 r.sub.3 = 5.0005(Aspheric) d.sub.3 =
2.3163 r.sub.4 = 9.8142 d.sub.4 = 1.0491 n.sub.d3 = 21.84666
.nu..sub.d3 = 23.78 r.sub.5 = 24. 5391 d.sub.5 = (Variable) r.sub.6
= .infin.(Stop) d.sub.6 = 1.0000 r.sub.7 = 5.1442(Aspheric) d.sub.7
= 4.9417 n.sub.d4 = 1.80610 .nu..sub.d4 = 40.92 r.sub.8 = -24.5946
d.sub.8 = 0.5000 n.sub.d5 = 1.84666 .nu..sub.d5 = 23.78 r.sub.9 =
3.5926 d.sub.9 = 0.2907 r.sub.10 = 4.2678 d.sub.10 = 1.1213
n.sub.d6 = 1.69350 .nu..sub.d6 = 53.21 r.sub.11 = 17.4260(Aspheric)
d.sub.11 = (Variable) r.sub.12 = 32.3232 d.sub.12 = 1.3472 n.sub.d7
= 1.80610 .nu..sub.d7 = 40.92 r.sub.13 = 16.8384 d.sub.13 =
(Variable) r.sub.14 = .infin. d.sub.14 = 0.8000 n.sub.d8 = 1.51633
.nu..sub.d8 = 64.14 r.sub.15 = .infin. d.sub.15 = 1.5000 n.sub.d9 =
1.54771 .nu..sub.d9 = 62.84 r.sub.16 = .infin. d.sub.16 = 0.8000
r.sub.17 = .infin. d.sub.17 = 0.7500 n.sub.d10 = 1.51633
.nu..sub.d10 = 64.14 r.sub.18 = .infin. Aspherical Coefficients 3rd
surface K = 0 A.sub.4 = -9.7049 .times. 10.sup.-4 A.sub.6 = 1.6918
.times. 10.sup.-8 A.sub.8 = -1.9046 .times. 10.sup.-6 A.sub.10 = 0
7th surface K = 0 A.sub.4 = -3.2379 .times. 10.sup.-4 A.sub.6 =
-3.5165 .times. 10.sup.-7 A.sub.8 = -1.0605 .times. 10.sup.-6
A.sub.10 = 0 11th surface K = 0 A.sub.4 = 2.0613 .times. 10.sup.-3
A.sub.6 = 8.6770 .times. 10.sup.-5 A.sub.8 = 7.3857 .times.
10.sup.-6 A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f (mm)
4.50482 8.71981 12.89361 F.sub.NO 2.5014 3.5154 4.5000
.omega.(.degree.) 32.1 17.9 12.3 FB (mm) 1.2022 1.2022 1.2022
d.sub.5 13.21884 4.97007 2.00000 d.sub.11 2.16583 7.95914 13.39659
d.sub.13 0.76457 0.59671 0.59784 Example 2 r.sub.1 = 124.1886
d.sub.1 = 0.5000 n.sub.d1 = 1.80610 .nu..sub.d1 = 40.92 r.sub.2 =
6.4891 d.sub.2 = 0.2000 r.sub.3 = 8.8097(Aspheric) d.sub.3 = 0.5000
n.sub.d2 = 1.69350 .nu..sub.d2 = 53.21 r.sub.4 = 5.1613 d.sub.4 =
1.5167 r.sub.5 = 7.8189 d.sub.5 = 1.9968 n.sub.d3 = 1.84666
.nu..sub.d3 = 23.78 r.sub.6 = 22.4795 d.sub.6 = (Variable) r.sub.7
= .infin.(Stop) d.sub.7 = 1.0000 r.sub.8 = 5.7490 d.sub.8 = 3.2514
n.sub.d4 = 1.83400 .nu..sub.d4 = 37.16 r.sub.9 = -28.3433 d.sub.9 =
0.5000 n.sub.d5 = 1.84666 .nu..sub.d5 = 23.78 r.sub.10 = 4.4271
d.sub.10 = 0.0037 r.sub.11 = 3.8345 d.sub.11 = 2.1860 n.sub.d6 =
1.69350 .nu..sub.46 = 53.21 r.sub.12 = 9.6822(Aspheric) d.sub.12 =
(Variable) r.sub.13 = 28.5044 d.sub.13 = 1.6870 n.sub.d7 = 4.80610
.nu..sub.d7 = 40.92 r.sub.14 = -18.4888 d.sub.14 = 0.5000 r.sub.15
= .infin. d.sub.15 = 0.8000 n.sub.d8 = 1.51633 .nu..sub.d8 = 64.14
r.sub.16 = .infin. d16 = 1.5000 n.sub.d9 = 1.54771 .nu..sub.d9 =
62.84 r.sub.17 = .infin. d.sub.17 = 0.8000 r.sub.18 = .infin.
d.sub.18 = 0.7500 n.sub.d10 = 1.51633 .nu..sub.d10 = 64.14 r19 =
.infin. Aspherical Coefficients 3rd surface K = 0 A.sub.4 = 7.1162
.times. 10.sup.-4 A.sub.6 = 1.4779 .times. 10.sup.-5 A.sub.8 =
-6.2370 .times. 10.sup.-8 A.sub.10 = 2.8762 .times. 10.sup.-8 12th
surface K = 0 A.sub.4 = 4.1399 .times. 10.sup.-3 A.sub.6 = 1.4041
.times. 10.sup.-4 A.sub.8 = 4.6776 .times. 10.sup.-5 A.sub.10 =
-6.7224 .times. 10.sup.-7 Zooming Data (.infin.) WE ST TE f (mm)
4.50500 8.64043 12.89150 F.sub.NO 2.5359 3.4987 4.5000
.omega.(.infin.) 32.0 18.1 12.3 FB (mm) 1.2192 1.2192 1.2192
d.sub.6 13.05471 4.91856 2.00000 d.sub.12 3.13949 8.57782 14.14762
Example 3 r.sub.1 = -1.488 .times. 10.sup.-4 d.sub.1 = 0.8000
n.sub.d1 = 1.69350 .nu..sub.d1 = 53.21 r.sub.2 = 9.3799(Aspheric)
d.sub.2 = 0.3000 r.sub.3 = 10.2288 d.sub.3 = 0.8000 n.sub.d2 =
1.75700 .nu..sub.d2 = 47.82 r.sub.4 = 5.3486 d.sub.4 = 1.7182
r.sub.5 = 7.2124 d.sub.5 = 2.0519 n.sub.d3 = 1.84666 .nu..sub.d3 =
23.78 r.sub.6 = = 12.3788 d.sub.6 = (Variable) r.sub.7 =
.infin.(Stop) d.sub.7 = 1.0000 r.sub.8 = 4.3412(Aspheric) d.sub.8 =
3.0928 n.sub.d4 = 1.80610 .nu..sub.d4 = 40.92 r.sub.9 = -175.9817
d.sub.9 = = 0.5000 n.sub.d5 = 1.84666 .nu..sub.d5 = 23.78 r.sub.10
= 3.5171 d.sub.10 = 0.7411 r.sub.11 = 5.4392 d.sub.11= 1.5159
n.sub.d6 = 1.69350 .nu..sub.d6 = 53.21 r.sub.12 = 27.1420(Aspheric)
d.sub.12 = (Variable) r.sub.13 = 47.2987 d.sub.13 = 1.7503 n.sub.d7
= 1.80610 .nu..sub.d7 = 40.92 r.sub.14 = -14.9152 d.sub.14 =
(Variable) r.sub.15 = .infin. d.sub.15 = 0.8000 n.sub.d8 = 4.51633
.nu..sub.d8 = 64.14 r.sub.16 = .infin. d.sub.16 = 1.5000 n.sub.d9 =
1.54771 .nu..sub.d9 = 62.84 r.sub.17 = .infin. d.sub.17 = 0.8000
r.sub.18 = .infin. d.sub.18 = 0.7500 n.sub.d10 = 1.51633
.nu..sub.d10 = 64.14 r.sub.19 = .infin. Aspherical Coefficients 2nd
surface K = 0 A.sub.4 = -4.1467 .times. 10.sup.-4 A.sub.6 = -4.7647
.times. 10.sup.-6 A.sub.8 = -2.6213 .times. 10.sup.-8 A.sub.10 = 0
8th surface K = 0 A.sub.4 = -5.2950 .times. 10.sup.-4 A.sub.6 =
1.0863 .times. 10.sup.-7 A.sub.8 = -3.1802 .times. 10.sup.-6
A.sub.10 = 0 12th surface K = 0 A.sub.4 = 1.5348 .times. 10.sup.-3
A.sub.6 = 8.2051 .times. 10.sup.-5 A.sub.8 = -7.2915 .times.
10.sup.-9 A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f (mm)
4.50832 7.73017 12.89769 F.sub.NO 2.5349 3.2431 4.5000
.omega.(.degree.) 32.0 20.0 12.3 FB (mm) 1.2000 1.2000 1.2000
d.sub.6 12.95262 5.65324 2.00000 d.sub.12 1.68696 5.94052 13.18015
d.sub.14 1.18583 1.19589 0.57807 Example 4 r.sub.1 = -3.598 .times.
