U.S. patent application number 12/218666 was filed with the patent office on 2008-11-27 for imaging system.
Invention is credited to Shinichi Mihara, Toru Miyajima, Yuji Miyauchi, Azusa Noguchi, Masahito Watanabe.
Application Number | 20080291297 12/218666 |
Document ID | / |
Family ID | 31931382 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080291297 |
Kind Code |
A1 |
Watanabe; Masahito ; et
al. |
November 27, 2008 |
Imaging system
Abstract
The invention relates to an imaging system in which, while high
image quality is maintained with the influence of diffraction
minimized, the quantity of light is controlled, and which enables
the length of the zoom lens to be cut down. The imaging system
comprises a zoom lens comprising a plurality of lens groups G1 and
G2 wherein the spacing between individual lens groups is varied to
vary a focal length and an aperture stop located in an optical path
for limiting at least an axial light beam diameter, and an
electronic image pickup device I located on the image side of the
zoom lens. The aperture stop has a fixed shape, and a filter S2 for
performing light quantity control by varying transmittance is
located on an optical axis of a space located at a position
different from that of a space in which the aperture stop is
located.
Inventors: |
Watanabe; Masahito; (Tokyo,
JP) ; Mihara; Shinichi; (Tokyo, JP) ; Noguchi;
Azusa; (Tokyo, JP) ; Miyajima; Toru; (Tokyo,
JP) ; Miyauchi; Yuji; (Tokyo, JP) |
Correspondence
Address: |
John C. Altmiller, Esq.;Kenyon & Kenyon
Suite 700, 1500 K Street, N.W.
Washington
DC
20005-1257
US
|
Family ID: |
31931382 |
Appl. No.: |
12/218666 |
Filed: |
July 16, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10619078 |
Jul 15, 2003 |
7414665 |
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12218666 |
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Current U.S.
Class: |
348/240.3 ;
348/E5.028; 348/E5.04; 348/E5.051 |
Current CPC
Class: |
H04N 9/04561 20180801;
G02B 15/144515 20190801; G02B 15/177 20130101; H04N 5/238 20130101;
H04N 5/2254 20130101; H04N 5/23293 20130101 |
Class at
Publication: |
348/240.3 ;
348/E05.051 |
International
Class: |
H04N 5/262 20060101
H04N005/262 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 16, 2002 |
JP |
2002-206733 |
Claims
1. An imaging system comprising a zoom lens comprising a plurality
of lens groups and an aperture stop located in an optical path for
limiting at least an axial light beam diameter, and an electronic
image pickup device located on an image side of the zoom lens,
wherein: said zoom lens comprises at least a first lens group
having negative refracting power, and a second lens group having
positive refracting power and located just after the first lens; a
spacing between the first lens group having negative refracting
power and the second lens group having positive refracting power
becomes narrower at a telephoto end than at a wide-angle end of
said zoom lens; said aperture stop has a fixed shape; said aperture
stop is located between an image-side surface in the first lens
group having negative refracting power and an object-side surface
in the second lens group having positive refracting power; said
aperture stop is such that a position where a perpendicular going
from said aperture stop down to the optical axis intersects the
optical axis is found within a lens medium in the lens groups; when
said focal length is varied, said aperture stop moves together with
the positive lens group; said aperture stop and said lens group of
positive refracting power are positioned more on the object side at
the telephoto end than at the wide-angle end; a filter for
implementing light quantity control by varying transmittance is
located on the optical axis; and said filter for implementing light
quantity control is located on an image plane side with respect to
said lens group of positive refracting power.
2. The imaging system according to claim 1, wherein said light
quantity control filter comprises at least one transmitting surface
wherein a central portion thereof has a transmittance higher than
that of a marginal portion thereof.
3. The imaging system according to claim 1, wherein said light
quantity control filter is tiltable with respect to the optical
axis.
4. The imaging system according to claim 1, wherein said aperture
stop is located in contact with the object-side surface in the
second lens group.
5. The imaging system according to claim 1, wherein said aperture
stop is formed of an aperture plate having an aperture on an
optical axis side.
6. The imaging system according to claim 1, wherein said first lens
group having negative refracting power is located nearest to the
object side of the zoom lens.
7. The imaging system according to claim 1, wherein said zoom lens
comprises, in order from the object side thereof, the first lens
group having negative refracting power and the second lens group
having positive refracting power, wherein lens groups movable for
zooming are defined by only two lens groups: the first lens group
having negative refracting power and the second lens group having
positive refracting power.
8. The imaging system according to claim 1, wherein said plurality
of lens groups consist of, in order from the object side thereof,
only two lens groups: the first lens group having negative
refracting power and the second lens group having positive
refracting power.
9. The imaging system according to claim 1, wherein said light
quantity control filter is located in an air space just after the
second lens group having positive refracting power, and when the
focal length is varied, said light quantity control filter moves
together with the second lens group.
10. The imaging system according to claim 1, wherein the aperture
stop is located in a variable space, both lens surfaces just before
and just after the aperture stop are concave on image sides
thereof, and the aperture stop has a funnel-form outside shape
concave on the image side off and off an optical axis.
11. The imaging system according to claim 1, wherein said light
quantity filter can be inserted in or de-inserted from an optical
path.
12. The imaging system according to claim 11, wherein, upon
retracting from an optical axis, said light quantity control filter
fluctuates in such a direction that a filter surface comes close to
the optical axis.
13. An imaging system comprising a zoom lens comprising a plurality
of lens groups and an aperture stop located in an optical path for
limiting at least an axial light beam diameter, and an electronic
image pickup device located on an image side of the zoom lens,
wherein: said zoom lens comprises at least a first lens group
having negative refracting power, and a second lens group having
positive refracting power and located just after the first lens; a
spacing between the first lens group having negative refracting
power and the second lens group having positive refracting power
becomes narrower at the telephoto end than at a wide-angle end of
said zoom lens; said aperture has a fixed shape; said aperture stop
is located between an image-side surface in the first lens group
having negative refracting power and an object-side surface in the
second lens group having positive refracting power; said aperture
stop is such that a position where a perpendicular going from said
aperture stop down to the optical axis intersects the optical axis
is found within a lens medium in the lens group; when said focal
length is varied, said aperture stop moves together with the
positive lens group; said aperture stop and said lens group of
positive refracting power are positioned more on the object side at
the telephoto end than at the wide-angle end; a shutter is located
in the optical axis; and said shutter is located on an image plane
side with respect to said lens group of positive refracting
power.
14. The imaging system according to claim 13, wherein said aperture
stop is located in contact with the object-side surface in the
second lens groups.
15. The imaging system according to claim 13, wherein said aperture
stop is formed of an aperture plate having an aperture on an
optical axis side.
16. The imaging system according to claim 13, wherein said first
lens group having negative refracting power is located nearest to
the object side of the zoom lens.
17. The imaging system according to claim 13, wherein said zoom
lens comprises, in order from the object side thereof, the first
lens group having negative refracting power and the second lens
group having positive refracting power, wherein lens groups movable
for zooming are defined by only two lens groups: the first lens
group having negative refracting power and the second lens group
having positive refracting power.
18. The imaging system according to claim 13, wherein said
plurality of lens groups consists of, in order from the object side
thereof, only two lens groups: the first lens group having negative
refracting power and the second lens group having positive
refracting power.
19. The imaging system according to claim 13, wherein said aperture
stop is located in an air space just before the lens group having
positive refracting power.
20. The imaging system according to claim 13, wherein said shutter
is located in an air space just after the second lens group having
positive refracting power, and wherein when the focal length is
varied, said shutter moves with the second lens group.
21. The imaging system according to claim 13, wherein said aperture
stop is located in a variable space, both lens surfaces just before
and just after the aperture stop are concave on images sides
thereof, and said aperture stop has a funnel-form outside shape
concave on the image side.
Description
[0001] This application is a continuation of prior U.S. patent
application Ser. No. 10/619,078, filed Apr. 18, 2006, and also
claims foreign priority benefits under 35 U.S.C. .sctn.119 of
Japanese Application No. 2002-206733, filed on Jul. 16, 2002, both
of which are expressly incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to an imaging
system, and specifically to an imaging system comprising a zoom
lens and an electronic image pickup device such as a CCD. More
specifically, the present invention is concerned with a digital
camera capable of obtaining electronic images.
[0003] So far, imaging systems incorporating a zoom lens and an
electronic image pickup device, for the most part, have made use of
a so-called variable stop with variable aperture diameter to
control the quantity of light passing through the zoom lens.
[0004] Current image pickup devices, on the other hand, are
designed with an increasing number of pixels for the purpose of
achieving image quality improvements.
[0005] The more the number of pixels in an image pickup device, the
higher the optical performance demanded for an optical system
becomes. A problem with the use of the conventional variable stop
is, however, that when it is intended to diminish the stop diameter
for light quantity control, resolution drops due to the influence
of diffraction. It is thus difficult to make any sensible tradeoff
between light quantity control and image quality improvements.
[0006] Even when it is desired to cut down the length of the zoom
lens, the thickness of the variable stop due to its mechanical
makeup often imposes limitations on reducing the length of the
optical system.
SUMMARY OF THE INVENTION
[0007] In view of such problems as stated above, the primary object
of the present invention is to provide an imaging system wherein
light quantity control as well as high image quality can be
achieved while the influence of diffraction is eliminated or
minimized, and the length of a zoom lens can be cut down.
[0008] According to the first aspect of the present invention, this
object is achievable by the provision of an imaging system
comprising a zoom lens comprising a plurality of lens groups
wherein a spacing between individual lens groups is varied to vary
a focal length and an aperture stop located in an optical path for
limiting at least an axial light beam diameter, and an electronic
image pickup device located on an image side of the zoom lens,
characterized in that:
[0009] the aperture stop has a fixed shape, and
[0010] a filter for performing light quantity control by varying
transmittance is located on an optical axis of a space located at a
position different from that of a space in which the aperture stop
is located.
[0011] Advantages of the first imaging system of the present
invention are now explained. This imaging system comprises a zoom
lens including a plurality of lens groups wherein the spacing
between individual lens groups is varied for zooming (variation of
the focal length) and an electronic image pickup device located on
the image side of the zoom lens. By fixing the shape of the stop,
it is possible to prevent deterioration in electronic images due to
diffracted light that occurs at a reduced stop diameter.
[0012] A conventional mechanism for controlling the quantity of
light at a stop position imposes limitations the flexibility in the
layout of the optical system due to the use of a shape variable
stop, etc. With the present invention wherein the stop of fixed
shape is used, however, the stop mechanism itself can be slimmed
down.
[0013] The spacing between the lens groups with the stop interposed
between them can be shorter than usual, and the length of the lens
group system can be cut down as well.
[0014] It is here understood that the aperture stop could be
located in the lens group, i.e., said aperture stop could be
located between lenses where the spacing between which remains
constant upon zooming. The aperture stop is not necessarily limited
to a circular one. It is here noted that for a conventional
variable stop that must be constantly of circular shape, a number
of stop plates are needed.
[0015] In the present invention, however, it is more preferable to
use an aperture stop having a circular aperture, because so-called
neatly blurred images with limited image variations at non-focused
portions can be obtained irrespective of in what state the quantity
of light is controlled.
[0016] It is also acceptable that the chief ray of an off-axis
light beam determined by the aperture stop is shaded at other
sites. In other words, the light quantity control means of the type
that the area of an aperture stop is commonly decreased must be
located at a position where there is no extreme decrease in the
quantity of light at the marginal area of a screen upon stop-down.
In the present invention, however, it is unnecessary to do so and
hence the degree of freedom in design can be enhanced.
[0017] If the aperture stop of fixed shape is configured as
described below, it is then possible to obtain electronic images of
high resolution.
[0018] According to the second aspect of the present invention, the
first imaging system is characterized in that when
1.5.times.10.sup.3.times.a/1 mm<F where F is a full-aperture
number at the telephoto end of the zoom lens and a is the minimum
pixel pitch in mm of the electronic image pickup device, the length
of the aperture stop in the vertical or horizontal direction of an
image pickup plane is longer than the length of the aperture stop
in the diagonal direction of the image pickup plane, or when
1.5.times.10.sup.3.times.a/1 mm>F, the length of the aperture
stop in the vertical or horizontal direction of the image pickup
plane is shorter than the length of the aperture stop in the
diagonal direction of the image pickup plane.
[0019] Advantages of the second imaging system of the present
invention are now explained. For instance, as the length of the
pixel pitch reaches about 2 .mu.m, there is diffraction limited at
an F-number of about 5.6. According to the present invention
wherein the stop is always of fixed shape, it is possible to
enhance resolution by the determination as desired of aperture
shape.
[0020] Suppose now that F is the F-number of the image pickup lens
used and .lamda. is the wavelength in nm of the light used. Then,
Rayleigh's critical frequency is roughly given by
1/1.22F.lamda.
[0021] On the other hand, the resolution limit of an image pickup
device comprising a plurality of pixels is given by 1/2a where a is
the pixel pitch in mm.