10.sup.-4 d.sub.1 = 0.8000 n.sub.d1 = 1.69350 .nu..sub.d2 = 53.21
r.sub.2 = 18.1592(Aspheric) d.sub.2 = 0.4930 r.sub.3 = 22.4692
d.sub.3 = 0.8000 n.sub.d2 = 1.74320 .nu..sub.d2 = 49.34 r.sub.4 =
5.3980 d.sub.4 = 1.5765 r.sub.5 = 7.2381 d.sub.5 = 1.7200 n.sub.d3
= 1.84666 .nu.d3 = 23.78 r.sub.6 = 13.8584 d.sub.6 = (Variable)
r.sub.7 = .infin.(Stop) d.sub.7 = 1.0000 r.sub.8 =
4.229112(Aspheric) d.sub.8 = 2.9761 n.sub.d4 = 1.80610 .nu..sub.d4
= 40.92 r.sub.9 = -1.215 .times. 10.sup.-4 d.sub.9 = 0.5000
n.sub.d5 = 1.84666 .nu..sub.d5 = 23.78 r.sub.10 = 3.2233 d.sub.10 =
0.6831 r.sub.11 = 5.4229 d.sub.11 = 1.4251 n.sub.d6 = 1.69350
.nu..sub.d6 = 53.21 r.sub.12 = 40.7916(Aspheric) d.sub.12 =
(Variable) r.sub.13 = 25.5987 d.sub.13 = 1.9952 n.sub.d7 = 1.80610
.nu..sub.d7 = 40.92 r.sub.14 = -16.8356 d.sub.14 = (Variable)
r.sub.15 = .infin. d.sub.15 = 0.8000 n.sub.d8 = 1.51633 .nu.d8 =
64.14 r.sub.16 = .infin. d.sub.16 = 1.5000 n.sub.d9 = 1.54771
.nu..sub.d9 = 62.84 r.sub.17 = .infin. d.sub.17 = 0.8000 r.sub.18 =
.infin. d.sub.18 = 0.7500 n.sub.d10 = 1.51633 .nu..sub.d10 = 64.14
Aspherical Coefficients 2nd surface K = 0 A.sub.4 = -3.1603 .times.
10.sup.-4 A.sub.6 = -3.9521 .times. 10.sup.-6 A.sub.8 = 6.0589
.times. 10.sup.-8 A.sub.10 = 0 8th surface K = 0 A.sub.4 = -5.1306
.times. 10.sup.-4 A.sub.6 = 1.8480 .times. 10.sup.-8 A.sub.8 =
-4.0730 .times. 10.sup.-6 A.sub.10 = 0 12th surface K = 0 A.sub.4 =
1.0356.times. 10.sup.-3 A.sub.6 = 2.4472 .times. 10.sup.-6 A.sub.8
= 4.4957 .times. 10.sup.9 A.sub.10 = 0 Zooming Data (.infin.) WE ST
TE f (mm) 4.52278 7.10855 13.03552 F.sub.NO 2.5133 3.1531 4.5000
.omega.(.degree.) 31.9 21.6 12.2 FB (mm) 1.2005 1.2005 1.2005
d.sub.6 13.53208 7.42223 2.00000 d.sub.12 2.14294 6.24423 14.00455
d.sub.14 0.84554 0.45979 0.24109 Example 5 r.sub.1 = 2.152 .times.
10.sup.5 d.sub.1 = 1.4495 n.sub.d1 = 1.693502 .nu..sub.d1 = 53.21
r.sub.2 = -2.558 .times. 10.sup.5 d.sub.2 = 0.2000 (Aspheric)
r.sub.3 = 0.0973 d.sub.3 = 0.8000 n.sub.d2 = 1.757002 .nu..sub.d2 =
47.82 r.sub.4 = 5.0935 d.sub.4 = 1.5384 r.sub.5 = 6.3074 d.sub.5 =
2.2638 n.sub.d3 = 1.84666 .nu..sub.d3 = 23.78 r.sub.6 = 9.3748
d.sub.6 = (Variable) r.sub.7 = .infin.(Stop) d.sub.7 = 1.0000
r.sub.8 = 4.1304(Aspheric) d.sub.8 = 2.5732 n.sub.d4 = -1.80610
.nu..sub.d4 = 40.92 r.sub.9 = -11.7751 d.sub.9 = 0.5000 n.sub.d5 =
4.76182 .nu..sub.d5 = 26.52 r.sub.10 = 3.1492 d.sub.10 = 0.7939
r.sub.11 = 4.8685 d.sub.11 = 1.4660 n.sub.d6 = 1.69350 .nu..sub.d6
= 53.21 r.sub.12 = 13.7926(Aspheric) d.sub.12 = (Variable) r.sub.13
= 24.8420 d.sub.13 = 1.8696 n.sub.d7 = 1.78590 .nu..sub.d7 = 44.20
r.sub.14 = -16.7264 d.sub.14 = (Variable) r.sub.15 = .infin.
d.sub.15 = 0.8000 n.sub.d8 = 1.51633 .nu..sub.d8 = 64.14 r.sub.16 =
.infin. d.sub.16 = 1.5000 n.sub.d9 = 4.54771 .nu..sub.d9 = 62.84
r.sub.17 = .infin. d.sub.17 = 0.8000 r.sub.18 = .infin. d.sub.18 =
0.7500 n.sub.d10 = 1.51633 .nu..sub.d10 = 64.14 r.sub.19 = .infin.
Aspherical Coefficients 2nd surface K = 0 A.sub.4 = -2.4509 .times.
10.sup.-4 A.sub.6 = 1.3879 .times. 10.sup.-6 A.sub.8 = 9.0581
.times. 10.sup.-10 A.sub.10 = 0 8th surface K = 0 A.sub.4 = -5.0677
.times. 10.sup.-4 A.sub.6 = -3.2077 .times. 10.sup.-5 A.sub.8 =
-8.7757 .times. 10.sup.-7 A.sub.10 = 0 12th surface K = 0 A.sub.4 =
1.7107 .times. 10.sup.-3 A.sub.6 = 1.1805 .times. 10.sup.-7 A.sub.8
= 8.2007 .times. 10.sup.-8 A.sub.10 = 0 Zooming Data (.infin.) WE
ST TE f (mm) 4.51447 8.62182 12.88959 F.sub.NO 2.5874 3.5287 4.5000
.omega.(.degree.) 32.0 18.1 12.3 FB (mm) 1.2090 1.2090 1.2090
d.sub.6 12.81499 4.92338 2.00000 d.sub.12 2.02134 7.44412 12.92512
d.sub.14 0.66769 0.59868 0.58837 Example 6 r.sub.1 = 300.0000
d.sub.1 = 1.5565 n.sub.d1 = 1.6935 .nu..sub.d1 = 53.21 r.sub.2 =
.infin.(Aspheric) d.sub.2 = 0.2000 r.sub.3 = 82.5564 d.sub.3 =
0.8000 n.sub.d2 = 1.74320 .nu..sub.d2 = 19.34 r.sub.4 = 5.1873
d.sub.4 = 1.4942 r.sub.5 = 6.3281 d.sub.5 = 2.2680 n.sub.d3=
1.84666 .nu..sub.d3 = 23.78 r.sub.6 = 9.2079 d.sub.6 = (Variable)
r.sub.7 .infin.(Stop) d.sub.7 = 1.0000 r.sub.8 = 4.0105(Aspheric)
d.sub.8 = 2.5184 n.sub.d4 = 1.80610 .nu..sub.d4 = 40.92 r.sub.9 =
-11.4735 d.sub.9 = 0.5000 n.sub.d5 = = 1.76182 .nu..sub.d5 = 26.52
r.sub.10 = 3.0569 d.sub.10 = 0.9411 r.sub.11 = 5.5852 d.sub.11 =
1.5226 n.sub.d6 = 1.69350 .nu..sub.d6 = 53.21 r.sub.12 =
21.9403(Aspheric) d.sub.12 = (Variable) r.sub.13 = 24.5302 d.sub.13
= 1.8257 n.sub.d7 = 1.78590 .nu..sub.d7 = 44.20 r.sub.14 = -17.1746
d.sub.14 = (Variable) r.sub.15 = .infin. d.sub.15 = 0.8000 n.sub.d8
= 1.51633 .nu..sub.d8 = 64.14 r.sub.16 = .infin. d.sub.16 = 1.5000
n.sub.d9 = 1.54771 .nu..sub.d9 = 62.84 r.sub.17 = .infin. d.sub.17
= 0.8000 r.sub.18 = .infin. d.sub.18 = 0.7500 n.sub.d10 = 1.51633
.nu..sub.d10 = 64.14 r.sub.19 = .infin. Aspherical Coefficients 2nd
surface K = 0 A.sub.4 = -2.2492 .times. 10.sup.-4 A.sub.6 = 1.2214
.times. 10.sup.-6 A.sub.8 = 9.4346 .times. 10.sup.-10 A.sub.10 = 0
8th surface K = 0 A.sub.4 = -6.5411 .times. 10.sup.-4 A.sub.6 =
-2.8593 .times. 10.sup.-6 A.sub.8 = -2.2330 .times. 10.sup.-6
A.sub.10 = 0 12th surface K = 0 A.sub.4 = 9.4936 .times. 10.sup.-4
A.sub.6 = 1.5574 .times. 10.sup.-5 A.sub.8 = 7.8767 .times.
10.sup.-10 A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f (mm)
4.51498 8.60896 12.88808 F.sub.NO 2.5879 3.5446 4.5000
.omega.(.degree.) 32.0 18.1 12.3 FB (mm) 1.2088 1.2088 1.2088
d.sub.6 12.82458 5.03634 2.00000 d.sub.12 1.66703 7.33800 12.75814
d.sub.14 0.84088 0.59964 0.58685 Example 7 r.sub.1 = 23.0267
d.sub.1 = 2.3000 n.sub.d1 = 1.83400 .nu..sub.d1 = 37.16 r.sub.2 =
61.6747 d.sub.2 = 0.4000 r.sub.3 = 15.9771 d.sub.3 = 0.7000
n.sub.d2 = 1.80610 .nu..sub.d2 = 40.92 r.sub.4 = 5.5000 d.sub.4 =
3.2000 r.sub.5 = -71.2824 d.sub.5 = 0.7000 n.sub.d3 = 1.77250
.nu..sub.d3 = 49.60 r.sub.6 = 10.6103 d.sub.6 = 0.5000 r.sub.7 =
8.4732 d.sub.7 = 1.9000 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.8 = 19.1024 d.sub.8 = (Variable) r.sub.9 = .infin.(Stop)
d.sub.9 = 1.2000 r.sub.10 = 4.2893(Aspheric) d.sub.10 = 2.5000
n.sub.d5 = 1.80610 .nu..sub.d5 = 40.92 r.sub.11 = .infin. d.sub.11
= 0.7000 n.sub.d6 = 1.78470 .nu..sub.d6 = 26.29 r.sub.12 = 3.2649
d.sub.12 = 0.8000 r.sub.13 = 6.1863(Aspheric) d.sub.13 = 1.8000
n.sub.d7 = 1.69350 .nu..sub.d7 = 53.21 r.sub.14 = 176.5384 d.sub.14
= (Variable) r.sub.15 = 15.9331 d.sub.15 = 2.0000 n.sub.d8 =
1.48749 .nu..sub.d8 = 70.23 r.sub.16 = 27.9214 d.sub.16 =
(Variable) r.sub.17 = .infin. d.sub.17 = 0.8000 n.sub.d9 = 1.51633
.nu..sub.d9 = 64.14 r.sub.18 = .infin. d.sub.18 = 1.5000 n.sub.d10
= 1.54771 .nu..sub.d10 = 62.84 r.sub.19 = .infin. d.sub.19 = 0.8000
r.sub.20 = .infin. d.sub.20 = 0.7500 n.sub.d11 = 1.51633
.nu..sub.d11 = 64.14 r.sub.21 = .infin. Aspherical Coefficients
10th surface K = 0 A.sub.4 = -3.6659 .times. 10.sup.-4 A.sub.6 =
-4.1952 .times. 10.sup.-5 A.sub.8 = -1.6473 .times. 10.sup.-7
A.sub.10 = 0 13th surface K = 0 A.sub.4 = -4.8390 .times. 10.sup.-4
A.sub.6 = -1.3717 .times. 10.sup.-7 A.sub.8 = 8.2327 .times.
10.sup.-6 A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f (mm)
4.50001 8.69997 12.89995 F.sub.NO 2.6837 3.5405 4.4888
.omega.(.degree.) 31.9 17.8 12.2 FB (mm) 1.2000 1.2000 1.2000
d.sub.8 12.81554 4.21755 1.50000 d.sub.14 2.47460 6.96240 12.52366
d.sub.16 0.88665 1.49525 1.37807 Example 8 r.sub.1 =
20.9239(Aspheric) d.sub.1 = 0.5000 n.sub.d1 = 4.69350 .nu..sub.d1 =
53.21 r.sub.2 = 4.8243 d.sub.2 = 3.5000 r.sub.3 = 6.2574 d.sub.3 =
1.7050 n.sub.d2 = 1.84666 .nu..sub.d2 = 23.78 r.sub.4 = 6.9719
d.sub.4 = (Variable) r.sub.5 = .infin.(Stop) d.sub.5 = 1.2000
r.sub.6 = 4.4208(Aspheric) d.sub.6 = 1.9988 n.sub.d3 = 4.80610
.nu..sub.d3 = 40.92 r.sub.7 = 50.0000 d.sub.7 = 0.5000 n.sub.d4 =
1.80518 .nu..sub.d4 = 25.42 r.sub.8 = 3.8298 d.sub.8 = 0.5000
r.sub.9 = 10.5816(Aspheric) d.sub.9 = 1.5384 n.sub.d5 = 1.69350
.nu..sub.d5 = 53.21 r.sub.10 = -29.2700 d.sub.10 = (Variable)
r.sub.11 = 10.3884 d.sub.11 = 2.4081 n.sub.d6 = 1.48749 .nu..sub.d6
= 70.23 r.sub.12 = -26.9384 d.sub.12 = (Variable) r.sub.13 =
.infin. d.sub.13 = 0.8000 n.sub.d7 = 1.51633 .nu..sub.d7 = 64.14
r.sub.14 = .infin. d.sub.14 = 1.5000 n.sub.d8 = 1.54771 .nu..sub.d8
= 62.84 r.sub.15 = .infin. d.sub.15 = 0.8000 r.sub.16 = .infin.
d.sub.16 = 0.7500 n.sub.d9 = 1.51633 .nu..sub.d9 = 64.14 Aspherical
Coefficients 1st surface K = 0 A.sub.4 = 3.3003 .times. 10.sup.-4
A.sub.6 = -8.0541 .times. 10.sup.-7 A.sub.8 = 1.0236 .times.
10.sup.-7 A.sub.10 = 0 6th surface K = 0 A.sub.4 = -3.2647 .times.
10.sup.-4 A.sub.6 = -2.0657 .times. 10.sup.-5 A.sub.8 = -1.2929
.times. 10.sup.-6 A.sub.10 = 0 9th surface K = 0 A.sub.4 = -4.6010
.times. 10.sup.-4 A.sub.6 = -5.8571 .times. 10.sup.-6 A.sub.8 =
2.1198 .times. 10.sup.-6 A.sub.10 = 0 Zooming Data (.infin.) WE ST
TE f (mm) 4.50050 8.68964 12.89995 F.sub.NO 2.5948 3.4651 4.5341
.omega.(.degree.) 29.1 16.1 11.0 FB (mm) 1.2092 1.2092 1.2092
d.sub.4 12.53354 3.58255 1.50000 d.sub.10 2.53628 8.42336 16.33318
d.sub.12 1.50721 2.01017 0.95839 Example 9 r.sub.1 = 11.7272
d.sub.1 = 1.7000 n.sub.d1 = 1.74100 .nu..sub.d1 = 52.64 r.sub.2 =
25.6361 d.sub.2 = 0.2000 r.sub.3 = 10.1939 d.sub.3 = 0.7000
n.sub.d2 = 1.83400 .nu..sub.d2 = 37.16 r.sub.4 = 3.9946 d.sub.4 =
2.6000 r.sub.5 = -13.0723 d.sub.5 = 0.7000 n.sub.d3 = 1.51633
.nu..sub.d3 = 64.14 r.sub.6 = 4.5840 d.sub.6 = 2.4000 n.sub.d4 =
1.80100 .nu..sub.d4 = 34.97 r.sub.7 = 18.7848 d.sub.7 = (Variable)
r.sub.8 = .infin.(Stop) d.sub.8 = 0.8000 r.sub.9 = 3.4629(Aspheric)
d.sub.9 = 1.9988 n.sub.d5 = 1.80610 .nu..sub.d5 = 40.92 r.sub.10 =
9.4000 d.sub.10 = 0.5000 n.sub.d6 = 1.84666 .nu..sub.d6 = 23.78
r.sub.11 = 2.6853 d.sub.11 = 1.0000 r.sub.12 = 6.7541(Aspheric)
d.sub.12 = 1.5384 n.sub.d7 = 1.69350 .nu..sub.d7 = 53.21
r.sub.13 = -20.9589 d.sub.13 = (Variable) r.sub.14 = 92.5426
d.sub.14 = 1.7000 n.sub.d8 = 1.48749 .nu..sub.d8 = 70.23 r.sub.15 =
-17.7158 d.sub.15 = (Variable) r.sub.16 = .infin. d.sub.16 = 0.8000
n.sub.d9 = 1.51633 .nu..sub.d9 = 64.14 r.sub.17 = .infin. d.sub.17
= 1.5000 n.sub.d10 = 1.54771 .nu..sub.d10 = 62.84 r.sub.18 =
.infin. d.sub.18 = 0.8000 r.sub.19 = .infin. d.sub.19 = 0.7500
n.sub.d11 = 1.51633 .nu..sub.d11 = 64.14 r.sub.20 = .infin.
Aspherical Coefficients 9th surface K = 0 A.sub.4 = -1.2756 .times.
10.sup.-3 A.sub.6 = 8.5469 .times. 10.sup.-5 A.sub.8 = -2.1534
.times. 10.sup.-5 A.sub.10 = 0 12th surface K = 0 A.sub.4 = 9.1402
.times. 10.sup.-4 A.sub.6 = -3.4104 .times. 10.sup.-4 A.sub.8 =
7.3193 .times. 10.sup.-5 A.sub.10 = 0 Zooming Data (.infin.) WE ST
TE f (mm) 5.09894 8.67651 14.91184 F.sub.NO 2.6703 3.1805 4.5238
.omega.(.degree.) 26.1 16.1 9.5 FB (mm) 1.2024 1.2024 1.2024
d.sub.7 11.75854 4.46115 1.50000 d.sub.13 3.55591 4.48388 14.04430
d.sub.15 1.00000 3.41211 1.00000 Example 10 r.sub.1 = 7.8483
d.sub.1 = 0.7000 n.sub.d1 = 1.77250 .nu..sub.d1 = 49.60 r.sub.2 =
4.4897 d.sub.2 = 3.0000 r.sub.3 = -23.1590 d.sub.3 = 0.7000
n.sub.d2 = 1.77250 .nu..sub.d2 = 49.60 r.sub.4 = 17.2403 d.sub.4 =
0.2000 r.sub.5 = 11.6625(Aspheric) d.sub.5 = 2.4000 n.sub.d3 =
1.80610 .nu..sub.d3 = 40.92 r.sub.6 = -23.7103 d.sub.6 = 0.7000
n.sub.d4 = 1.48749 .nu..sub.d4 = 70.23 r.sub.7 = 31.9693 d.sub.7 =
(Variable) r.sub.8 = .infin.(Stop) d.sub.8 = 0.8000 r.sub.9 =
3.9499(Aspheric) d.sub.9 = 1.9988 n.sub.d5 = 1.80610 .nu..sub.d5 =
40.92 r.sub.10 = 6.9960 d.sub.10 = 0.5000 n.sub.d6 = 1.84666
.nu..sub.d6 = 23.78 r.sub.11 = 2.9591 d.sub.11 = 0.4000 r.sub.12 =
3.2957 d.sub.12 = 1.5384 n.sub.d7 = 1.69350 .nu..sub.d7 = 53.21
r.sub.13 = 6.5982(Aspheric) d.sub.13 = (Variable) r.sub.14 =
23.1151 d.sub.14 = 2.4081 n.sub.d8 = 1.48749 .nu..sub.d8 = 70.23
r.sub.15 = -12.5018 d.sub.15 = (Variable) r.sub.16 = .infin.
d.sub.16 = 0.8000 n.sub.d9 = 1.51633 .nu..sub.d9 = 64.14 r.sub.17 =
.infin. d.sub.17 = 1.5000 n.sub.d10 = 1.54771 .nu..sub.d10 = 62.84
r.sub.18 = .infin. d.sub.18 = 0.8000 r.sub.19 = .infin. d.sub.19 =
0.7500 n.sub.d11 = 1.51633 .nu..sub.d11 = 64.14 r.sub.20 = .infin.