[0022] To keep Rayleigh's critical frequency from becoming lower
than the resolution limit of the image pickup device, it is a
requisite to satisfy
1.22F.lamda.<2a or F<1.64a/.lamda.
[0023] Assume here that the wavelength used is .lamda.=546 nm in
view of visible light photography. The condition for theoretical
F-number limit is given by
F<3.0.times.10.sup.3.times.a/1 mm
[0024] As the aperture is stopped down, on the other hand, it is
actually found that images start to deteriorate from a state
two-stop brighter than the aforesaid F-number.
[0025] Thus, it is more practical that the condition for the
F-number limit is given by
F<1.5.times.10.sup.3.times.a/1 mm
[0026] For an electronic image, improvements in its frequency
characteristics in the horizontal and vertical directions are
effective for image quality improvements. It is thus preferable
that when the full-aperture F-number is
1.5.times.10.sup.3.times.a/1 mm<F, the length of the aperture
stop in the vertical or horizontal direction of the image pickup
plane is longer than the length of the aperture stop in the
diagonal length of the image pickup plane so that the electronic
image is less susceptible to the influence of diffraction.
[0027] When the full-aperture F-number is
1.5.times.10.sup.3.times.a/1 mm>F, on the other hand, the length
of the aperture stop in the vertical or horizontal direction of the
image pickup plane should preferably be shorter than the length of
the aperture stop in the diagonal length of the image pickup plane
so that the electronic image is less susceptible to the influence
of geometrical aberrations.
[0028] With the second imaging system of the present invention, it
is further possible to make the cutoff frequency of a hitherto used
low-pass filter high or dispense with that low pass-filter
itself.
[0029] In the present invention, it is desired to cut down the
length of the lens system as follows.
[0030] According to the third aspect of the present invention, the
first imaging system is further characterized in that the filter is
located in the minimum air space among variable air spaces in the
zoom lens or in the longest air space among constant air spaces in
the zoom lens.
[0031] With the third imaging system of this arrangement, the
filter can be located in a constantly wide space in the zooming
zone, so that the length of the lens system can favorably be cut
down. As described later, the same is true for even the case where
the shutter is located. That is, the third imaging system of the
present invention may be embodied as follows.
[0032] Specifically, there is provided an imaging system which
comprises a zoom lens comprising a plurality of lens groups in
which the spacing between individual lens groups is varied for
varying a focal length and an aperture stop located in an optical
path to limit at least the diameter of an axial light beam and an
electronic image pickup device located on the image side of the
zoom lens, said aperture stop being of fixed shape, and which
further comprises a shutter located on an optical axis of a space
at a position different from that in which the aperture stop is
located, characterized in that the shutter is located in the
minimum air space among variable air spaces in the zoom lens or in
the longest air space among constant air spaces in the zoom
lens.
[0033] It is here noted that as the size of the aperture stop
having fixed shape is increased to ensure the quantity of light,
the light beam is shaded by a lens barrel or the like. This often
leads to variations of brightness between the central area and the
marginal area of an image. According to the present invention, the
brightness variations should desirously be reduced by use of such a
light quantity control filter as explained below.
[0034] According to the fourth aspect of the present invention, the
first imaging system is further characterized in that the light
quantity control filter comprises at least one transmitting surface
wherein the transmittance of its central portion is higher than
that of its marginal portion.
[0035] This arrangement makes photography with reduced brightness
variations feasible.
[0036] According to the present invention, it is preferable to
reduce ghosts due to light reflected at the filter as follows.
[0037] According to the fifth aspect of the present invention, the
first imaging system is further characterized in that the light
quantity control filter is tiltable with respect to the optical
axis.
[0038] According to the sixth aspect of the present invention, the
first imaging system is further characterized in that the aperture
stop is located between lens groups between which there is an air
space variable upon zooming or focusing, and the light quantity
control filter is located at a position different from the air
space.
[0039] With the sixth imaging system of such construction, the
amount of movement of the lens groups upon zooming can be so
increased that high zoom ratios are easily achievable.
[0040] According to the seventh aspect of the present invention,
any one of the 1st to 6th imaging systems is further characterized
in that the aperture stop is positioned such that a perpendicular
going from the aperture stop down to the optical axis intersects
the optical axis within a lens medium in the lens groups.
[0041] Since the aperture shape of the aperture stop is of
invariable shape, it is possible to achieve such an arrangement,
whereby much more size reductions are achievable.
[0042] According to the eighth aspect of the present invention, the
seventh imaging system is further characterized in that the
aperture stop is located in contact with any one of lens surfaces
in the lens groups.
[0043] With the arrangement of the eighth imaging system, any stop
alignment is so dispensed with that higher accuracy is achievable.
In particular, it is easier to obtain the stop by the optical black
painting of a lens surface.
[0044] According to the ninth aspect of the present invention, any
one of the 1st to 8th imaging systems is further characterized in
that the aperture stop is formed of an aperture plate having an
aperture on the optical axis side.
[0045] With the arrangement of the ninth imaging system, the stop
can be made thin.
[0046] According to the 10th aspect of the present invention, any
one of the 1st to 9th imaging systems is further characterized in
that:
[0047] the zoom lens comprises at least a lens group having
negative refracting power and a lens group located just after the
same with positive refracting power, wherein the spacing between
the lens group having negative refracting power and the lens group
having positive refracting power becomes narrower at the telephoto
end than at the wide-angle end of the zoom lens,
[0048] the aperture stop is located between the surface nearest to
the image side in the lens group having negative refracting power
and the image side-surface in the lens group having positive
refracting power, and the light quantity control filter is located
on the image plane side with respect to the aperture stop.
[0049] Advantages of the 10th imaging system of the present
invention are now explained. When the negative lens group and the
positive lens group are arranged in this order to form the zoom
lens, it is preferable to interpose the aperture stop between the
surface nearest to the image side of the zoom lens in the negative
lens group and the surface, which faces the image side of the zoom
lens, in the positive lens group, because the whole zoom lens can
be made compact and it is easy to ensure the angle of view at the
wide-angle end.
[0050] With the aperture stop located at such a position, the
spreading of a light beam from there toward the image side does not
become overly large, so that the light quantity control filter can
be positioned on the image side with respect to the aperture stop.
This is advantageous for size reductions because the filter itself
can be made compact.
[0051] More specifically, according to the 11th aspect of the
present invention, the 10th imaging system is further characterized
in that the lens group having negative refracting power is located
nearest to the object side of the zoom lens.
[0052] With the 11th imaging system of such construction, it is
possible to achieve any of wide-angle arrangements, high zoom
ratios, and size reductions.
[0053] More preferably, according to the 12th aspect of the present
invention, the 10th imaging system is further characterized in that
the zoom lens comprises, in order from its object side, the lens
group having negative refracting power and the lens group having
positive refracting power, wherein lens groups movable for zooming
are defined by only two lens groups, i.e., the lens group having
negative refracting power and the lens group having positive
refracting power.
[0054] With the 12th imaging system of such a lens arrangement, it
is possible to achieve any of wide-angle arrangements, high zoom
ratios, and size reductions.
[0055] More preferably, according to the 13th aspect of the present
invention, the 10th imaging system is further characterized in that
the plurality of lens groups consist of, in order from its object
side, only two lens groups, i.e., the lens group having negative
refracting power and the lens group having positive refracting
power.
[0056] With the 13th imaging system of such a lens arrangement, the
construction of the zoom lens can be much more simplified.
[0057] According to the 14th aspect of the present invention, any
one of the 10th to 13th imaging systems is further characterized in
that the aperture stop is located in an air space just before the
positive lens group having positive refracting power.
[0058] With the 14th imaging system of such a lens arrangement,
light rays incident on the image pickup device can be as vertical
to the image pickup plane as possible. Especially when the negative
and the positive lens group are arranged in this order from the
object side of the zoom lens, the negative lens group that is the
first lens group can be located much nearer to the second lens
group at the telephoto end, thereby making the length of the zoom
lens much shorter relative to the amount of a decrease in the
spacing between the first lens group and the second lens group.
[0059] With the aperture stop designed to move in unison with the
lens group having positive refracting power, the construction of
the lens barrel can be much more simplified.
[0060] According to the 15th aspect of the present invention, any
one of the 10th to 14th imaging systems is further characterized in
that the light quantity control filter is located in an air space
just after the lens group having positive refracting power.
[0061] The 15th imaging system of such a lens arrangement is more
preferable in that the filter is located at a position where a
light beam does not largely spread out. This is particularly
preferable for a two-group zoom lens comprising a negative lens
group and a positive lens group because the light beam does not
largely spread out.
[0062] According to the 16th aspect of the present invention, any
one of the 1st to 15th imaging systems is further characterized by
constantly satisfying the following condition (1):
0.01<.alpha./.beta.<1.3 (1)
where .alpha. is the axial distance from the aperture stop to the
entrance surface of the light quantity control filter located on
the image side with respect thereto, and .beta. is the axial
distance from the entrance surface of the light quantity control
filter to the image pickup plane of the electronic image pickup
device.
[0063] Advantages of, and requirements for, the 16th imaging system
of the present invention are now explained. The location of the
filter near to the aperture stop is more preferable in that the
size of the filter itself can be diminished. As the upper limit of
1.3 to condition (1) is exceeded, it is difficult to make the
filter small. As the lower limit of 0.01 is not reached, on the
other hand, the stop is too close to the filter, rendering it
difficult to make the whole zoom lens compact.
[0064] The lower limit to condition (1) should be preferably 0.1
and more preferably 0.2, and the upper limit preferably 1.0, more
preferably 0.8 and even more preferably 0.6.
[0065] Desirously, this condition should be satisfied all over the
zooming zone or, alternatively, at least at the position where the
stop is nearest to the image side in the zooming zone.
[0066] According to the 17th aspect of the present invention, any
one of the 1st to 16th imaging systems is characterized by
satisfying the following condition (2):
0.5<.phi./.beta./.phi..alpha.<1.5 (2)
where .phi..alpha. is the maximum diameter of the aperture in the
aperture stop and .phi..beta. is the maximum effective diameter
(diagonal length) of the light quantity control filter.
[0067] The 17th imaging system of the present invention should
preferably be constructed in such a way as to satisfy condition
(2). As the lower limit of 0.5 is not reached, a light beam used
for picking up images is highly likely to be shaded. As the upper
limit of 1.5 is exceeded, on the other hand, the size of the filter
becomes large.
[0068] The lower limit to condition (2) should be preferably 0.7
and more preferably 0.8, and the upper limit preferably 1.2 and
more preferably 1.05.
[0069] Desirously, this condition (2) should be satisfied all over
the zooming zone or, alternatively, at least at the position where
the stop is nearest to the image side in the zooming zone.
[0070] According to the 18th aspect of the present invention, any
one of the 1st to 17th imaging systems is further characterized in
that the aperture stop is located in a variable space, both the
lens surfaces just before and just after the aperture stop are
concave on their image sides, and the aperture stop has a
funnel-form outside shape concave toward the image side off and off
the optical axis.
[0071] With the 18th imaging system of such a lens arrangement, the
outside shape of the stop is configured following the contours of
the lens surfaces just before and just after the stop so that both
the lens surfaces can be nearer to the stop. It is understood that
a lens surface having an optically blacked outside shape, too, is
embraced in this conception.
[0072] According to the 19th aspect of the present invention, any
one of the 1st to 18th imaging systems is further characterized in
that the light quantity control filter can be inserted in or
de-inserted from an optical path.
[0073] More preferably, according to the 20th aspect of the present
invention, the 19th imaging system is further characterized in
that, upon retracting from an optical axis, the light quantity
control filter fluctuates in such a direction that the filter
surface is parallel and close to the optical axis.
[0074] With the 20th imaging system of such construction, size
reductions are achievable because it is unnecessary to make space
allowed for the retraction of the filter around the zoom lens large
away from the optical axis.
[0075] The present invention has been described specifically with
reference to the light quantity control filter. In some cases,
however, the prior art variable stop has also a shutter role. In
those cases, instead of the filter or in addition to the filter, it
is preferable to locate a shutter in the vicinity of the filter.
Alternatively, it is acceptable to locate the filter and the
shutter in another space with at least one lens interposed between
them.
[0076] For instance, such embodiments as mentioned below are
envisaged. The respective advantages are much the same except that
the shutter is used instead of the filter.
[0077] According to the 21st aspect of the present invention, there
is provided an imaging system comprising a zoom lens comprising a
plurality of lens groups wherein a spacing between individual lens
groups is varied to vary a focal length and an aperture stop
located in an optical path for limiting at least an axial light
beam diameter, and an electronic image pickup device located on an
image side of the zoom lens, characterized in that:
[0078] the aperture stop has a fixed shape, and
[0079] a shutter is located on an optical axis of a space located
at a position different from that of a space in which the aperture
stop is located.