Aspherical Coefficients 5th surface K = 0 A.sub.4 = 3.7332 .times.
10.sup.-4 A.sub.6 = -4.9736 .times. 10.sup.-6 A.sub.8 = 3.5436
.times. 10.sup.-7 A.sub.10 = 0 9th surface K = 0 A.sub.4 = -2.1597
.times. 10.sup.-4 A.sub.6 = 3.7263 .times. 10.sup.-5 A.sub.8 =
-5.1843 .times. 10.sup.-6 A.sub.10 = 0 13th surface K = 0 A.sub.4 =
4.4364 .times. 10.sup.-3 A.sub.6 = 5.7596 .times. 10.sup.-4 A.sub.8
= 1.6510 .times. 10.sup.-6 A.sub.10 = 0 Zooming Data (.infin.) WE
ST TE f (mm) 5.13995 8.70063 14.92346 F.sub.NO 2.5350 2.9786 4.5450
.omega.(.degree.) 28.8 18.0 10.7 FB (mm) 1.1864 1.1864 1.1864
d.sub.7 13.42993 3.89672 1.50000 d.sub.13 3.14297 4.00000 15.13969
d.sub.15 1.00000 3.21932 1.00000 Example 11 r.sub.1 = 55.0608
d.sub.1 = 1.4800 n.sub.d1 = 1.84666 .nu..sub.d1 = 23.78 r.sub.2 =
-210.3988 d.sub.2 = 0.1500 r.sub.3 = 58.5014 d.sub.3 = 0.7000
n.sub.d2 = 1.80610 .nu..sub.d2 = 40.92 r.sub.4 = 6.9103 d.sub.4 =
2.1504 r.sub.5 = -3.974 .times. 10.sup.-6 d.sub.5 = 0.7000 n.sub.d3
= 1.77250 .nu..sub.d3 = 49.60 r.sub.6 = 22.4439 d.sub.6 = 0.1500
r.sub.7 = 9.2836 d.sub.7 = 1.6800 n.sub.d4 = 1.84666 .nu..sub.d4 =
23.78 r.sub.8 = 17.7842 d.sub.8 = (Variable) r.sub.9 =
.infin.(Stop) d.sub.9 = 0.8000 r.sub.10 = 4.2409(Aspheric) d.sub.10
= 2.9000 n.sub.d5 = 1.80610 .nu..sub.d5 = 40.92 r.sub.11 = -1.524
.times. 10.sup.-7 d.sub.11 = 0.7000 n.sub.d6 = 1.84666 .nu..sub.d6
= 23.78 r.sub.12 = 3.1782 d.sub.12 = 0.8605 r.sub.13 =
6.0183(Aspheric) d.sub.13 = 1.6600 n.sub.d7 = 1.80610 .nu..sub.d7 =
40.92 r.sub.14 = 34.6909 d.sub.14 = (Variable) r.sub.15 = 34.2725
d.sub.15 = 1.9300 n.sub.d8 = 1.72916 .nu..sub.d8 = 54.68 r.sub.16 =
-15.9762 d.sub.16 = (Variable) r.sub.17 = .infin. d.sub.17 = 0.0100
n.sub.d9 = 1.51633 .nu..sub.d9 = = 64.14 r.sub.18 = .infin.
d.sub.18 = 1.4400 n.sub.d10 = 1.54771 .nu..sub.d10 = 62.84 r.sub.19
= .infin. d.sub.19 = 0.8000 r.sub.20 = .infin. d.sub.20 = 0.8000
n.sub.d11 = 1.51633 .nu..sub.d11 = 64.14 Aspherical Coefficients
10th surface K = 0 A.sub.4 = -4.0241 .times. 10.sup.-4 A.sub.6 =
-2.3596 .times. 10.sup.-5 A.sub.8 = -1.8718 .times. 10.sup.-6
A.sub.10 = 0 13th surface K = 0 A.sub.4 = -6.4358 .times. 10.sup.-4
A.sub.6 = 5.1034 .times. 10.sup.-5 A.sub.8 = 5.9906 .times.
10.sup.-6 A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f (mm)
5.09990 9.78208 14.70617 F.sub.NO 2.5214 3.5598 4.5000
.omega.(.degree.) 28.9 16.1 10.9 FB (mm) 1.0313 1.0313 1.0313
d.sub.8 13.84782 5.58395 1.90000 d.sub.14 1.91123 8.49778 13.77965
d.sub.16 1.89120 1.00000 1.00000 Example 12 r.sub.1 = 28.2152
d.sub.1 = 2.1000 n.sub.d1 = 1.83400 .nu..sub.d1 = 37.16 r.sub.2 =
157.3993 d.sub.2 = 0.2000 r.sub.3 = 34.3744 d.sub.3 = 0.7000
n.sub.d2 = 1.78590 .nu..sub.d2 = 44.20 r.sub.4 = 6.0000 d.sub.4 =
2.6000 r.sub.5 = .infin. d.sub.5 = 0.7000 n.sub.d3 = 1.77250
.nu..sub.d3 = 49.60 r.sub.6 = 20.7013 d.sub.6 = 0.2000 r.sub.7 =
8.1749 d.sub.7 = 1.7800 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.8 = 13.6341 d.sub.8 = (Variable) r.sub.9 = .infin.(Stop)
d.sub.9 = 0.8000 r.sub.10 = 4.3541(Aspheric) d.sub.10 = 2.7500
n.sub.d5 = 1.80610 .nu..sub.d5 = 40.92 r.sub.11 = -50.0000 d.sub.11
= 0.7000 n.sub.d6 = 1.78472 .nu..sub.d6 = 25.68 r.sub.12 = 3.2481
d.sub.12 = 0.9550 r.sub.13 = 4.5965 d.sub.13 = 1.7000 n.sub.d7 =
1.69350 .nu.d7 = 53.21 r.sub.14 = 12.3613(Aspheric) d.sub.14 =
(Variable) r.sub.15 = 30.1243 d.sub.15 = 2.1000 n.sub.d8 = 1.72916
.nu..sub.d8 = 54.68 r.sub.16 = -17.4688 d.sub.16 = (Variable)
r.sub.17 = .infin. d.sub.17 = 1.4400 n.sub.d9 = 1.54771 .nu..sub.d9
= 62.84 r.sub.18 = .infin. d.sub.18 = 0.8000 r.sub.19 = .infin.
d.sub.19 = 0.8000 n.sub.d10 = 1.51633 .nu..sub.d10 = 64.14 r.sub.20
= .infin. Aspherical Coefficients 10th surface K = 0 A.sub.4 =
-3.8980 .times. 10.sup.-4 A.sub.6 = -1.1989 .times. 10.sup.-5
A.sub.8 = -2.0218 .times. 10.sup.-6 A.sub.10 = 0 14th surface K = 0
A.sub.4 = 1.8641 .times. 10.sup.-3 A.sub.6 = 6.5713 .times.
10.sup.-5 A.sub.8 = -1.7732 .times. 10.sup.-8 A.sub.10 = 0 Zooming
Data (.infin.) WE ST TE f (mm) 5.10002 8.69938 14.69900 F.sub.NO
2.5634 3.3520 4.5553 .omega.(.degree.) 28.9 18.0 10.9 FB (mm)
0.9600 0.9600 0.9600 d.sub.8 13.85112 6.66139 2.00000 d.sub.14
1.88570 6.75477 13.41891 d.sub.16 1.78523 1.24854 1.12626 Example
13 r.sub.1 = 12.6404 d.sub.1 = 0.7000 n.sub.d1 = 1.80610
.nu..sub.d1 = 40.92 r.sub.2 = 5.3585(Aspheric) d.sub.2 = 1.8000
r.sub.3 = -1052.2383 d.sub.3 = 0.7000 n.sub.d2 = 1.83400
.nu..sub.d2 = 37.16 r.sub.4 = 10.1978 d.sub.4 = 0.8000 r.sub.5 =
9.5874 d.sub.5 = 1.8000 n.sub.d3 = 1.84666 .nu..sub.d3 = 23.78
r.sub.6 = 78.2817 d.sub.6 = (Variable) r.sub.7 = .infin.(Stop)
d.sub.7 = 1.2000 r.sub.8 = 4.6302 d.sub.8 = 2.5000 n.sub.d4 =
1.80610 .nu..sub.d4 = 40.92 r.sub.9 = 45.0000 d.sub.9 = 0.7000
n.sub.d5 = 1.84666 .nu..sub.d5 = 23.78 r.sub.10 = 4.6040 d.sub.10 =
0.5000 r.sub.11 = 9.9218(Aspheric) d.sub.11 = 2.0000 n.sub.d6 =
1.69350 .nu..sub.d6 = 53.21 r.sub.12 = -10.0000 d.sub.12 = 0.7000
n.sub.d7 = 1.83400 .nu..sub.d7 = 37.16 r.sub.13 = -165.7669
d.sub.13 = (Variable) r.sub.14 = 9.9392 d.sub.14 = 1.8000 n.sub.d8
= 1.60311 .nu..sub.d8 = 60.64 r.sub.15 = -128.8622 d.sub.15 =
(Variable) r.sub.16 = .infin. d.sub.16 = 0.8000 n.sub.d9 = 1.51633
.nu..sub.d9 = 64.14 r.sub.17 = .infin. d.sub.17 = 1.5000 n.sub.d10
= 1.54771 .nu..sub.d10 = 62.84 r.sub.18 = .infin. d.sub.18 = 0.8000
r.sub.19 = .infin. d.sub.19 = 0.7500 n.sub.d11 = 1.51633
.nu..sub.d11 = 64.14 r.sub.20 = .infin. Aspherical Coefficients 2nd
surface K = 0 A.sub.4 = -3.6379 .times. 10.sup.-4 A.sub.6 = 1.7551
.times. 10.sup.-5 A.sub.8 = -1.2517 .times. 10.sup.-6 A.sub.10 = 0
11th surface K = 0 A.sub.4 = -2.3148 .times. 10.sup.-3 A.sub.6 =
-1.0121 .times. 10.sup.-4 A.sub.8 = -1.9212 .times. 10.sup.-5
A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f (mm) 4.49468 8.69002
12.90381 F.sub.NO 2.6082 3.4008 4.4891 FB (mm) 1.2101 1.2101 1.2101
d.sub.6 14.27434 3.90534 1.50000 d.sub.13 2.53628 7.27318 14.59773
d.sub.15 0.92173 1.80916 1.00286 Example 14 r.sub.1 = 12.0734
d.sub.1 = 0.7000 n.sub.d1 = 1.78590 .nu..sub.d1 = 44.20 r.sub.2 =
5.1454(Aspheric) d.sub.2 = 1.8000 r.sub.3 = 32.6348 d.sub.3 =
0.7000 n.sub.d2 = 1.78590 .nu..sub.d2 = 44.20 r.sub.4 = 7.1978
d.sub.4 = 0.8000 r.sub.5 = 7.2194 d.sub.5 = 1.8000 n.sub.d3 =
1.84666 .nu..sub.d3 = 23.78 r.sub.6 = 17.2322 d.sub.6 = (Variable)
r.sub.7 = .infin.(Stop) d.sub.7 = 1.2000 r.sub.8 = 5.5218 d.sub.8 =
3.0000 n.sub.d4 = 1.77250 .nu..sub.d4 = 49.60 r.sub.9 = -14.5871
d.sub.9 = 0.2000 r.sub.10 = -10.6445 d.sub.10 = 0.7000 n.sub.d5 =
1.84666 .nu..sub.d5 = 23.78 r.sub.11 = 16.3389 d.sub.11 = 0.7000
r.sub.12 = 18.1849 d.sub.12 = 1.6000 n.sub.d6 = 1.69350 .nu..sub.d6
= 53.21 r.sub.13 = 36.1930(Aspheric) d.sub.13 (Variable) r.sub.14 =
14.4210 d.sub.14 = 1.8000 n.sub.d7 = 1.60311 .nu..sub.d7 = 60.64
r.sub.15 = -33.5831 d.sub.15 = (Variable) r.sub.16 = .infin.
d.sub.16 = 0.8000 n.sub.d8 = 1.51633 .nu..sub.d8 = 64.14 r.sub.17 =
.infin. d.sub.17 = 1.5000 n.sub.d9 = 1.54771 .nu..sub.d9 = 62.84
r.sub.18 = .infin. d.sub.18 = 0.8000 r.sub.19 = .infin. d.sub.19 =
0.7500 n.sub.d10 = 1.51633 .nu..sub.d10 = 64.14 r.sub.20 = .infin.
Aspherical Coefficients 2nd surface K = 0 A.sub.4 = -4.0112 .times.
10.sup.-4 A.sub.6 = 2.0947 .times. 10.sup.-6 A.sub.8 = -1.4672
.times. 10.sup.-6 A.sub.10 = 0 13th surface K = 0 A.sub.4 = 2.2371
.times. 10.sup.-3 A.sub.6 = 5.3785 .times. 10.sup.-6 A.sub.8 =
8.2914 .times. 10.sup.-6 A.sub.10 = 0 Zooming Data (.infin.) WE ST
TE f (mm) 4.50022 8.68802 12.89916 F.sub.NO 2.5959 3.4326 4.5355
.omega.(.degree.) 29.1 16.1 11.0 FB (mm) 1.2095 1.2095 1.2095
d.sub.6 11.49994 3.44847 1.50000 d.sub.13 2.53628 7.27553 14.45109
d.sub.15 0.92173 1.87176 0.98646 Example 15 r.sub.1 = 35.3386
d.sub.1 = 0.7000 n.sub.d1 = 1.80610 .nu..sub.d1 = 40.92 r.sub.2 =
7.9569(Aspheric) d.sub.2 = 0.5000 r.sub.3 = 12.9234 d.sub.3 =
0.7000 n.sub.d2 = 1.806102 .nu..sub.d2 = 40.92 r.sub.4 = 5.6199
d.sub.4 = 1.3000 r.sub.5 = 7.6443 d.sub.5 = 1.8000 n.sub.d3 =
1.84666 .nu..sub.d3 = 23.78 r.sub.6 = 20.9906 d.sub.6 = (Variable)
r.sub.7 = .infin.(Stop) d.sub.7 = 1.2000 r.sub.8 = 6.1200(Aspheric)
d.sub.8 = 2.5000 n.sub.d4 = 1.80610 .nu..sub.d4 = 40.92 r.sub.9 =
-12.0000 d.sub.9 = 0.7000 n.sub.d5 = 1.80518 .nu..sub.d5 = 25.42
r.sub.10 = 10.6145 d.sub.10 = 0.5000 r.sub.11 = 12.5527 d.sub.11 =
0.7000 n.sub.d6 = 1.80100 .nu..sub.d6 = 34.97 r.sub.12 = 5.4000
d.sub.12 = 2.0000 n.sub.d7 = 1.69350 .nu..sub.d7 = 53.21 r.sub.13 =
26.5712(Aspheric) d.sub.13 = (Variable) r.sub.14 = 13.7480 d.sub.14
= 1.8000 n.sub.d8 = 1.60311 .nu..sub.d8 = 60.64 r.sub.15 = -31.8437
d.sub.15 = (Variable) r.sub.16 = .infin. d.sub.16 = 0.8000 n.sub.d9
= 1.51633 .nu..sub.d9 = 64.14 r.sub.17 = .infin. d.sub.17 = 1.5000
n.sub.d10 = 1.54771 .nu..sub.d10 = 62.84 r.sub.18 = .infin.
d.sub.18 = 0.8000 r.sub.19 = .infin. d.sub.19 = 0.7500 n.sub.d11 =
1.51633 .nu..sub.d11 = 64.14 r.sub.20 = .infin. Aspherical
Coefficients 2nd surface K = 0 A.sub.4 = -3.6019 .times. 10.sup.-4
A.sub.6 = -2.9205 .times. 10.sup.-6 A.sub.8 = -1.7745 .times.
10.sup.-7 A.sub.10 = 0 8th surface K = 0 A.sub.4 = -6.7970 .times.
10.sup.-5 A.sub.6 = 3.2948 .times. 10.sup.-6 A.sub.8 = -8.4365
.times. 10.sup.-7 A.sub.10 = 0 13th surface K = 0 A.sub.4 = 1.6571
.times. 10.sup.-3 A.sub.6 = 5.7013 .times. 10.sup.-5 A.sub.8 =
1.8429 .times. 10.sup.-6 A.sub.10 = 0 Zooming Data (.infin.) WE ST
TE f (mm) 4.50018 8.68952 12.89980 F.sub.NO 2.6082 3.4008 4.4891
.omega.(.degree.) 29.1 16.1 11.0 FB (mm) 1.2099 1.2099 1.2099
d.sub.6 15.08390 4.40851 1.50000 d.sub.13 2.53628 6.90868 13.07068
d.sub.15 0.92173 1.55996 0.99972 Example 16 r.sub.1 = 10.6805
d.sub.1 = 0.7000 n.sub.d1 = 1.80610 .nu..sub.d1 = 40.92 r.sub.2 =
5.3858(Aspheric) d.sub.2 = 2.0000 r.sub.3 = 53.1437 d.sub.3 =
0.7000 n.sub.d2 = 1.77250 .nu..sub.d2 = 49.60 r.sub.4 = 9.7714
d.sub.4 = 0.6000 r.sub.5 = 7.5402 d.sub.5 = 1.8000 n.sub.d3 =
1.84666 .nu..sub.d3 = 23.78 r.sub.6 = 14.1942 d.sub.6 = (Variable)
r.sub.7 = .infin.(Stop) d.sub.7 = 1.2000 r.sub.8 = 4.9282(Aspheric)
d.sub.8 = 2.5000 n.sub.d4 = 1.80610 .nu..sub.d4 = 40.92 r.sub.9 =
-97.2877 d.sub.9 = 0.2000 r.sub.10 = -10.3515 d.sub.10 = 0.7000
n.sub.d5 = 1.84666 .nu..sub.d5 = 23.78 r.sub.11 = 9.5288 d.sub.11 =
2.0000 n.sub.d6 = 1.69350 .nu..sub.d6 = 53.21 r.sub.12 =
486.8769(Aspheric) d.sub.12 = (Variable) r.sub.13 = 19.3730
d.sub.13 = 1.8000 n.sub.d7 = 1.60311 .nu..sub.d7 = 60.64 r.sub.14 =
-15.6402 d.sub.14 = (Variable) r.sub.15 = .infin. d.sub.15 = 0.8000
n.sub.d8 = 1.51633 .nu..sub.d8 = 64.14 r.sub.16 = .infin. d.sub.16
= 1.5000 n.sub.d9 = 1.54771 .nu..sub.d9 = 62.84 r.sub.17 = .infin.
d.sub.17 = 0.8000 r.sub.18 = .infin. d.sub.18 = 0.7500 n.sub.d10 =
1.51633 .nu..sub.d10 = 64.14 Aspherical Coefficients 2nd surface K
= 0 A.sub.4 = -2.6043 .times. 10.sup.-4 A.sub.6 = 1.7480 .times.