[0080] According to the 22nd aspect of the present invention, the
21st imaging system is further characterized in that the aperture
stop is located between lens groups between which there is an air
space variable upon zooming or focusing, and the shutter is located
at a position different from the air space.
[0081] According to the 23rd aspect of the present invention, the
21st or the 22nd imaging system is further characterized in that
the aperture stop is positioned such that a perpendicular going
from the aperture stop down to the optical axis intersects the
optical axis within a lens medium in the lens groups.
[0082] According to the 24th aspect of the present invention, the
23rd imaging system is further characterized in that the aperture
stop is located in contact with any one of lens surfaces in the
lens groups.
[0083] According to the 25th aspect of the present invention, any
one of the 21st to 24th imaging systems is further characterized in
that the aperture stop is formed of an aperture plate having an
aperture on an optical axis side.
[0084] According to the 26th aspect of the present invention, any
one of the 21st to 25th imaging systems is further characterized in
that:
[0085] the zoom lens comprises at least a lens group having
negative refracting power and a lens group located just after the
same with positive refracting power, wherein the spacing between
the lens group having negative refracting power and the lens group
having positive refracting power becomes narrower at the telephoto
end than at the wide-angle end of the zoom lens,
[0086] the aperture stop is located between the surface nearest to
the image side in the lens group having negative refracting power
and the image side-surface in the lens group having positive
refracting power, and
[0087] the shutter is located on the image plane side with respect
to the aperture stop.
[0088] According to the 27th aspect of the present invention, the
26th imaging system is further characterized in that the lens group
having negative refracting power is located nearest to the object
side of the zoom lens.
[0089] According to the 28th aspect of the present invention, the
26th imaging system is further characterized in that the zoom lens
comprises, in order from its object side, the lens group having
negative refracting power and the lens group having positive
refracting power, wherein lens groups movable for zooming are
defined by only two lens groups, i.e., the lens group having
negative refracting power and the lens group having positive
refracting power.
[0090] According to the 29th aspect of the present invention, the
26th imaging system is further characterized in that the plurality
of lens groups consist of, in order from its object side, only two
lens groups, i.e., the lens group having negative refracting power
and the lens group having positive refracting power.
[0091] According to the 30th aspect of the present invention, any
one of the 26th to 29th imaging systems is further characterized in
that the aperture stop is located in an air space just before the
lens group having positive refracting power.
[0092] According to the 31st aspect of the present invention, any
one of the 26th to 30th imaging systems is further characterized in
that the shutter is located in an air space just after the lens
group having positive refracting power.
[0093] According to the 32nd aspect of the present invention, any
one of the 21st to 31st imaging systems is further characterized by
constantly satisfying the following condition (3):
0.01<.alpha.'/.beta.'<1.3 (3)
where .alpha.' is the axial distance from the aperture stop to the
shutter located on the image side with respect thereto, and .beta.'
is the axial distance from the shutter to the image pickup plane of
the electronic image pickup device.
[0094] The lower limit to condition (3) should be preferably 0.1
and more preferably 0.2, and the upper limit preferably 1.0, more
preferably 0.8 and even more preferably 0.6.
[0095] Desirously, this condition should be satisfied all over the
zooming zone or, alternatively, at least at the position where the
stop is nearest to the image side in the zooming zone.
[0096] According to the 33rd aspect of the present invention, any
one of the 21st to 32nd imaging systems is characterized by
satisfying the following condition (4):
0.5<.phi..beta.'/.phi..alpha.'<1.5 (4)
where .phi..alpha.' is the maximum diameter of the aperture in the
aperture stop and .phi..beta.' is the maximum effective diameter
(diagonal length) of the shutter.
[0097] The lower limit to condition (4) should be preferably 0.7
and more preferably 0.8, and the upper limit preferably 1.2 and
more preferably 1.05.
[0098] Desirously, this condition (4) should be satisfied all over
the zooming zone or, alternatively, at least at the position where
the stop is nearest to the image size in the zooming zone.
[0099] According to the 34th aspect of the present invention, any
one of the 21st to 33rd imaging systems is further characterized in
that the aperture stop is located in a variable space, both the
lens surfaces just before and just after the aperture stop are
concave on their image sides, and the aperture stop has a
funnel-form outside shape concave toward the image side off and off
the optical axis.
[0100] Still other objects and advantages of the invention will in
part be obvious and will in part be apparent from the
specification.
[0101] 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
[0102] FIGS. 1(a), 1(b) and 1(c) are illustrative in section of
Example 1 of the zoom lens used with the imaging system of the
invention at the wide-angle end upon focused on an infinite object
point.
[0103] FIGS. 2(a), 2(b) and 2(c) are views for Example 2 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0104] FIGS. 3(a), 3(b) and 3(c) are views for Example 3 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0105] FIGS. 4(a), 4(b) and 4(c) are views for Example 4 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0106] FIGS. 5(a), 5(b) and 5(c) are views for Example 5 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0107] FIGS. 6(a), 6(b) and 6(c) are views for Example 6 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0108] FIGS. 7(a), 7(b) and 7(c) are views for Example 7 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0109] FIGS. 8(a), 8(b) and 8(c) are views for Example 8 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0110] FIGS. 9(a), 9(b) and 9(c) are views for Example 9 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0111] FIGS. 10(a), 10(b) and 10(c) are views for Example 10 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0112] FIGS. 11(a), 11(b) and 11(c) are views for Example 11 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0113] FIGS. 12(a), 12(b) and 12(c) are views for Example 12 of the
zoom lens, similar to FIGS. 1(a), 1(b) and 1(c).
[0114] FIGS. 13(a), 13(b) and 13(c) are aberration diagrams for
Example 1 upon focused on an infinite object point.
[0115] FIGS. 14(a), 14(b) and 14(c) are aberration diagrams for
Example 2 upon focused on an infinite object point.
[0116] FIGS. 15(a), 15(b) and 15(c) are aberration diagrams for
Example 3 upon focused on an infinite object point.
[0117] FIGS. 16(a), 16(b) and 16(c) are aberration diagrams for
Example 4 upon focused on an infinite object point.
[0118] FIGS. 17(a), 17(b) and 17(c) are aberration diagrams for
Example 5 upon focused on an infinite object point.
[0119] FIGS. 18(a), 18(b) and 18(c) are aberration diagrams for
Example 6 upon focused on an infinite object point.
[0120] FIGS. 19(a), 19(b) and 19(c) are aberration diagrams for
Example 7 upon focused on an infinite object point.
[0121] FIGS. 20(a), 20(b) and 20(c) are aberration diagrams for
Example 8 upon focused on an infinite object point.
[0122] FIGS. 21(a), 21(b) and 21(c) are aberration diagrams for
Example 9 upon focused on an infinite object point.
[0123] FIGS. 22(a), 22(b) and 22(c) are aberration diagrams for
Example 10 upon focused on an infinite object point.
[0124] FIGS. 23(a), 23(b) and 23(c) are aberration diagrams for
Example 11 upon focused on an infinite object point.
[0125] FIGS. 24(a), 24(b) and 24(c) are aberration diagrams for
Example 12 upon focused on an infinite object point.
[0126] FIG. 25 is illustrative of the transmittance characteristics
of one example of a near-infrared sharp cut coat.
[0127] FIG. 26 is illustrative of the transmittance characteristics
of one example of a color filter located on the exit surface side
of a low-pass filter.
[0128] FIG. 27 is illustrative of how color filter elements are
arranged for a complementary colors filter.
[0129] FIG. 28 is illustrative of one example of the wavelength
characteristics of the complementary colors filter.
[0130] FIGS. 29(a), 29(b) and 29(c) are illustrative of a fixed
stop used with the zoom lens of the invention comprising a fixed
stop and a filter or a shutter, especially examples of the shape of
that fixed stop when it is larger than the theoretical F-number
limit.
[0131] FIGS. 30(a), 30(b) and 30(c) are illustrative of a fixed
stop used with the zoom lens of the invention comprising a fixed
stop and a filter or a shutter, especially examples of the shape of
that fixed stop when it is smaller than the theoretical F-number
limit.
[0132] FIG. 31 is illustrative of one exemplary funnel-form fixed
stop.
[0133] FIG. 32 is illustrative of a turret-form light quantity
control filter that can be used in the invention.
[0134] FIG. 33 is illustrative of one example of a filter that
reduces variations of light quantity.
[0135] FIG. 34 is illustrative of one example of a filter that can
be inserted in or de-inserted from an optical path by fluctuation
(rocking or swaying movement).
[0136] FIG. 35 is illustrative of the structure for insertion or
de-insertion by fluctuation of a filter for reducing ghosts due to
reflected light.
[0137] FIG. 36 is a front and a rear view of one example of a
rotary focal plane shutter.
[0138] FIGS. 37(a), 37(b), 37(c) and 37(d) are illustrative of how
the rotary shutter curtain of the shutter of FIG. 36 is
rotated.
[0139] FIG. 38 is a front perspective view illustrative of the
appearance of a digital camera incorporating the zoom lens of the
invention.
[0140] FIG. 39 is a rear perspective view of the digital camera of
FIG. 38.
[0141] FIG. 40 is a sectional schematic of the digital camera.
[0142] FIG. 41 is a front perspective view of a personal computer
in use, in which the zoom lens of the invention is incorporated as
an objective optical system.
[0143] FIG. 42 is a sectional view of a phototaking optical system
in the personal computer.
[0144] FIG. 43 is a side view of the state of FIG. 41.
[0145] FIGS. 44(a) and 44(b) are a front and a side view of a
cellular phone incorporating the zoom lens of the invention as an
objective optical system, and FIG. 44(c) is a sectional view of an
phototaking optical system for the same.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0146] First of all, Examples 1 to 12 of the zoom lens used with
the imaging system of the invention are explained. FIGS. 1 to 12
are sectional views of these zoom lenses at the wide-angle end (a),
in an intermediate state (b) and at the telephoto end (c) upon
focused on an infinite object point. In FIGS. 1 to 12, the first
lens group is indicated by G1, the second lens group by G2, the
third lens group by G3, the fourth lens group by G4, an optical
path-bending prism by P, a low-pass filter having a near-infrared
sharp cut coat by F, a cover glass for a CCD that is an electronic
image pickup device by C, a plane-parallel plate that integrates
the low-pass filter with the CCD cover glass and has a wavelength
selective coat by F', and an image plane of the CCD by I. The
optical low-pass filter F and the cover glass C located in order
from the object side is fixed between the second G2 or the fourth
lens group G4 and the image plane I. The light quantity control
(ND) filter or shutter position is indicated by N. It is acceptable
to use both the light quantity control filter and the light
quantity control shutter.
Example 1
[0147] As shown in FIG. 1, the zoom lens of Example 1 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the image plane side and the second lens group G2 moves
toward the object side while the spacing between the first lens
group G1 and the second lens group G2 becomes narrow.
[0148] In Example 1, the first lens group G1 is made up of a
double-concave lens and a positive meniscus lens convex on its
object side. The second lens group G2 is made up of a stop, a
double-convex lens located in the rear thereof and a negative
meniscus lens convex on its object side. Aspheric surfaces are used
for all of eight lens surfaces.
[0149] Then, the light quantity control filter or shutter is
located at a position 1 mm farther off the image side-surface of
the negative meniscus lens in the second lens group G2 in such a
way that it moves axially together with the second lens group
G2.
Example 2
[0150] As shown in FIG. 2, the zoom lens of Example 2 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the image plane side and the second lens group G2 moves
toward the object side with a narrowing space between them.
[0151] In Example 2, the first lens group G1 is made up 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 made up of a stop, a double-convex lens located in the rear
thereof and a negative meniscus lens convex on its object side.
Aspheric surfaces are used for all of eight lens surfaces.
[0152] Then, the light quantity control filter or shutter is
located at a position 1.5 mm farther off the image side-surface of
the negative meniscus lens in the second lens group G2 in such a
way that it moves axially together with the second lens group
G2.
Example 3
[0153] As shown in FIG. 3, the zoom lens of Example 3 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the object side along a concave locus and comes nearer to
the image plane side at the telephoto end than at the wide-angle
end. The second lens group G2 moves toward the object side with a
narrowing space between the first lens group G1 and the second lens
group G2.
[0154] In Example 3, the first lens group G1 consists of a
double-concave lens and a positive meniscus lens convex on its
object side, and the second lens group G2 consists of a stop, a
double-convex lens located in the rear thereof and a negative
meniscus lens convex on its object side. Aspheric surfaces are used
for all of eight lens surfaces.
[0155] Then, the light quantity control filter or shutter is
located at a position 1.5 mm farther off the image side-surface of
the negative meniscus lens in the second lens group G2 in such a
way that it moves axially together with the second lens group
G2.
Example 4
[0156] As shown in FIG. 4, the zoom lens of Example 4 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the object side along a concave locus and comes nearer to
the image plane side at the telephoto end than at the wide-angle
end. The second lens group G2 moves toward the object side with a
narrowing space between the first lens group G1 and the second lens
group G2.