10.sup.-5 A.sub.8 = -8.2296 .times. 10.sup.-7 A.sub.10 = 0 8th
surface K = 0 A.sub.4 = 4.6735 .times. 10.sup.-4 A.sub.6 = 5.7258
.times. 10.sup.-6 A.sub.8 = 3.2901 .times. 10.sup.-6 A.sub.10 = 0
12th surface K = 0 A.sub.4 = 3.7339 .times. 10.sup.-3 A.sub.6 =
-3.6398 .times. 10.sup.-5 A.sub.8 = 4.5323 .times. 10.sup.-5
A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f (mm) 4.50325 8.68909
12.89876 F.sub.NO 2.4094 3.2779 4.3298 .omega.(.degree.) 29.0 16.1
11.0 FB (mm) 1.2089 1.2089 1.2089 d.sub.6 13.28426 3.96560 1.50000
d.sub.12 2.53628 7.09770 13.37693 d.sub.14 0.92173 1.54147 0.98679
Example 17 r.sub.1 = 88.1913 d.sub.1 = 0.7000 n.sub.d1 = 1.77250
.nu..sub.d1 = 49.60 r.sub.2 = 4.6149(Aspheric) d.sub.2 = 2.0000
r.sub.3 = 8.1050 d.sub.3 = 1.8000 n.sub.d2 = 1.84666 .nu..sub.d2 =
23.78 r.sub.4 = 16.5728 d.sub.4 = (Variable) r.sub.5 =
.infin.(Stop) d.sub.6 = 1.2000 r.sub.6 = 5.7305(Aspheric) d.sub.6 =
2.5000 n.sub.d3 = 1.80610 .nu..sub.d3 = 40.92 r.sub.7 = -12.0000
d.sub.7 = 0.7000 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78 r.sub.8 =
12.1053 d.sub.8 = 0.5000 r.sub.9 = 11.4889 d.sub.9 = 0.7000
n.sub.d6 = 1.80100 .nu..sub.d5 = 34.97 r.sub.10 = 5.4000 d.sub.10 =
2.0000 n.sub.d6 = 1.69350 .nu..sub.d6 = 53.21 r.sub.11 =
16.7663(Aspheric) d.sub.11 = (Variable) r.sub.12 = 38.7731 d.sub.12
= 1.8000 n.sub.d7 = 1.65844 .nu..sub.d7 = 50.88 r.sub.13 = -15.0285
d.sub.13 = (Variable) r.sub.14 = .infin. d.sub.14 = 0.8000 n.sub.d8
= 1.51633 .nu..sub.d8 = 64.14 r.sub.15 = .infin. d.sub.15 = 1.5000
n.sub.d9 = 1.54771 .nu..sub.d9 = 62.84 r.sub.16 = .infin. d.sub.16
= 0.8000 r.sub.17 = .infin. d.sub.17 = 0.7500 n.sub.d10 = 1..51633
.nu..sub.d10 = 64.14 r.sub.18 = .infin. Aspherical Coefficients 2nd
surface K = 0 A.sub.4 = -1.0782 .times. 10.sup.-3 A.sub.6 = 2.8661
.times. 10.sup.-5 A.sub.8 = -4.2769 .times. 10.sup.-6 A.sub.10 = 0
6th surface K = 0 A.sub.4 = -2.4989 .times. 10.sup.-5 A.sub.6 =
-1.3301 .times. 10.sup.-5 A.sub.8 = 4.1349 .times. 10.sup.-7
A.sub.10 = 0 11th surface K = 0 A.sub.4 = 2.7617 .times. 10.sup.-3
A.sub.6 = -4.5942 .times.
10.sup.-5 A.sub.8 = 2.1334 .times. 10.sup.-5 A.sub.10 = 0 Zooming
Data (.infin.) WE ST TE f (mm) 4.51347 8.68762 12.89665 F.sub.NO
2.6082 3.4008 4.4891 .omega.(.degree.) 29.0 16.1 11.0 FB (mm)
1.2096 1.2096 1.2096 d.sub.6 12.59150 3.96970 1.50000 d.sub.12
2.53628 7.22258 13.31431 d.sub.14 0.92173 1.50740 0.99736
[0174] FIGS. 18(a) to 18(c) are aberration diagram for Example 1
upon focused at infinity. FIG. 18(a) shows spherical aberration SA,
astigmatism AS, distortion DT and chromatic aberration CC of
magnification at the wide-angle end, FIG. 18(b) shows SA, AS, DT
and CC in the intermediate settings, and FIG. 18(c) shows SA, AS,
DT and CC at the telephoto end. Note that "FLY" shows an image
height.
[0175] Enumerated below are the values of conditions (1) to (13),
(a) and (b) in the aforesaid examples.
2 Condition Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 (1) 0.0730 0.0842 0.0855
0.0895 0.0938 (2) 0.7239 0.7545 0.5554 0.5912 0.4022 (3) 0 0 0 0 0
(4) -1.6487 -2.3115 -1.5012 -1.3066 -2.0910 (5) 0.3150 0.2131
0.5205 0.2065 0.1952 (6) -0.8779 -0.9081 -0.9907 -0.9998 -0.8315
(7) -0.0150 -0.0363 -0.0003 -0.0001 (8) 0.5142 0.3367 0.3811 0.3486
*** (9) *** *** *** *** *** (10) *** *** *** *** 0.0000 (11) 0.8804
0.8357 1.0053 0.9556 1.1085 (L = .64) (L = 5.64) (L = 5.64) (L =
5.64) (L = 5.64) (12) 1.2152 1.0534 1.0372 1.0099 0.9456 (L = 5.64)
(L = 5.64) (L = 5.64) (L = 5.64) (L = 5.64) (13) .times. 10.sup.-3
0.333 0.333 0.333 0.333 0.333 (a in .mu.m) (a = 3.0) (a = 3.0) (a =
3.0) (a = 3.0) (a = 3.0) (a) 1.6439 1.6756 1.5643 1.5400 1.6672 (b)
2.2668 2.2257 2.2667 2.3526 2.1924 Condition Ex. 6 Ex. 7 Ex. 8 Ex.
9 Ex. 10 (1) 0.0912 0.1207 0.1102 0.0993 0.1127 (2) 0.3820 0.6149
0.5182 0.7845 1.0917 (3) 0 0 0 0 0 (4) -0.6830 -0.9323 -0.4689
-0.5126 -2.9959 (5) 0.1746 -0.2734 --0.4434 0.6786 0.3510 (6)
-0.8322 -1 -1.0241 -1.2037 -1.4572 (7) *** *** 0.2151 *** *** (8)
*** *** 0.7777 *** *** (9) *** 0.9821 *** 0.7989 *** (10) 0.01044
*** *** *** *** (11) 1.1203 1.7321 1.0000 1.6600 1.3652 (L = 5.64)
(L = 5.6) (L = 5.0) (L = 5.0) (L = 5.64) (12) 0.9726 1.0357 0.9074
1.0074 0.7867 (L = 5.64) (L = 5.6) (L = 5.0) (L = 5.0) (L = 5.64)
(13) .times. 10.sup.-3 0.333 0.333 0.333 0.333 0.333 (a in .mu.m)
(a = 3.0) (a = 3.0) (a = 3.0) (a = 3.0) (a = 3.0) (a) 1.6257 1.6976
1.7299 1.7290 1.7056 (b) 2.2145 2.1761 2.4925 1.8077 2.0835
Condition Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 (1) 0.1144 0.1147
0.1094 0.1452 0.1094 (2) 0.5975 0.5250 0.3833 0.1091 0.1088 (3) 0 0
0 0 0 (4) -1.4198 -2.1839 -0.8871 -3.0196 -2.7909 (5) 0.3641 0.2659
-0.8568 -0.3992 0.3969 (6) 1 0.9565 -1.0012 *** -5.2936 (7) *** ***
0.3556 0.3727 0.1273 (8) *** *** 0.1780 0.1778 0.2889 (9) 1.2252
1.0638 *** *** *** (10) *** *** *** *** *** (11) 1.2430 1.4681
1.1600 1.1600 1.000 (L = 5.64) (L = 5.64) (L = 5.0) (L = 5.0) (L =
5.0) (12) 1.0852 1.0824 1.2800 1.2400 1.2800 (L = 5.64) (L = 5.64)
(L = 5.0) (L = 5.0) (L = 5.0) (13) .times. 10.sup.-3 0.333 0.333
0.333 0.333 0.333 (a in .mu.m) (a = 3.0) (a = 3.0) (a = 3.0) (a =
3.0) (a = 3.0) (a) 1.4670 1.5144 1.6684 1.8643 1.50981 (b) 2.1071
2.0657 2.5012 2.2008 2.4139 Condition Ex. 16 Ex. 17 (1) 0.1666
0.1904 (2) 0.4205 0.0645 (3) 0 0 (4) -1.0399 -5.3540 (5) 0.1066
0.4413 (6) -21.8621 -80.9524 (7) 0.4216 0.0512 (8) 0.1332 0.4431
(9) *** *** (10) *** *** (11) 1.1600 0.7000 (L = 5.0) (L = 5.0)
(12) 1.0800 1.2800 (13) .times. 10.sup.-3 0.333 0.333 (a in .mu.m)
(a = 3.0) (a = 3.0) (a) 1.6411 1.9843 (b) 2.2790 2.2059
[0176] The near-infrared cut filter FI is now explained in detail.
This filter FI comprises a plane-parallel plate provided on its
entrance surface side with a near-infrared cut coating for limiting
chiefly the transmission of light in a longer wavelength range and
on its exit surface side with a shorter wavelength cut coating for
limiting chiefly the transmission of light in a shorter wavelength
range. This near-infrared cut coating is designed in such a way as
to have a transmittance of 80% or greater at 600 nm wavelength and
a transmittance of 10% or less at 700 nm wavelength. To be more
specific, a 27-layered IR cut coating film having such
transmittance characteristics as shown in FIG. 19 is used. Set out
below are data about such a multilayered coating film. This filter
comprises such a plane-parallel plate substrate as mentioned above,
on which 27 layers of Al.sub.2O.sub.3, TiO.sub.2 and SiO.sub.2 are
laminated in the following order. Design wavelength .lambda. is 780
nm.
3 Substrate Physical Layer No. Material Thickness, nm .lambda./4 1
Al.sub.2O.sub.3 58.96 0.50 2 TiO.sub.2 84.19 1.00 3 SiO.sub.2
134.14 1.00 4 TiO.sub.2 84.19 1.00 5 SiO.sub.2 134.14 1.00 6
TiO.sub.2 84.19 1.00 7 SiO.sub.2 134.14 1.00 8 TiO.sub.2 84.19 1.00
9 SiO.sub.2 134.14 1.00 10 TiO.sub.2 84.19 1.00 11 SiO.sub.2 134.14
1.00 12 TiO.sub.2 84.19 1.00 13 SiO.sub.2 134.14 1.00 14 TiO.sub.2
84.19 1.00 15 SiO.sub.2 178.41 1.33 16 TiO.sub.2 101.03 1.21 17
SiO.sub.2 167.67 1.25 18 TiO.sub.2 96.82 1.15 19 SiO.sub.2 147.55
1.05 20 TiO.sub.2 84.19 1.00 21 SiO.sub.2 160.97 1.20 22 TiO.sub.2
84.19 1.00 23 SiO.sub.2 154.26 1.15 24 TiO.sub.2 95.13 1.13 25
SiO.sub.2 160.97 1.20 26 TiO.sub.2 99.34 1.18 27 SiO.sub.2 87.19
0.65 Air
[0177] The shorter wavelength cut coating film on the exit surface
side of the low-pass filter has such transmittance characteristics
as shown in FIG. 20, and is again formed by multi-coating, so that
the color reproducibility of an electronic image can be much more
enhanced.
[0178] With this shorter wavelength cut coating film, for instance,
it is possible to control the ratio of the 420 nm wavelength
transmittance with respect to the transmittance of a wavelength
having the highest transmittance in the wavelength range of 400 nm
to 700 nm to 15% or greater and the ratio of the 400 nm wavelength
transmittance with respect to the transmittance of the wavelength
having the highest transmittance to 6% or less.
[0179] It is thus possible to reduce a discernible difference
between the colors perceived by the human eyes and the colors of an
image upon phototaken and reproduced. To put it another way, it is
possible to prevent any image deterioration due to the fact that
shorter wavelength side colors less likely to be perceived by the
human sense of sight can be easily perceived by the human eyes.
[0180] When the aforesaid ratio of the 400 nm wavelength
transmittance exceeds 6%, the shorter wavelength range less likely
to be perceived by the human eyes is reproduced in colors capable
of perception. When the aforesaid ratio of the 420 nm wavelength
transmittance is less than 15%, on the contrary, the
reproducibility of colors in the wavelength range capable of being
perceived by the human eyes drops, resulting in the reproduction of
ill-balanced colors.
[0181] The means for limiting such wavelengths can more
advantageously be used with an image pickup system using a
complementary color mosaic filter.
[0182] Used in each of the foregoing examples is a coating having a
transmittance of 0% at 400 nm wavelength and a transmittance of 90%
at 420 nm wavelength, with a transmittance peak of 100% obtained at
440 nm wavelength, as shown in FIG. 20.
[0183] With the synergistic effect of this coating and the
aforesaid near-infrared cut coating, it is thus possible to achieve
a color control filter having a transmittance of 0% at 400 nm, a
transmittance of 80% at 420 nm, a transmittance of 82% of at 600 nm
and a transmittance of 2% at 700 nm, with a transmittance peak of
99% obtained at 450 nm. With this color control filter, faithful
color reproduction is achievable.
[0184] The low-pass filter FL comprises three types of filter
elements put one upon another in the optical axis direction, each
of which elements has crystallographic axes in the azimuth
directions of horizontal (=0.degree.) and .+-.45.degree. upon
projection on an image plane. For moire reductioins, the elements
are each shifted by a.mu.m in the horizontal direction and
SQRT(1/2).times.a in the .+-.45.degree. direction. Here SQRT means
a square root.
[0185] The image pickup plane I of the CCD is provided thereon with
a complementary color mosaic filter in a mosaic manner where four
color filter elements, viz., cyan, magenta, yellow and green filter
elements are in alignment with image pickup pixels. Substantially
the same number of filter elements are located for each of these
four types of color filters in such a mosaic way that adjacent
pixels do not correspond to the same type of color filter elements,
thereby achieving more faithful color reproduction.
[0186] To be more specific, the complementary color filter is made
up of at least four types of color filter elements, as shown in
FIG. 21. Preferably in this case, the four types of color filters
should be such characteristics as mentioned just below.
[0187] A green color filter G has a spectral strength peak at a
wavelength G.sub.p,
[0188] a yellow color filter Y.sub.e has a spectral strength peak
at a wavelength Y.sub.p,
[0189] a cyan color filter C has a spectral strength peak at a
wavelength C.sub.p, and
[0190] a magenta color filter M has peaks at wavelengths M.sub.p1
and M.sub.p2, provided that
510 nm<G.sub.p<540 nm
5 nm<Y.sub.p-G.sub.p<35 nm
-100 nm<C.sub.p-G.sub.p<-5 nm
430 nm<M.sub.p1<480 nm
580 nm<M.sub.p2<640 nm
[0191] In addition, it is preferable that each of the green, yellow
and cyan color filters has a strength of 80% or greater at 530 nm
wavelength with respect to its spectral strength peak, and the
magenta color filter has a strength of 10% to 50% inclusive at 530
nm wavelength with respect to its spectral strength peak.
[0192] One example of the wavelength characteristics of each color
filter in this embodiment is shown in FIG. 22. The green color
filter G has a spectral strength peak at 525 nm. The yellow color
filter Y.sub.e has a spectral strength peak at 555 nm. The cyan
color filter has a spectral strength peak at 510 nm. The magenta
color filter has spectral strength peaks at 445 nm and 620 nm. The
color filter at 530 nm has a strength of 99% for G, 95% for
Y.sub.e, 97% for C, and 38% for M with respect to its spectral
strength peak.
[0193] When such a complementary color filter is used as the
filter, the filtered light is converted by a controller (not shown
or used with a digital camera) to R (red), G (green) and B (blue)
signals according to the following electrical signal
processing:
[0194] for luminance signals
Y=.vertline.G+M+Y.sub.e+C.vertline..times.1/4
[0195] for color signals
R-Y=.vertline.(M+Y.sub.e)-(G+C).vertline.
B-Y=.vertline.(M+C)-(G+Y.sub.e).vertline.
[0196] Light in a longer or shorter wavelength range is less likely
to be perceived by the human eyes. As this light reaches a CCD,
however, color reproducibility becomes worse due to unsatisfactory
signal processing, because the CCD has high light sensitivity. With
this embodiment of the present invention, it is possible to achieve
satisfactory color reproduction by use of an IR cut filter and a
shorter wavelength cut filter.
[0197] This IR cut filter may be located everywhere on the optical
path. In the case of electronic image pickup equipment, however,
the IR filter should preferably be located between the lens group
nearest to the image side of the equipment and an image plane (a
CCD or the like), because the filter can be made compact and the
effect of the filter can be made uniform. The number of the
low-pass filter FL may be one or two as already mentioned.
[0198] FIG. 23 is a schematic of part of one embodiment of the
electronic image pickup equipment according to the present
invention. In this embodiment, a turret 29 is disposed on an
optical axis 15 between the first lens group G1 and the second lens
group G2 of the image pickup system (zoom lens system) so as to
control brightness to 0, -1, -2 and -3 levels. Otherwise, the
construction of the image pickup optical system or the like is the
same as that of each of the aforesaid embodiments.
[0199] The turret 129 has aperture stops provided with a
plane-parallel plate 130, a -1 level ND filter 131, -2 level ND
filter 132 and -3 level ND filter 133, which are successively
positioned on an optical path defined by the optical axis 5 in
unison with the rotation of the turret 129, thereby controlling the
quantity of light incident on an image pickup device 2 having a
complementary color filter. The plane-parallel plate 130 and ND
filters 31, 32 and 33 are each provided on its surface with a
coating film 28 having a wavelength correction function of allowing
its transmittance to become a half-value of its e-line
transmittance between g-line and h-line, thereby reducing color
flares due to chromatic aberrations occurring on the shorter
wavelength side. In addition, these apertures are designed in such
a way as to satisfy the requirements recited in claims 23, 24 and
25.
[0200] In association with each ND filter (31 to 33), the overall
transmittance drops to 1/2, 1/4 and 1/8, respectively.
[0201] Another embodiment of the aperture stops is shown in FIG.
24. A turret 10 capable of controlling brightness to 0, -1, -2, -3
and -4 levels is provided at a stop position on an optical axis
between the first lens group G1 and the second lens group G2 of an
image pickup optical system. The turret 10 is provided with a
circular aperture 1A for 0 level control, which aperture has a
diameter of about 4.5 mm and comprises a fixed space (and has a
transmittance of 100% with respect to 550 nm wavelength), an
aperture 1B for -1 level correction, which aperture comprises a
transparent plane-parallel plate (having a transmittance of 99%
with respect to 550 nm wavelength) having an aperture area that is
about a half the aperture area of the aperture 1A and a fixed
aperture shape, and apertures 1C, 1D and 1E having ND filters for
-2, -3 and -4 level corrections, which filters have a transmittance
of 50%, 25% and 13%, respectively, with respect to 550 nm
wavelength.