[0157] In Example 4, the first lens group G1 consists of a
double-concave lens and a positive meniscus lens convex on its
object side, and the second lens group G2 consists of a stop, a
double-convex lens located in the rear thereof and a negative
meniscus lens convex on its object side. Aspheric surfaces are used
for all of eight lens surfaces.
[0158] Then, the light quantity control filter or shutter is
located at a position 1.5 mm farther off the image side-surface of
the negative meniscus lens in the second lens group G2 in such a
way that it moves axially together with the second lens group
G2.
Example 5
[0159] As shown in FIG. 5, the zoom lens of Example 5 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the image plane side and the second lens group G2 moves
toward the object side while the spacing between the first lens
group G1 and the second lens group G2 becomes narrow.
[0160] In Example 5, the first lens group G1 consists of a negative
meniscus lens convex on its object side and a positive meniscus
lens convex on its object side, and the second lens group G2
consists of a stop, a double-convex lens located in the rear
thereof and a negative meniscus lens convex on its object side.
Aspheric surfaces are used for all of eight lens surfaces.
[0161] Then, the light quantity control filter or shutter is
located at a position 1.0 mm farther off the image side-surface of
the negative meniscus lens in the second lens group G2 in such a
way that it moves axially together with the second lens group
G2.
Example 6
[0162] As shown in FIG. 6, the zoom lens of Example 6 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the image plane side and the second lens group G2 moves
toward the object side while the spacing between the first lens
group G1 and the second lens group G2 becomes narrow.
[0163] In Example 6, the first lens group G1 consists of a
double-concave lens and a positive meniscus lens convex on its
object side, and the second lens group G2 consists of a stop, a
double-convex lens located in the rear thereof and a double-concave
lens. Aspheric surfaces are used for all of eight lens
surfaces.
[0164] Then, the light quantity control filter or shutter is
located at a position 1.5 mm farther off the image side-surface of
the double-concave lens in the second lens group G2 in such a way
that it moves axially together with the second lens group G2.
Example 7
[0165] As shown in FIG. 7, the zoom lens of Example 7 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the image plane side and the second lens group G2 moves
toward the object side while the spacing between the first lens G1
and the second lens group G2 becomes narrow.
[0166] In Example 7, the first lens group G1 consists of a
double-concave lens and a positive meniscus lens convex on its
object side, and the second lens group G2 consists of a stop, a
double-convex lens located in the rear thereof and a double-concave
lens. Aspheric surfaces are used for all of eight lens
surfaces.
[0167] Then, the light quantity control filter or shutter is
located at a position 1.5 mm farther off the image side-surface of
the double-concave lens in the second lens group G2 in such a way
that it moves axially together with the second lens group G2.
Example 8
[0168] As shown in FIG. 8, the zoom lens of Example 8 is built up
of a first lens group G1 composed of a negative meniscus lens
convex on its object side, an optical-path bending prism P, a
negative meniscus lens convex on its object side and a positive
meniscus lens convex on its object side, a second lens group G2
composed of an aperture stop and a doublet consisting of a
double-convex positive lens and a negative meniscus lens convex on
its image plane side, a third lens group G3 composed of a positive
meniscus lens convex on its object side and a doublet consisting of
a planoconvex positive lens and a planoconcave lens, and a fourth
lens group G4 composed of one double-convex positive lens. For
zooming from the wide-angle end to the telephoto end of the zoom
lens, the first lens group G1 remains fixed, the second lens group
G2 moves monotonously toward the object side, the third lens group
G3 moves monotonously toward the object side in such a way that its
spacing with the second lens group G2 becomes wide and then narrow,
and the fourth lens group G4 remains fixed. For focusing on a
nearby subject, the third lens group G3 moves toward the object
side.
[0169] Three aspheric surfaces are used, one at the image plane
side-surface of the negative meniscus lens in the rear of the
optical path-bending prism P in the first lens group G1, one at the
object side-surface of the positive meniscus lens in the third lens
group G3, and one at the image plane side-surface of the
double-convex positive lens in the fourth lens group G4.
[0170] Then, the light quantity control filter or shutter is
located 1.0 mm farther off the object side of the positive meniscus
lens in the third lens group G3 in such a way that it moves axially
together with the third lens group G3.
Example 9
[0171] As shown in FIG. 9, the zoom lens of Example 9 is made up of
a first lens group G1 having negative refracting power and a second
lens group G2 having positive refracting power. For zooming from
the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the object side along a concave locus and comes nearer to
the image plane side at the telephoto end than at the wide-angle
end, and the second lens group G2 moves toward the object side. In
the meantime, the spacing between the first lens group G1 and the
second lens group G2 becomes narrow.
[0172] In Example 9, 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, and the second lens group
G2 is composed of a stop and a triplet consisting of a positive
meniscus lens convex on its object side, located in the rear
thereof, a negative meniscus lens convex on its object side and a
double-convex positive lens. The stop has a round shape as viewed
from its entrance side, and is formed by optically blacking the
entrance convex surface in the second lens group G2. Thus, the stop
is located at a position N on the image side with respect to the
entrance side surface vertex in the second lens group G2, and the
spacing between the stop and the entrance convex surface in the
numerical data given later has a minus value. Three aspheric
surfaces are used, one at the image plane side-surface of the
negative meniscus lens in the first lens group G1, one at the
object side-surface of the triplet in the second lens group G2 and
one at the image plane side-surface of the triplet in the second
lens group G2.
[0173] Then, the light quantity control filter or shutter is
located 1.0 mm farther off the image side of the triplet in the
second lens group G2 in such a way that it moves axially together
with the second lens group G2.
Example 10
[0174] As shown in FIG. 10, the zoom lens of Example 10 is made up
of a first lens group G1 having negative refracting power and a
second lens group G2 having positive refracting power. For zooming
from the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the image plane side, and the second lens group G2 moves
toward the object side. In the meantime, the spacing between the
first lens group G1 and the second lens group G2 becomes
narrow.
[0175] In Example 10, 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, and the second lens group
G2 is composed of a stop, a doublet consisting of a positive
meniscus lens convex on its object side, located on in the rear
thereof and a negative meniscus lens convex on its object side and
a positive single lens. The stop has a round shape as viewed from
its entrance side, and is formed by optically blacking the entrance
convex surface in the second lens group G2. Thus, the stop is
located at a position N on the image side with respect to the
entrance side surface vertex in the second lens group G2, and the
spacing between the stop and the entrance convex surface in the
numerical data given later has a minus value. Two aspheric surfaces
are used, one at the image plane side-surface of the negative
meniscus lens in the first lens group G1, and another at the
surface located nearest to the object side in the second lens group
G2.
[0176] Then, the light quantity control filter or shutter is
located 1.0 mm farther off the image side of the positive single
lens in the second lens group G2 in such a way that it moves
axially together with the second lens group G2.
Example 11
[0177] As shown in FIG. 11, the zoom lens of Example 11 is made up
of a first lens group G1 having negative refracting power and a
second lens group G2 having positive refracting power. For zooming
from the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the object side along in a concave locus, and comes nearer
to the image plane side at the telephoto end than at the wide-angle
end, and the second lens group G2 moves toward the object side. In
the meantime, the spacing between the first lens group G1 and the
second lens group G2 becomes narrow.
[0178] In Example 11, the first lens group G1 consists of a
negative meniscus lens convex on its object side and a positive
meniscus lens convex on its object side, and the second lens group
G2 consists of a stop, a double-convex positive lens located in the
rear thereof and a negative meniscus lens convex on its object
side. The stop has a round shape as viewed from its entrance side,
and is formed by optically blacking the entrance convex surface in
the second lens group G2. Thus, the stop is located at a position N
on the image side with respect to the entrance side surface vertex
in the second lens group G2, and the spacing between the stop and
the entrance convex surface in the numerical data given later has a
minus value. Aspheric surfaces are used for all of eight lens
surfaces.
[0179] Then, the light quantity control filter or shutter is
located 1.5 mm farther off the image side of the negative meniscus
lens in the second lens group G2 in such a way that it moves
axially together with the second lens group G2.
Example 12
[0180] As shown in FIG. 12, the zoom lens of Example 12 is made up
of a first lens group G1 having negative refracting power and a
second lens group G2 having positive refracting power. For zooming
from the wide-angle end to the telephoto end of the zoom lens upon
focused on an infinite object point, the first lens group G1 moves
toward the image plane side, and the second lens group G2 moves
toward the object side. In the meantime, the spacing between the
first lens group G1 and the second lens group G2 becomes
narrow.
[0181] In Example 12, the first lens group G1 consists of a
negative meniscus lens convex on its object side and a positive
meniscus lens convex on its object side, and the second lens group
G2 consists of a stop, a double-convex positive lens located in the
rear thereof and a negative meniscus lens convex on its object
side. The stop has a round shape as viewed from its entrance side,
and is formed by optically blacking the entrance convex surface in
the second lens group G2. Thus, the stop is located at a position N
on the image side with respect to the entrance side surface vertex
in the second lens group G2, and the spacing between the stop and
the entrance convex surface in the numerical data given later has a
minus value. Four aspheric surfaces are used, two at both surfaces
of the negative meniscus lens in the first lens group G1 and two at
both surfaces of the double-convex positive lens in the second lens
group G2.
[0182] Then, the light quantity control filter or shutter is
located 1.0 mm farther off the image side of the negative meniscus
lens in the second lens group G2 in such a way that it moves
axially together with the second lens group G2.
[0183] The numerical data on each example are given below. Symbols
used hereinafter but not hereinbefore have the following
meanings:
f: focal length of the zoom lens 2.omega.: angle of view
F.sub.NO: F-number
[0184] WE: wide-angle end ST: intermediate state TE: telephoto end
r.sub.1, r.sub.2, . . . : radius of curvature of each lens surface
d.sub.1, d.sub.2, . . . : spacing between adjacent lens surfaces
n.sub.d1, n.sub.d2, . . . : d-line refractive index of each lens
V.sub.d1, V.sub.d2, . . . : Abbe number of each lens
[0185] Here let x be an optical axis on condition that the
direction of propagation of light is positive and y be a direction
orthogonal to the optical axis. Then, aspheric 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.s-
up.6+A.sub.8y.sup.8+A.sub.10y.sup.10
where r is a 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 aspheric coefficients,
respectively.
Example 1
TABLE-US-00001 [0186] r.sub.1 = -12.193 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.78800 .nu..sub.d1 = 47.37 r.sub.2 = 10.585 (Aspheric)
d.sub.2 = 1.14 r.sub.3 = 6.202 (Aspheric) d.sub.3 = 0.84 n.sub.d2 =
1.84666 .nu..sub.d2 = -23.78 r.sub.4 = 7.845 (Aspheric) d.sub.4 =
(Variable) r.sub.5 = .infin. (Stop) d.sub.5 = 0.80 r.sub.6 = 3.456
(Aspheric) d.sub.6 = 3.10 n.sub.d3 = 1.69350 .nu..sub.d3 = 53.21
r.sub.7 = -5.866 (Aspheric) d.sub.7 = 0.00 r.sub.8 = 59.892
(Aspheric) d.sub.8 = 0.80 n.sub.d4 = 1.80518 .nu..sub.d4 = 25.42
r.sub.9 = 3.400 (Aspheric) d.sub.9 = (Variable) d.sub.10 = .infin.
d.sub.10 = 1.44 n.sub.d5 = 1.54771 .nu..sub.d5 = 62.84 r.sub.11 =
.infin. d.sub.11 = 0.80 r.sub.12 = .infin. d.sub.12 = 0.80 n.sub.d6
= 1.51633 .nu..sub.d6 = 64.14 r.sub.13 = .infin. d.sub.13 = 1.00
r.sub.14 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 0.000 A.sub.4 = 7.28875 .times. 10.sup.-3 A.sub.6 =
-3.16079 .times. 10.sup.-4 A.sub.8 = 5.59240 .times. 10.sup.-6
A.sub.10 = 0 2nd surface K = 0.000 A.sub.4 = 6.08993 .times.
10.sup.-3 A.sub.6 = 7.92220 .times. 10.sup.-4 A.sub.8 = -3.77695
.times. 10.sup.-5 A.sub.10 = 0 3rd surface K = 0.000 A.sub.4 =
-8.25212 .times. 10.sup.-3 A.sub.6 = 1.05654 .times. 10.sup.-3
A.sub.8 = -5.98956 .times. 10.sup.-5 A.sub.10 = 0 4th surface K =
0.000 A.sub.4 = -8.12513 .times. 10.sup.-3 A.sub.6 = 7.44821
.times. 10.sup.-4 A.sub.8 = -4.70205 .times. 10.sup.-5 A.sub.10 = 0
6th surface K = 0.000 A.sub.4 = -5.56006 .times. 10.sup.-4 A.sub.6
= 3.61032 .times. 10.sup.-5 A.sub.8 = -1.57815 .times. 10.sup.-5
A.sub.10 = 0 7th surface K = 0.000 A.sub.4 = 2.56154 .times.