[0202] For light quantity control, any one of the apertures is
aligned with the stop position by the rotation of the turret 10
around an rotating shaft 11.
[0203] When an effective F-number F.sub.no' is F.sub.no'>a/0.4
.mu.m, an ND filter having a transmittance of less than 80% with
respect to 550 nm wavelength is inserted into the aperture.
Referring here to Example 1 for instance, the effective F-number at
the telephoto end conforms to this condition when the effective
F-number at the -2 level comes to 9.0 with respect to that at the 0
level (the stop opens). The then aperture is 1C. It is thus
possible to reduce an image deterioration caused by a diffraction
phenomenon due to stop-down.
[0204] Instead of the turret 10 shown in FIG. 24, such a turret 10'
as shown in FIG. 25(a) may be used. The turret 10' capable of
controlling brightness to 0, -1, -2, -3 and -4 levels is provided
at an aperture stop position on an optical axis between the first
lens group G1 and the second lens group G2 of an image pickup
optical system. The turret 10' is provided with a circular, fixed
aperture 1A' for 0 level control, which aperture has a diameter of
about 4.5 mm and a fixed aperture shape, an aperture 1B' for -1
level correction, which aperture has an aperture area that is about
a half the aperture area of the aperture 1A and a fixed aperture
shape, and apertures 1C', 1D' and 1E' for -2, -3 and -4 level
corrections, the aperture areas of which decrease by 50% in this
order and each of which has a fixed aperture shape. For light
quantity control, any one of the apertures is aligned with the stop
position by the rotation of the turret 10' around a rotating shaft
11.
[0205] In addition, optical low-pass filters with varying spatial
frequency characteristics are used for 1A' to 1D' out of these
apertures. As shown in FIG. 25(b), the optical filters are designed
in such a way that the smaller the aperture diameter, the higher
the spatial frequency characteristics are. It is thus possible to
reduce an image deterioration caused by a diffraction phenomenon
due to stop-down. It is here noted that the curves of FIG. 25(b)
show the spatial frequency characteristics of only the low-pass
filters. In other words, the filters are designed in such a way
that the characteristics inclusive of diffraction characteristics
due to each stop are all on the same level. It is thus possible to
achieve electronic image pickup equipment enabling a constant
low-pass effect to be always ensured irrespective of the f
number.
[0206] The aforesaid electronic image pickup equipment according to
the present invention may be used for phototaking systems wherein
an object image formed by the zoom lens system is sensed by an
image pickup device such as a CCD or silver salt film, especially
digital cameras or video cameras, personal computers that are one
example of information processors, and telephones, especially
convenient-to-carry portable telephones, as embodied just
below.
[0207] FIGS. 26 to 28 are conceptual schematics of a digital camera
where the zoom lens system according to the present invention is
incorporated in a phototaking optical system 41 thereof. FIG. 26 is
a front perspective view illustrative of the outside shape of a
digital camera 40, and FIG. 27 is a rear perspective view
illustrative of the digital camera 40. FIG. 28 is a sectional view
illustrative of the construction of the digital camera 40. The
digital camera 40 according to the instant embodiment comprises a
phototaking optical system 41 including a phototaking optical path
42, a finder optical system 43 including a finder optical path 44,
a shutter button 45, a flash 46 and a liquid crystal display
monitor 47. Upon pressing down the shutter button 45 located on the
upper portion of the camera 40, phototaking occurs through the
phototaking optical system 41, for instance, the zoom lens system
set forth in Example 1. An object image formed through the
phototaking optical system 11 is then formed on the image pickup
plane of a CCD 49 via filters F1, F2 such as an optical low-pass
filter and a near-infrared cut filter. The object image sensed by
this CCD 49 is displayed as an electronic image on the liquid
crystal display monitor 47 located on the back side of the camera
via processing means 51. This processing means 51 may be connected
with recording means 52 for recording the phototaken electronic
image. It is here noted that the recording means 52 may be provided
separately from the processing means 51 or in the form of
electronic read/write means comprising a floppy disk, a memory card
or an MO. Instead of CCD 49, a silver salt camera with silver salt
film loaded therein may be used.
[0208] Further, a finder objective optical system 53 is located on
the finder optical path 444. An object image formed by this finder
objective optical system 53 is then formed on a field frame 57 of a
Porro prism 55 that is an image erecting member. In the rear of the
Porro prism 55, there is provided an eyepiece optical system 59 for
guiding an erected image to an observer's eyeball E. It is here
noted that a cover member 50 is provided on the entrance side of
phototaking optical system 41 and finder optical system 53 while a
cover member 50 is disposed on the exit side of eyepiece optical
system 59.
[0209] The thus constructed digital camera 40 can have ever-higher
performance at ever-lower costs, because the phototaking optical
system 41 used therewith is a compact zoom lens system having an
ever-wider angle and an ever-higher zoom ratio with well-corrected
aberrations.
[0210] While plane-parallel plates are used for the cover members
50 in the embodiment of FIG. 28, it is understood that lenses
having powers may be used.
[0211] Shown in FIGS. 29 to 31 is a personal computer that is one
example of the information processor in which the zoom lens system
of the invention is incorporated in the form of an objective
optical system. FIG. 29 is a front perspective views of an
uncovered personal computer 300, FIG. 30 is a sectional view of a
phototaking optical system 303 mounted on the personal computer
300, and FIG. 31 is a side view of FIG. 29. As depicted in FIGS. 29
to 31, the personal computer 300 comprises a key board 301 for
allowing an operator to enter information therein from outside,
information processing and recording means (not shown), a monitor
302 for displaying the information to the operator and a
phototaking optical system 303 for phototaking an image of the
operator per se and images of operator's surroundings. The monitor
302 used herein may be a transmission type liquid crystal display
device designed to be illuminated by a backlight (not shown) from
the back side, a reflection type liquid crystal display device
designed to display images by reflecting light from the front side,
a CRT display or the like. As shown, the phototaking optical system
303 is built in a right upper portion of monitor 302. However, it
is to be understood that the phototaking optical system 303 may be
positioned somewhere on the periphery of monitor 302 or keyboard
301.
[0212] The phototaking optical system 303 includes on a phototaking
optical path 304 an objective lens system 112 comprising the zoom
lens system of the invention (roughly illustrated) and an image
pickup element chip 162 for receiving an image. These are built in
the personal computer 300.
[0213] It is here to be understood that an optical low-pass filter
F is additionally pasted onto the image pickup element chip 162 to
construct an integral image pickup unit 160. This image pickup unit
160 can be fitted in the rear end of a lens barrel 113 of the
objective lens system 112 in one-touch simple operation, so that
centering and alignment of the objective lens system 112 with
respect to the image pickup element chip 162 can be dispensed with
to make assembly simple. At the end of the lens barrel 113, there
is provided a cover glass 114 for protection of the objective lens
system 112. It is here to be understood that the zoom lens driving
mechanism in the lens barrel 113 is not shown.
[0214] An object image received at the image pickup element chip
162 is entered from a terminal 166 in the processing means in the
personal computer 300, and displayed as an electronic image on the
monitor 302. Shown in FIG. 29 as an example is a phototaken image
305 of the operator. It is possible to display the image 305, etc.
on a personal computer at the other end on a remote place via an
internet or telephone line.
[0215] Illustrated in FIG. 32 is a telephone handset that is one
example of the information processor in which the zoom lens system
of the invention is built in the form of a phototaking optical
system, especially a convenient-to-carry portable telephone
handset. FIG. 32(a) is a front view of a portable telephone handset
400, FIG. 32(b) is a side view of handset 400 and FIG. 32(c) is a
sectional view of a phototaking optical system 405. As depicted in
FIGS. 32(a) to 21(c), the telephone handset 400 comprises a
microphone portion 401 for entering an operator's voice therein as
information, a speaker portion 402 for producing a voice of a
person on the other end, an input dial 403 allowing the operator to
enter information therein, a monitor 404 for displaying phototaken
images of the operator and the person on the other end and
information such as telephone numbers, a phototaking optical system
405, an antenna 406 for transmitting and receiving communication
waves and a processing means (not shown) for processing image
information, communication information, input signals, etc. The
monitor 404 used herein is a liquid crystal display device. The
arrangement of these parts is not necessarily limited to that
illustrated. The phototaking optical system 405 includes on a
phototaking optical path 407 an objective lens system 112
comprising the zoom lens system (roughly illustrated) of the
invention and an image pickup device chip 162 for receiving an
object image. These are built in the telephone handset 400.
[0216] It is here to be understood that an optical low-pass filter
F is additionally pasted onto the image pickup device chip 162 to
construct an integral image pickup unit 160. This image pickup unit
160 can be fitted in the rear end of a lens barrel 113 of the
objective lens system 112 in one-touch simple operation, so that
centering and alignment of the objective lens system 112 with
respect to the image pickup element chip 162 can be dispensed with
to make assembly simple. At the end of the lens barrel 113, there
is provided a cover glass 114 for protection of the objective lens
system 112. It is here to be understood that the zoom lens driving
mechanism in the lens barrel 113 is not shown.
[0217] The object image received at the image pickup device chip
162 is entered from a terminal 166 in a processing means (not
shown), and displayed as an electronic image on the monitor 404
and/or a monitor on the other end. To transmit an image to a person
on the other end, the processing means includes a signal processing
function of converting information about the object image received
at the image pickup element chip 162 to transmittable signals.
[0218] While various embodiments of the present invention have been
explained, it is understood that the invention is not necessarily
limited thereto, and so such various embodiments may be carried out
in combinations of two or more or modified in various manners
depending on the need of design.
[0219] According to the present invention as explained above, it is
thus possible to achieve a zoom lens system which enables an
associated lens mount to have a reduced thickness and receive the
zoom lens system with efficiency, and has a high magnification and
improved image-formation capabilities even upon rear focusing, and
makes it possible to reduce the thickness of a digital or video
camera as much as possible.
* * * * *