10.sup.-3 A.sub.6 = -5.93015 .times. 10.sup.-4 A.sub.8 = 8.21499
.times. 10.sup.-5 A.sub.10 = 0 8th surface K = 0.000 A.sub.4 =
-1.61498 .times. 10.sup.-2 A.sub.6 = 2.62229 .times. 10.sup.-4
A.sub.8 = 1.11700 .times. 10.sup.-4 A.sub.10 = 0 9th surface K =
0.000 A.sub.4 = -1.33711 .times. 10.sup.-2 A.sub.6 = 1.83066
.times. 10.sup.-3 A.sub.8 = 1.80922 .times. 10.sup.-4 A.sub.10 = 0
Zooming Data (.infin.) WE ST TE f (mm) 5.700 7.600 10.500 F.sub.NO
2.84 3.24 3.86 2.omega. (.degree.) 62.48 47.32 34.74 d.sub.4 5.79
3.28 1.20 d.sub.9 3.55 4.78 6.67
Example 2
TABLE-US-00002 [0187] r.sub.1 = 742.482 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.88300 .nu..sub.d1 = 40.76 r.sub.2 = 5.785 (Aspheric)
d.sub.2 = 1.66 r.sub.3 = 7.599 (Aspheric) d.sub.3 = 1.88 n.sub.d2 =
4.84666 .nu..sub.d2 = 23.78 r.sub.4 = 16.421 (Aspheric) d.sub.4 =
(Variable) r.sub.5 = .infin. (Stop) d.sub.5 = 0.80 r.sub.6 = 4.194
(Aspheric) d.sub.6 = 3.18 n.sub.d3 = 1.49700 .nu..sub.d3 = 81.54
r.sub.7 = -20.581 (Aspheric) d.sub.7 = 0.00 r.sub.8 = 13.506
(Aspheric) d.sub.8 = 0.80 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.9 = 6.472 (Aspheric) d.sub.9 = (Variable) r.sub.10 = .infin.
d.sub.10 = 1.44 n.sub.d5 = 4.54771 .nu..sub.d5 = 62.84 r.sub.11 =
.infin. d.sub.11 = 0.80 r.sub.12 = .infin. d.sub.12 = 0.80 n.sub.d6
= 1.51633 .nu..sub.d6 = 64.14 r.sub.13 = .infin. d.sub.13 = 1.00
r.sub.14 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 0.000 A.sub.4 = 9.25825 .times. 10.sup.-4 A.sub.6 =
-2.08555 .times. 10.sup.-5 A.sub.8 = 1.29524 .times. 10.sup.-7
A.sub.10 = 0 2nd surface K = 0.000 A.sub.4 = -1.75234 .times.
10.sup.-4 A.sub.6 = 6.38980 .times. 10.sup.-5 A.sub.8 = -2.65816
.times. 10.sup.-6 A.sub.10 = 0 3rd surface K = 0.000 A.sub.4 =
-1.50510 .times. 10.sup.-3 A.sub.6 = 3.91584 .times. 10.sup.-5
A.sub.8 = -3.01945 .times. 10.sup.-7 A.sub.10 = 0 4th surface K =
0.000 A.sub.4 = -1.01332 .times. 10.sup.-3 A.sub.6 = 1.61802
.times. 10.sup.-5 A.sub.8 = 1.03000 .times. 10.sup.-7 A.sub.10 = 0
6th surface K = 0.000 A.sub.4 = -7.98420 .times. 10.sup.-4 A.sub.6
= -1.86068 .times. 10.sup.-5 A.sub.8 = -2.94687 .times. 10.sup.-6
A.sub.10 = 0 7th surface K = 0.000 A.sub.4 = 2.17134 .times.
10.sup.-3 A.sub.6 = -3.36530 .times. 10.sup.-4 A.sub.8 = 2.23456
.times. 10.sup.-5 A.sub.10 = 0 8th surface K = 0.000 A.sub.4 =
3.99355 .times. 10.sup.-3 A.sub.6 = -2.87967 .times. 10.sup.-4
A.sub.8 = 1.70044 .times. 10.sup.-5 A.sub.10 = 0 9th surface K =
0.000 A.sub.4 = 5.40085 .times. 10.sup.-3 A.sub.6 = -1.35135
.times. 10.sup.-5 A.sub.8 = 3.54182 .times. 10.sup.-5 A.sub.10 = 0
Zooming Data (.infin.) WE ST TE f (mm) 5.472 9.450 16.492 F.sub.NO
2.84 3.49 4.67 2.omega. (.degree.) 64.66 38.94 22.72 d.sub.4 19.39
9.00 2.90 d.sub.9 8.11 11.30 16.96
Example 3
TABLE-US-00003 [0188] r.sub.1 = -79.529 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.88300 .nu..sub.d1 = 40.76 r.sub.2 = 6.338 (Aspheric)
d.sub.2 = 2.02 r.sub.3 = 9.087 (Aspheric) d.sub.3 = 2.14 n.sub.d2 =
1.84666 .nu..sub.d2 = 23.78 r.sub.4 = 25.643 (Aspheric) d.sub.4 =
(Variable) r.sub.5 = .infin. (Stop) d.sub.5 = 0.80 r.sub.6 = 4.591
(Aspheric) d.sub.6 = 3.76 n.sub.d3 = 1.49700 .nu..sub.d3 = 81.54
r.sub.7 = -19.255 (Aspheric) d.sub.7 = 0.00 r.sub.8 = 13.328
(Aspheric) d.sub.8 = 0.80 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.9 = 6.340 (Aspheric) d.sub.9 = (Variable) r.sub.10 = .infin.
d.sub.10 = 1.44 n.sub.d5 = 1.54771 .nu..sub.d5 = 62.84 r.sub.11 =
.infin. d.sub.11 = 0.80 r.sub.12 = .infin. d.sub.12 = 0.80 n.sub.d6
= 1.51633 .nu..sub.d5 = 64.14 r.sub.13 = .infin. d.sub.13 = 1.00
r.sub.14 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 0.000 A.sub.4 = 6.90799 .times. 10.sup.-4 A.sub.6 =
-1.17782 .times. 10.sup.-5 A.sub.8 = 4.88182 .times. 10.sup.-8
A.sub.10 = 0 2nd surface K = 0.000 A.sub.4 = -4.06939 .times.
10.sup.-4 A.sub.6 = 4.52557 .times. 10.sup.-5 A.sub.8 = -1.51312
.times. 10.sup.-6 A.sub.10 = 0 3rd surface K = 0.000 A.sub.4 =
-1.03153 .times. 10.sup.-3 A.sub.6 = 2.22306 .times. 10.sup.-5
A.sub.8 = -2.57487 .times. 10.sup.-7 A.sub.10 = 0 4th surface K =
0.000 A.sub.4 = -5.56360 .times. 10.sup.-4 A.sub.6 = 4.49314
.times. 10.sup.-6 A.sub.8 = 1.08906 .times. 10.sup.-8 A.sub.10 = 0
6th surface K = 0.000 A.sub.4 = -5.80555 .times. 10.sup.-4 A.sub.6
= -3.39765 .times. 10.sup.-6 A.sub.8 = -2.44132 .times. 10.sup.-6
A.sub.10 = 0 7th surface K = 0.000 A.sub.4 = 2.25406 .times.
10.sup.-3 A.sub.6 = -2.80904 .times. 10.sup.-4 A.sub.8 = 1.27498
.times. 10.sup.-5 A.sub.10 = 0 8th surface K = 0.000 A.sub.4 =
2.85554 .times. 10.sup.-3 A.sub.6 = -2.15203 .times. 10.sup.-4
A.sub.8 = 8.69324 .times. 10.sup.-6 A.sub.10 = 0 9th surface K =
0.000 A.sub.4 = 3.48116 .times. 10.sup.-3 A.sub.6 = 3.63247 .times.
10.sup.-6 A.sub.8 = 1.69137 .times. 10.sup.-5 A.sub.10 = 0 Zooming
Data (.infin.) WE ST TE f (mm) 5.500 11.000 22.000 F.sub.NO 2.84
3.73 5.53 2.omega. (.degree.) 64.38 33.66 17.14 d.sub.4 23.03 8.67
1.49 d.sub.9 9.02 13.72 23.11
Example 4
TABLE-US-00004 [0189] r.sub.1 = -60.278 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.88300 .nu..sub.d1 = 40.76 r.sub.2 = 7.222 (Aspheric)
d.sub.2 = 2.07 r.sub.3 = 8.952 (Aspheric) d.sub.3 = 2.08 n.sub.d2 =
1.84666 .nu..sub.d2 = 23.78 r.sub.4 = 22.635 (Aspheric) d.sub.4 =
(Variable) r.sub.5 = .infin. (Stop) d.sub.5 = 0.80 r.sub.6 = 4.814
(Aspheric) d.sub.6 = 3.81 n.sub.d3 = 1.49700 .nu..sub.d3 = 81.54
r.sub.7 = -24.368 (Aspheric) d.sub.7 = 0.00 r.sub.8 = 12.210
(Aspheric) d.sub.8 = 0.80 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.9 = 6.177 (Aspheric) d.sub.9 = (Variable) r.sub.10 = .infin.
d.sub.10 = 1.44 n.sub.d5 = 1.54771 .nu..sub.d5 = 62.84 r.sub.11 =
.infin. d.sub.11 = 0.80 r.sub.12 = .infin. d.sub.12 = 0.80 n.sub.d6
= 1.51633 .nu..sub.d6 = 64.14 r.sub.13 = .infin. d.sub.13 = 1.00
r.sub.14 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 0.000 A.sub.4 = 6.00951 .times. 10.sup.-4 A.sub.6 =
-8.43631 .times. 10.sup.-6 A.sub.8 = 3.37449 .times. 10.sup.-8
A.sub.10 = 0 2nd surface K = 0.000 A.sub.4 = -3.72010 .times.
10.sup.-4 A.sub.6 = 2.79016 .times. 10.sup.-5 A.sub.8 = -6.20166
.times. 10.sup.-7 A.sub.10 = 0 3rd surface K = 0.000 A.sub.4 =
-1.09669 .times. 10.sup.-3 A.sub.6 = 1.28385 .times. 10.sup.-5
A.sub.8 = -4.91592 .times. 10.sup.-8 A.sub.10 = 0 4th surface K =
0.000 A.sub.4 = -6.10641 .times. 10.sup.-4 A.sub.6 = 3.03012
.times. 10.sup.-6 A.sub.8 = 3.35101 .times. 10.sup.-8 A.sub.10 = 0
6th surface K = 0.000 A.sub.4 = -3.63773 .times. 10.sup.-4 A.sub.6
= -1.22811 .times. 10.sup.-5 A.sub.8 = -8.74615 .times. 10.sup.-7
A.sub.10 = 0 7th surface K = 0.000 A.sub.4 = 1.68273 .times.
10.sup.-3 A.sub.6 = -1.42484 .times. 10.sup.-4 A.sub.8 = 6.05817
.times. 10.sup.-6 A.sub.10 = 0 8th surface K = 0.000 A.sub.4 =
1.58428 .times. 10.sup.-3 A.sub.6 = -8.00129 .times. 10.sup.-6
A.sub.8 = -1.87986 .times. 10.sup.-6 A.sub.10 = 0 9th surface K =
0.000 A.sub.4 = 2.15661 .times. 10.sup.-3 A.sub.6 = 1.52232 .times.
10.sup.-4 A.sub.8 = 2.48220 .times. 10.sup.-6 A.sub.10 = 0 Zooming
Data (.infin.) WE ST TE f (mm) 5.500 11.870 26.600 F.sub.NO 2.84
3.79 6.02 2.omega. (.degree.) 62.56 31.34 14.22 d.sub.4 29.63 10.40
1.20 d.sub.9 9.74 15.00 27.15
Example 5
TABLE-US-00005 [0190] r.sub.1 = 72.039 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.88300 .nu..sub.d1 = 40.76 r.sub.2 = 4.217 (Aspheric)
d.sub.2 = 1.62 r.sub.3 = 5.885 (Aspheric) d.sub.3 = 1.27 n.sub.d2 =
1.84666 .nu..sub.d2 = 23.78 r.sub.4 = 9.267 (Aspheric) d.sub.4 =
(Variable) r.sub.5 = .infin. (Stop) d.sub.5 = 0.80 r.sub.6 = 3.053
(Aspheric) d.sub.6 = 3.93 n.sub.d3 = 1.49700 .nu..sub.d3 = 81.54
r.sub.7 = -6.282 (Aspheric) d.sub.7 = 0.00 r.sub.8 = 6.618
(Aspheric) d.sub.8 = 0.80 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.9 = 3.348 (Aspheric) d.sub.9 = (Variable) r.sub.10 = .infin.
d.sub.10 = 1.44 n.sub.d5 = 1.54771 .nu..sub.d5 = 62.84 r.sub.11 =
.infin. d.sub.11 = 0.80 r.sub.12 = .infin. d.sub.12 = 0.80 n.sub.d6
= 1.51633 .nu..sub.d6 = 64.14 r.sub.13 = .infin. d.sub.13 = 1.00
r.sub.14 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 0.000 A.sub.4 = 3.17076 .times. 10.sup.-3 A.sub.6 =
-1.37514 .times. 10.sup.-4 A.sub.8 = 1.96035 .times. 10.sup.-6
A.sub.10 = 0 2nd surface K = 0.000 A.sub.4 = 3.08247 .times.
10.sup.-3 A.sub.6 = 3.63679 .times. 10.sup.-4 A.sub.8 = -3.34382
.times. 10.sup.-5 A.sub.10 = 0 3rd surface K = 0.000 A.sub.4 =
-1.89408 .times. 10.sup.-3 A.sub.6 = 2.05447 .times. 10.sup.-4
A.sub.8 = -6.40061 .times. 10.sup.-6 A.sub.10 = 0 4th surface K =
0.000 A.sub.4 = -2.03988 .times. 10.sup.-3 A.sub.6 = 1.30917
.times. 10.sup.-4 A.sub.8 = -2.56924 .times. 10.sup.-6 A.sub.10 = 0
6th surface K = 0.000 A.sub.4 = -1.61253 .times. 10.sup.-3 A.sub.6
= -7.47302 .times. 10.sup.-5 A.sub.8 = -2.30842 .times. 10.sup.-5
A.sub.10 = 0 7th surface K = 0.000 A.sub.4 = 3.13913 .times.
10.sup.-3 A.sub.6 = -1.53242 .times. 10.sup.-3 A.sub.8 = 1.98597
.times. 10.sup.-4 A.sub.10 = 0 8th surface K = 0.000 A.sub.4 =
-1.43433 .times. 10.sup.-2 A.sub.6 = -2.19219 .times. 10.sup.-3
A.sub.8 = 6.46815 .times. 10.sup.-5 A.sub.10 = 0 9th surface K =
0.000 A.sub.4 = -1.54578 .times. 10.sup.-2 A.sub.6 = -1.19883
.times. 10.sup.-3 A.sub.8 = 2.38275 .times. 10.sup.-4 A.sub.10 = 0
Zooming Data (.infin.) WE ST TE f (mm) 4.38 6.18 8.45 F.sub.NO 2.84
3.28 3.84 2.omega. (.degree.) 76.60 56.40 42.44 d.sub.4 6.59 3.46
1.42 d.sub.9 2.77 4.13 5.86
Example 6
TABLE-US-00006 [0191] r.sub.1 = -31.474 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.88300 .nu..sub.d1 = 40.76 r.sub.2 = 6.197 (Aspheric)
d.sub.2 = 2.48 r.sub.3 = 10.479 (Aspheric) d.sub.3 = 2.20 n.sub.d2
= 1.84666 .nu..sub.d2 = 23.78 r.sub.4 = 47.491 (Aspheric) d.sub.4 =
(Variable) r.sub.5 = .infin. (Stop) d.sub.5 = 0.80 r.sub.6 = 3.789
(Aspheric) d.sub.6 = 3.61 n.sub.d3 = 1.49700 .nu..sub.d3 = 81.54
r.sub.7 = -16.623 (Aspheric) d.sub.7 = 0.00 r.sub.8 = -39.726
(Aspheric) d.sub.8 = 0.80 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.9 = 14.332 (Aspheric) d.sub.9 = (Variable) r.sub.10 = .infin.
d.sub.10 = 1.44 n.sub.d5 = 1.54771 .nu..sub.d5 = 62.84 r.sub.11 =
.infin. d.sub.11 = 0.80 r.sub.12 = .infin. d.sub.12 = 0.80 n.sub.d6
= 1.51633 .nu..sub.d6 = 64.14 r.sub.13 = .infin. d.sub.13 = 1.00
r.sub.14 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 0.000 A.sub.4 = 9.59521 .times. 10.sup.-4 A.sub.6 =
-1.72098 .times. 10.sup.-5 A.sub.8 = 1.13583 .times. 10.sup.-7
A.sub.10 = 0 2nd surface K = 0.000 A.sub.4 = -3.60488 .times.
10.sup.-4 A.sub.6 = 3.77368 .times. 10.sup.-5 A.sub.8 = -1.07135
.times. 10.sup.-6 A.sub.10 = 0 3rd surface K = 0.000 A.sub.4 =
-1.01828 .times. 10.sup.-3 A.sub.6 = 1.27783 .times. 10.sup.-5
A.sub.8 = 1.61699 .times. 10.sup.-7 A.sub.10 = 0 4th surface K =
0.000 A.sub.4 = -5.67770 .times. 10.sup.-4 A.sub.6 = 1.51253
.times. 10.sup.-6 A.sub.8 = 1.26398 .times. 10.sup.-7 A.sub.10 = 0
6th surface K = 0.000 A.sub.4 = -8.01515 .times. 10.sup.-4 A.sub.6
= -2.76063 .times. 10.sup.-5 A.sub.8 = -3.86277 .times. 10.sup.-6
A.sub.10 = 0 7th surface K = 0.000 A.sub.4 = 9.05298 .times.
10.sup.-3 A.sub.6 = -1.86656 .times. 10.sup.-3 A.sub.8 = 1.48924
.times. 10.sup.-4 A.sub.10 = 0 8th surface K = 0.000 A.sub.4 =
9.67002 .times. 10.sup.-3 A.sub.6 = -1.17161 .times. 10.sup.-3
A.sub.8 = 7.64468 .times. 10.sup.-5 A.sub.10 = 0 9th surface K =
0.000 A.sub.4 = 7.85242 .times. 10.sup.-3 A.sub.6 = 1.15922 .times.
10.sup.-4 A.sub.8 = 3.78215 .times. 10.sup.-5 A.sub.10 = 0 Zooming
Data (.infin.) WE ST TE f (mm) 4.380 7.516 12.700 F.sub.NO 2.84
3.42 4.40 2.omega. (.degree.) 76.94 48.04 29.34 d.sub.4 19.85 8.42
1.91 d.sub.9 6.61 9.22 13.52
Example 7
TABLE-US-00007 [0192] r.sub.1 = -21.847 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.88300 .nu..sub.d1 = 40.76 r.sub.2 = 6.937 (Aspheric)
d.sub.2 = 2.47 r.sub.3 = 9.213 (Aspheric) d.sub.3 = 2.21 n.sub.d2 =
1.84666 .nu..sub.d2 = 23.78 r.sub.4 = 32.046 (Aspheric) d.sub.4 =
(Variable) r.sub.5 = .infin. (Stop) d.sub.5 = 0.80 r.sub.6 = 3.998
(Aspheric) d.sub.6 = 3.54 n.sub.d3 = 1.49700 .nu..sub.d3 = 81.54
r.sub.7 = -21.908 (Aspheric) d.sub.7 = 0.00 r.sub.8 = -33.149
(Aspheric) d.sub.8 = 0.80 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78
r.sub.9 = 17.323 (Aspheric) d.sub.9 = (Variable) r.sub.10 = .infin.
d.sub.10 = 1.44 n.sub.d5 = 1.54771 .nu..sub.d5 = 62.84 r.sub.11 =
.infin. d.sub.11 = 0.80 r.sub.12 = .infin. d.sub.12 = 0.80 n.sub.d6
= 1.51633 .nu..sub.d6 = 64.14 r.sub.13 = .infin. d.sub.13 = 1.00
r.sub.14 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 0.000 A.sub.4 = 9.33410 .times. 10.sup.-4 A.sub.6 =
-1.30751 .times. 10.sup.-5 A.sub.8 = 6.70483 .times. 10.sup.-8
A.sub.10 = 0 2nd surface K = 0.000 A.sub.4 = -6.18417 .times.
10.sup.-4 A.sub.6 = 4.10180 .times. 10.sup.-5 A.sub.8 = -7.84432
.times. 10.sup.-7 A.sub.10 = 0 3rd surface K = 0.000 A.sub.4 =
-1.01784 .times. 10.sup.-3 A.sub.6 = 4.66075 .times. 10.sup.-6
A.sub.8 = 1.15224 .times. 10.sup.-7 A.sub.10 = 0 4th surface K =
0.000 A.sub.4 = -3.78733 .times. 10.sup.-4 A.sub.6 = -7.08997
.times. 10.sup.-6 A.sub.8 = 1.63277 .times. 10.sup.-7 A.sub.10 = 0
6th surface K = 0.000 A.sub.4 = -8.04530 .times. 10.sup.-4 A.sub.6
= -3.34025 .times. 10.sup.-5 A.sub.8 = -6.46621 .times. 10.sup.-6
A.sub.10 = 0 7th surface K = 0.000 A.sub.4 = 2.52254 .times.
10.sup.-3 A.sub.6 = -4.58004 .times. 10.sup.-4 A.sub.8 = 3.15723
.times. 10.sup.-5 A.sub.10 = 0 8th surface K = 0.000 A.sub.4 =
7.40135 .times. 10.sup.-3 A.sub.6 = -3.03505 .times. 10.sup.-4
A.sub.8 = 1.41481 .times. 10.sup.-5 A.sub.10 = 0 9th surface K =
0.000 A.sub.4 = 8.67706 .times. 10.sup.-3 A.sub.6 = 1.94947 .times.
10.sup.-4 A.sub.8 = 2.90374 .times. 10.sup.-5 A.sub.10 = 0 Zooming
Data (.infin.) WE ST TE f (mm) 4.380 8.500 16.900 F.sub.NO 2.84
3.57 5.07 2.omega. (.degree.) 77.14 42.86 22.26 d.sub.4 25.20 9.37
1.00 d.sub.9 7.72 11.24 18.43
Example 8
TABLE-US-00008 [0193] r.sub.1 = 41.9739 d.sub.1 = 1.2000 n.sub.d1 =
1.77250 .nu..sub.d1 = 49.60 r.sub.2 = 11.1642 d.sub.2 = 2.9000
r.sub.3 = .infin. d.sub.3 = 6.5000 n.sub.d2 = 1.78590 .nu..sub.d2 =
44.20 r.sub.4 = .infin. (Reflecting d.sub.4 = 6.0000 n.sub.d3 =
1.78590 .nu..sub.d3 = 44.20 surface) r.sub.5 = .infin. d.sub.5 =
0.3971 r.sub.6 = 28.0000 d.sub.6 = 1.2000 n.sub.d4 = 1.74330
.nu..sub.d4 = 49.33 r.sub.7 = 11.3578 d.sub.7 = 0.3457 (Aspheric)
r.sub.8 = 9.4845 d.sub.8 = 1.7925 n.sub.d5 = 1.84666 .nu..sub.d5 =
23.78 r.sub.9 = 14.2959 d.sub.9 = (Variable) r.sub.10 = .infin.
(Stop) d.sub.10 = 1.0000 r.sub.11 = 47.8757 d.sub.11 = 1.9600
n.sub.d6 = 1.72916 .nu..sub.d6 = 54.68 r.sub.12 = -9.0806 d.sub.12
= 0.7000 n.sub.d7 = 1.72825 .nu..sub.d7 = 28.46 r.sub.13 = -25.4395
d.sub.13 = (Variable) r.sub.14 = 9.1761 d.sub.14 = 1.9500 n.sub.d8
= 1.74330 .nu..sub.d8 = 49.33 (Aspheric) r.sub.15 = 75.3616
d.sub.15 = 0.8461 r.sub.16 = 24.3002 d.sub.16 = 3.8969 n.sub.d9 =
1.74330 .nu..sub.d9 = 49.33 r.sub.17 = .infin. d.sub.17 = 1.0000
n.sub.d10 = 1.72825 .nu..sub.d10 = 28.46 r.sub.18 = 4.8249 d.sub.18
= (Variable) r.sub.19 = 49.5382 d.sub.19 = 2.7500 n.sub.d11 =
1.69350 .nu..sub.d11 = 53.20 r.sub.20 = -10.0407 d.sub.20 = 0.8269
(Aspheric) r.sub.21 = .infin. d.sub.21 = 1.4400 n.sub.d12 = 1.54771
.nu..sub.d12 = 62.84 r.sub.22 = .infin. d.sub.22 = 0.8000 r.sub.23
= .infin. d.sub.23 = 0.8000 n.sub.d13 = 1.51633 .nu..sub.d13 =
64.14 r.sub.24 = .infin. d.sub.24 = 1.0447 r.sub.25 = .infin.
(Image Plane) Aspherical Coefficients 7th surface K = 0 A.sub.4 =
2.2504 .times. 10.sup.-5 A.sub.6 = 2.6875 .times. 10.sup.-6 A.sub.8
= -1.2962 .times. 10.sup.-7 A.sub.10 = 2.8718 .times. 10.sup.-9
14th surface K = 0 A.sub.4 = -9.8664 .times. 10.sup.-5 A.sub.6 =
4.0400 .times. 10.sup.-6 A.sub.8 = -4.4986 .times. 10.sup.-7
A.sub.10 = 1.3851 .times. 10.sup.-8 20th surface K = 0 A.sub.4 =
5.3089 .times. 10.sup.-4 A.sub.6 = -1.6198 .times. 10.sup.-5
A.sub.8 = 4.4581 .times. 10.sup.-7 A.sub.10 = -4.9080 .times.
10.sup.-9 Zooming Data (.infin.) WE ST TE f (mm) 6.02622 9.31725
14.28897 F.sub.NO 2.7652 3.4888 4.5271 2.omega. (.degree.) 62.00
43.00 29.00 d.sub.9 14.24100 6.97804 2.00694 d.sub.13 2.10000
6.51339 5.34809 d.sub.18 2.46549 5.31403 11.45279
Example 9
TABLE-US-00009 [0194] r.sub.1 = 37.425 d.sub.1 = 1.20 n.sub.d1 =
1.80610 .nu..sub.d1 = 40.92 r.sub.2 = 4.340 (Aspheric) d.sub.2 =
2.33 r.sub.3 = 8.271 d.sub.3 = 1.62 n.sub.d2 = 1.84666 .nu..sub.d2
= 23.78 r.sub.4 = 16.244 d.sub.4 = (Variable) r.sub.5 = .infin.
(Stop) d.sub.5 = -0.69 r.sub.6 = 4.921 (Aspheric) d.sub.6 = 3.18
n.sub.d3 = 1.58313 .nu..sub.d3 = 59.38 r.sub.7 = 7.888 d.sub.7 =
1.19 n.sub.d4 = 1.84666 .nu..sub.d4 = 23.78 r.sub.8 = 4.000 d.sub.8
= 2.21 n.sub.d5 = 1.51633 .nu..sub.d5 = 64.14 r.sub.9 = -18.220
(Aspheric) d.sub.9 = (Variable) r.sub.10 = .infin. d.sub.10 = 1.40
n.sub.d6 = 1.51633 .nu..sub.d6 = 64.14 r.sub.11 = .infin. d.sub.11
= 1.23 r.sub.12 = .infin. (Image Plane) Aspherical Coefficients 2nd
surface K = -0.616 A.sub.4 = 4.19816 .times. 10.sup.-5 A.sub.6 =
3.00998 .times. 10.sup.-6 A.sub.8 = -5.10775 .times. 10.sup.-7
A.sub.10 = 1.25720 .times. 10.sup.-8 6th surface K = -1.054 A.sub.4
= 5.11035 .times. 10.sup.-4 A.sub.6 = 5.98520 .times. 10.sup.-5
A.sub.8 = -7.46930 .times. 10.sup.-6 A.sub.10 = 4.30043 .times.
10.sup.-7 9th surface K = -3.568 A.sub.4 = 1.01719 .times.
10.sup.-3 A.sub.6 = 2.98170 .times. 10.sup.-4 A.sub.8 = -5.10422
.times. 10.sup.-5 A.sub.10 = 5.07257 .times. 10.sup.-6 Zooming Data
(.infin.) WE ST TE f (mm) 5.950 10.090 17.100 F.sub.NO 3.05 3.88
5.30 2.omega. (.degree.) 64.44 39.64 23.82 d.sub.4 13.06 6.02 1.87
d.sub.9 8.41 12.17 18.56
Example 10
TABLE-US-00010 [0195] r.sub.1 = 24.168 d.sub.1 = 1.20 n.sub.d1 =
1.77250 .nu..sub.d1 = 49.60 r.sub.2 = 3.625 (Aspheric) d.sub.2 =
1.71 r.sub.3 = 5.714 d.sub.3 = 1.68 n.sub.d2 = 1.75520 .nu..sub.d2
= 27.51 r.sub.4 = 10.180 d.sub.4 = (Variable) r.sub.5 = .infin.
(Stop) d.sub.5 = -0.35 r.sub.6 = 3.233 (Aspheric) d.sub.6 = 1.43
n.sub.d3 = 1.58313 .nu..sub.d3 = 59.38 r.sub.7 = 6.623 d.sub.7 =
0.80 n.sub.d4 = 1.80809 .nu..sub.d4 = 22.76 r.sub.8 = 3.386 d.sub.8
= 0.44 r.sub.9 = 11.388 d.sub.9 = 1.55 n.sub.d5 = 1.61800
.nu..sub.d5 = 63.33 r.sub.10 = -6.894 d.sub.10 = (Variable)
r.sub.11 = .infin. d.sub.11 = 1.40 n.sub.d6 = 1.51633 .nu..sub.d6 =
64.14 r.sub.12 = .infin. d.sub.12 = 0.60 r.sub.13 = .infin.
d.sub.13 = 0.50 n.sub.d7 = 1.51633 .nu..sub.d7 = 64.14 r.sub.14 =
.infin. d.sub.14 = 0.20 r.sub.15 = .infin. (Image Plane) Aspherical
Coefficients 2nd surface K = -0.465 A.sub.4 = -3.25794 .times.
10.sup.-11 A.sub.6 = 3.11677 .times. 10.sup.-13 A.sub.8 = -8.29472
.times. 10.sup.-7 A.sub.10 = 0 6th surface K = -0.640 A.sub.4 =
-2.72851 .times. 10.sup.-7 A.sub.6 = 6.13668 .times. 10.sup.-6
A.sub.8 = 5.73050 .times. 10.sup.-6 A.sub.10 = 0 Zooming Data
(.infin.) WE ST TE f (mm) 5.943 8.190 11.468 F.sub.NO 3.70 4.23
5.00 2.omega. (.degree.) 64.98 48.56 35.26 d.sub.4 7.41 3.96 1.35
d.sub.10 7.75 9.51 12.06
Example 11
TABLE-US-00011 [0196] r.sub.1 = 12462.55 .times. 10.sup.3 d.sub.1 =
1.20 n.sub.d1 = 1.77250 .nu..sub.d1 = 49.60 (Aspheric) r.sub.2 =
5.496 (Aspheric) d.sub.2 = 2.11 r.sub.3 = 7.122 (Aspheric) d.sub.3
= 1.80 n.sub.d2 = 1.82114 .nu..sub.d2 = 24.06 r.sub.4 = 10.794
(Aspheric) d.sub.4 = (Variable) r.sub.5 = .infin. (Stop) d.sub.5 =
-0.80 r.sub.6 = 3.761 (Aspheric) d.sub.6 = 3.00 n.sub.d3 = 1.49700
.nu..sub.d3 = 81.54 r.sub.7 = -18.002 (Aspheric) d.sub.7 = 0.10
r.sub.8 = 31057.39 .times. 10.sup.4 d.sub.8 = 0.80 n.sub.d4 =
1.80809 .nu..sub.d4 = 22.76 (Aspheric) r.sub.9 = 13.522 (Aspheric)
d.sub.9 = (Variable) r.sub.10 = .infin. d.sub.10 = 1.40 n.sub.d5 =
1.51633 .nu..sub.d5 = 64.14 r.sub.11 = .infin. d.sub.11 = 1.21
r.sub.12 = .infin. (Image Plane) Aspherical Coefficients 1st
surface K = 155897576578.712 A.sub.4 = 8.38348 .times. 10.sup.-4
A.sub.6 = -7.53985 .times. 10.sup.-6 A.sub.8 = -7.27194 .times.
10.sup.-13 A.sub.10 = -3.30876 .times. 10.sup.-16 2nd surface K =
0.000 A.sub.4 = 8.09861 .times. 10.sup.-8 A.sub.6 = 5.42172 .times.
10.sup.-5 A.sub.8 = 1.55129 .times. 10.sup.-8 A.sub.10 = -1.43967
.times. 10.sup.-13 3rd surface K = -4.030 A.sub.4 = 7.11686 .times.
10.sup.-11 A.sub.6 = 1.34660 .times. 10.sup.-13 A.sub.8 = 5.65779
.times. 10.sup.-11 A.sub.10 = 6.30109 .times. 10.sup.-9 4th surface
K = -0.009 A.sub.4 = -1.08004 .times. 10.sup.-3 A.sub.6 = -6.22520
.times. 10.sup.-8 A.sub.8 = 1.29836 .times. 10.sup.-13 A.sub.10 =
-9.49582 .times. 10.sup.-15 6th surface K = -0.291 A.sub.4 =
5.61401 .times. 10.sup.-6 A.sub.6 = 9.69717 .times. 10.sup.-7
A.sub.8 = 3.44988 .times. 10.sup.-6 A.sub.10 = 6.10050 .times.
10.sup.-8 7th surface K = 0.000 A.sub.4 = 4.23632 .times. 10.sup.-3
A.sub.6 = -4.72010 .times. 10.sup.-4 A.sub.8 = 9.20080 .times.
10.sup.-6 A.sub.10 = 8.25389 .times. 10.sup.-7 8th surface K =
-9001283945.651 A.sub.4 = 6.72716 .times. 10.sup.-3 A.sub.6 =
-5.24190 .times. 10.sup.-4 A.sub.8 = 7.77385 .times. 10.sup.-6
A.sub.10 = -5.06707 .times. 10.sup.-7 9th surface K = 0.000 A.sub.4
= 7.65620 .times. 10.sup.-3 A.sub.6 = -2.71735 .times. 10.sup.-8
A.sub.8 = 2.11395 .times. 10.sup.-5 A.sub.10 = 3.97777 .times.
10.sup.-6 Zooming Data (.infin.) WE ST TE f (mm) 5.906 10.178
17.050 F.sub.NO 2.86 3.68 5.00 2.omega. (.degree.) 65.34 39.32
23.82 d.sub.4 12.76 5.72 1.80 d.sub.9 8.25 11.60 17.00
Example 12
TABLE-US-00012 [0197] r.sub.1 = 16.208 (Aspheric) d.sub.1 = 1.20
n.sub.d1 = 1.69350 .nu..sub.d1 = 53.21 r.sub.2 = 4.307 (Aspheric)
d.sub.2 = 3.00 r.sub.3 = 5.183 d.sub.3 = 1.05 n.sub.d2 = 1.78470
.nu..sub.d2 = 26.29 r.sub.4 = 5.749 d.sub.4 = (Variable) r.sub.5 =
.infin. (Stop) d.sub.5 = -0.30 r.sub.6 = 3.994 (Aspheric) d.sub.6 =
2.22 n.sub.d3 = 1.49700 .nu..sub.d3 = 81.54 r.sub.7 = -7.208
(Aspheric) d.sub.7 = 0.10 r.sub.8 = 3.928 d.sub.8 = 0.70 n.sub.d4 =
1.80809 .nu..sub.d4 = 22.76 r.sub.9 = 2.591 d.sub.9 = (Variable)
r.sub.10 = .infin. d.sub.10 = 1.40 n.sub.d5 = 1.51633 .nu..sub.d5 =
64.14 r.sub.11 = .infin. d.sub.11 = 1.14 r.sub.12 = .infin. (Image
Plane) Aspherical Coefficients 1st surface K = 4.649 A.sub.4 =
-5.99321 .times. 10.sup.-5 A.sub.6 = 8.63310 .times. 10.sup.-7
A.sub.8 = 8.17942 .times. 10.sup.-10 A.sub.10 = 0 2nd surface K =
0.002 A.sub.4 = -2.45506 .times. 10.sup.-6 A.sub.6 = -7.04344
.times. 10.sup.-6 A.sub.8 = -5.87327 .times. 10.sup.-7 A.sub.10 = 0
6th surface K = -0.869 A.sub.4 = -1.68712 .times. 10.sup.-3 A.sub.6
= 6.67467 .times. 10.sup.-5 A.sub.8 = -6.39445 .times. 10.sup.-5
A.sub.10 = 0 7th surface K = 3.594 A.sub.4 = 1.13704 .times.
10.sup.-3 A.sub.6 = -6.24541 .times. 10.sup.-6 A.sub.8 = -3.84390
.times. 10.sup.-5 A.sub.10 = 0 Zooming Data (.infin.) WE ST TE f
(mm) 5.908 8.174 11.533 F.sub.NO 3.67 4.20 5.00 2.omega. (.degree.)
64.88 47.88 34.44 d.sub.4 8.19 4.27 1.30 d.sub.9 6.49 7.92
10.10
[0198] FIGS. 13 to 24 are aberration diagrams indicative of
spherical aberrations, comae, distortions and chromatic aberrations
of magnification of Examples 1 to 12 upon focused on an infinite
object point. In these diagrams, (a) stand for aberrations at the
wide-angle end, (b) those in the intermediate state and (c) those
at the telephoto end.
[0199] The values concerning condition (1) in Examples 1 to 12 are
enumerated below.
TABLE-US-00013 Example 1 2 3 4 5 6 Wide-angle .alpha. 5.70 6.28
6.86 6.91 6.53 6.71 Wide-angle .beta. 6.59 10.65 11.56 12.28 5.81
9.15 Wide-angle .alpha./.beta. 0.86 0.59 0.59 0.56 1.12 0.73
Telephoto end .alpha. 5.70 6.28 6.86 6.91 6.53 6.71 Telephoto end
.beta. 9.71 19.50 25.65 29.69 8.90 16.06 Telephoto end
.alpha./.beta. 0.59 0.32 0.27 0.23 0.73 0.42 Example 7 8 9 10 11 12
Wide-angle .alpha. 6.64 4.76 6.62 4.87 4.60 4.72 Wide-angle .beta.
10.26 18.82 16.66 14.32 13.96 11.75 Wide-angle .alpha./.beta. 0.65
0.25 0.40 0.34 0.33 0.40 Telephoto end .alpha. 6.64 8.01 6.62 4.87
4.60 4.72 Telephoto end .beta. 20.97 27.81 26.81 18.63 22.71 15.36
Telephoto end .alpha./.beta. 0.32 0.29 0.25 0.26 0.20 0.31
[0200] The values of .phi..alpha., .phi..beta. (=.phi..beta.')
concerning conditions (2) and (4) in Examples 1 to 12 and the
values of .phi..beta./.phi..alpha. (=.phi..beta.'/.phi..alpha.) at
the wide-angle end are also tabulated below.
TABLE-US-00014 Example 1 2 3 4 5 6 .phi..alpha. 3.67 5.33 5.91 6.27
3.34 4.90 .phi..beta. 4.07 4.80 5.12 5.28 4.09 4.51
.phi..beta./.phi..alpha. at the wide-angle end 1.11 0.90 0.87 0.84
1.22 0.92 Example 7 8 9 10 11 12 .phi..alpha. 5.32 5.20 5.13 3.30
5.04 3.20 .phi..beta. 4.80 5.68 4.61 3.47 4.60 3.62
.phi..beta./.phi..alpha. at the wide-angle end 0.90 1.09 0.90 1.05
0.91 1.13
[0201] In each example, the second lens group G2 (Examples 1-7 and
9-12) or the fourth lens group G4 (Example 8) is provided on its
image side with a low-pass filter F or F' having a near-infrared
sharp cut coat on its entrance surface side. This near-infrared
sharp cut coat is designed to have a transmittance of at least 80%
at 600 nm wavelength and a transmittance of up to 10% at 700 nm
wavelength. More specifically, the near-infrared sharp cut coat has
a multilayer structure made up of such 27 layers as mentioned below
provided that the design wavelength is 780 nm.
TABLE-US-00015 Physical Thickness Substrate Material (nm) .lamda./4
1st layer Al.sub.2O.sub.3 58.96 0.50 2nd layer TiO.sub.2 84.19 1.00
3rd layer SiO.sub.2 134.14 1.00 4th layer TiO.sub.2 84.19 1.00 5th
layer SiO.sub.2 134.14 1.00 6th layer TiO.sub.2 84.19 1.00 7th
layer SiO.sub.2 134.14 1.00 8th layer TiO.sub.2 84.19 1.00 9th
layer SiO.sub.2 134.14 1.00 10th layer TiO.sub.2 84.19 1.00 11th
layer SiO.sub.2 134.14 1.00 12th layer TiO.sub.2 84.19 1.00 13th
layer SiO.sub.2 134.14 1.00 14th layer TiO.sub.2 84.19 1.00 15th
layer SiO.sub.2 178.41 1.33 16th layer TiO.sub.2 101.03 1.21 17th
layer SiO.sub.2 167.67 1.25 18th layer TiO.sub.2 96.82 1.15 19th
layer SiO.sub.2 147.55 1.05 20th layer TiO.sub.2 84.19 1.00 21st
layer SiO.sub.2 160.97 1.20 22nd layer TiO.sub.2 84.19 1.00 23rd
layer SiO.sub.2 154.26 1.15 24th layer TiO.sub.2 95.13 1.13 25th
layer SiO.sub.2 160.97 1.20 26th layer TiO.sub.2 99.34 1.18 27th
layer SiO.sub.2 87.19 0.65
[0202] Air
[0203] The aforesaid near-infrared sharp cut coat has such
transmittance characteristics as shown in FIG. 25.
[0204] The low-pass filter F is provided on its exit surface side
with a color filter or coat for reducing the transmission of colors
at such a short wavelength range as shown in FIG. 26, thereby
making the color reproducibility of an electronic image much
higher.
[0205] Preferably, that filter or coat should be designed such that
the ratio of the transmittance of 420 nm wavelength with respect to
the highest transmittance of a wavelength that is found in the
range of 400 nm to 700 nm is at least 15% and that the ratio of 400
nm wavelength with respect to the highest wavelength transmittance
is up to 6%.
[0206] It is thus possible to reduce a discernible difference
between the colors perceived by the human eyes and the colors of
the image to be picked up and reproduced. In other words, it is
possible to prevent degradation in images due to the fact that a
color of short wavelength less likely to be perceived through the
human sense of sight can be readily seen by the human eyes.
[0207] When the ratio of the 400 nm wavelength transmittance is
greater than 6%, the short wavelength region less likely to be
perceived by the human eyes would be reproduced with perceivable
wavelengths. Conversely, when the ratio of the 420 nm wavelength
transmittance is less than 15%, a wavelength range perceivable by
the human eyes is less likely to be reproduced, putting colors in
an ill-balanced state.
[0208] Such means for limiting wavelengths can be more effective
for imaging systems using a complementary colors mosaic filter.
[0209] In each of the aforesaid examples, coating is applied in
such a way that, as shown in FIG. 26, the transmittance for 400 nm
wavelength is 0%, the transmittance for 420 nm is 90%, and the
transmittance for 440 nm peaks or reaches 100%.
[0210] With the synergistic action of the aforesaid near-infrared
sharp cut coat and that coating, the transmittance for 400 nm is
set at 0%, the transmittance for 420 nm at 80%, the transmittance
for 600 nm at 82%, and the transmittance for 700 nm at 2% with the
transmittance for 450 nm wavelength peaking at 99%, thereby
ensuring more faithful color reproduction.
[0211] The low-pass filter F is made up of three different filter
elements stacked one upon another in the optical axis direction,
each filter element having crystal axes in directions where, upon
projected onto the image plane, the azimuth angle is horizontal
(=0.degree.) and +45.degree. therefrom. Three such filter elements
are mutually displaced by a .mu.m in the horizontal direction and
by SQRT(1/2).times.a in the .+-.45.degree. direction for the
purpose of moire control, wherein SQRT means a square root.
[0212] The image pickup plane I of a CCD is provided thereon with a
complementary colors mosaic filter wherein, as shown in FIG. 27,
color filter elements of four colors, cyan, magenta, yellow and
green are arranged in a mosaic fashion corresponding to image
pickup pixels. More specifically, these four different color filter
elements, used in almost equal numbers, are arranged in such a
mosaic fashion that neighboring pixels do not correspond to the
same type of color filter elements, thereby ensuring more faithful
color reproduction.
[0213] To be more specific, the complementary colors mosaic filter
is composed of at least four different color filter elements as
shown in FIG. 27, which should preferably have such characteristics
as given below.
[0214] Each green color filter element G has a spectral strength
peak at a wavelength G.sub.P,
[0215] each yellow filter element Y.sub.e has a spectral strength
peak at a wavelength Y.sub.P,
[0216] each cyan filter element C has a spectral strength peak at a
wavelength C.sub.P, and
[0217] each magenta filter element M has spectral strength peaks at
wavelengths M.sub.P1 and M.sub.P2, and these wavelengths satisfy
the following conditions.
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
[0218] To ensure higher color reproducibility, it is preferred that
the green, yellow and cyan filter elements have a strength of at
least 80% at 530 nm wavelength with respect to their respective
spectral strength peaks, and the magenta filter elements have a
strength of 10% to 50% at 530 nm wavelength with their spectral
strength peak.
[0219] One example of the wavelength characteristics in the
aforesaid respective examples is shown in FIG. 28. The green filter
element G has a spectral strength peak at 525 nm. The yellow filter
element Y.sub.e has a spectral strength peak at 555 nm. The cyan
filter element C has a spectral strength peak at 510 nm. The
magenta filter element M has peaks at 445 nm and 620 nm. At 530 nm,
the respective color filter elements have, with respect to their
respective spectral strength peaks, strengths of 99% for G, 95% for
Y.sub.e, 97% for C and 38% for M.
[0220] For such a complementary colors filter, such signal
processing as mentioned below is electrically carried out by means
of a controller (not shown) (or a controller used with digital
cameras).
For luminance signals,
Y=|G+M+Y.sub.e+C|.times.1/4
For chromatic signals,
R-Y=|(M+Y.sub.e)-(G+C)|
B-Y=|(M+C)-(G+Y.sub.e)|
Through this signal processing, the signals from the complementary
colors filter are converted into R (red), G (green) and B (blue)
signals.
[0221] Now for, it is noted that the aforesaid near-infrared sharp
cut coat may be located anywhere on the optical path, and that the
number of low-pass filters F may be either two as mentioned above
or one.
[0222] In the zoom lens used with the electronic imaging system
according to the invention, the aperture stop of fixed shape (fixed
stop) and the light quantity control filter or shutter are
provided. As already described, the fixed stop should preferably be
configured such that when 1.5.times.10.sup.3.times.a/1 mm<F
where F is the full-aperture F-number at the telephoto end and a is
the minimum pixel pitch in mm of the electronic image pickup
device, the length of the aperture stop in the vertical or
horizontal direction of the image pickup plane is longer than the
length of the aperture stop in the diagonal direction of the image
pickup plane.
[0223] By use of, for instance, any one of the configurations shown
in FIGS. 29(a), 29(b) and 29(c), the influence of diffraction can
be minimized. For photography where it is desired to minimize the
influence of diffraction in the horizontal direction in particular,
it is preferable to use an oblong aperture stop.
[0224] Alternatively, the fixed stop should preferably be
configured such that when 1.5.times.10.sup.3.times.a/1 mm>F, the
length of the aperture stop in the vertical or horizontal direction
of the image pickup plane is shorter than the length of the
aperture stop in the diagonal direction of the image pickup
plane.
[0225] By use of, for instance, any one of the configurations shown
in FIGS. 30(a), 30(b) and 30(c), the influence of geometrical
aberrations can be minimized. For photography where it is desired
to minimize the influence of geometrical aberrations in the
horizontal direction in particular, it is preferable to use an
oblong aperture stop.
[0226] Referring here to numerical data on zoom lenses, the spacing
between the fixed stop and the subsequent lens surface has often a
minus value due to the fact that the lens surface is positioned
with respect to the fixed stop position in the opposite direction
to the optical axis direction. In such cases, the fixed stop takes
a plane plate form. However, it is acceptable to use an optically
blacked lens surface having a circular aperture (see FIG. 34), a
funnel-form stop applied over the lens surface along the gradient
of the convex lens (see FIG. 31) or a stop formed by a lens holding
barrel.
[0227] For light quantity control, it is acceptable to use a
turret-form filter that, as shown in FIG. 32, comprises a turret
10'' having a plain or hollow aperture 1A'', an aperture 1B''
defined by an ND filter having a transmittance of 1/2, an aperture
1C'' defined by an ND filter having a transmittance of 1/4, an
aperture 1D'' defined by an ND filter having a transmittance of
1/8, etc.
[0228] For the light quantity control filter, it is also acceptable
to use a filter surface capable of performing light quantity
control in such a way as to reduce light quantity variations, for
instance, a filter in which, as shown in FIG. 33, the quantity of
light decreases concentrically toward its center in such a way that
for a dark subject, uniform transmittance is achieved while the
quantity of light at its center is preferentially ensured, and for
a bright subject alone, brightness variations are made up for.
[0229] Further, as schematically shown in FIG. 34, it is acceptable
to insert or de-insert a filter S2 in or from an optical path by
fluctuation (rocking or swaying movement). This in turn makes space
savings possible because there is some space after the second lens
group G2.
[0230] It is also acceptable to tilt the light quantity control
filter S2 with respect to the optical axis as schematically shown
in FIG. 35, so that ghosts due to light reflected at ND filters can
be reduced or eliminated. With the filter S2 having a fluctuating
structure, fast phototaking operation is achievable because the
angle of movement upon fluctuation can be set within an acute
range.
[0231] The light quantity control filter could be formed of two
polarizing filter elements of which the polarization directions are
varied for light quantity control. Instead of or in addition to the
filter, a shutter could be used. For that shutter, various shutters
represented by a focal plane shutter having a moving curtain
located in the vicinity of the image plane, a double-blade lens
shutter located in the optical path, a focal plane shutter and a
liquid crystal shutter could be used.
[0232] FIG. 36 is illustrative of one example of the shutter used
herein. FIGS. 36(a) and 36(b) are a rear and a front view of a
rotary focal plane shutter that is a sort of the focal plane
shutter. Reference numeral 15 is a shutter substrate that is to be
located just before the image plane or at any desired position in
the optical path. The substrate 15 is provided with an aperture 16
through which an effective light beam through an optical system is
transmitted. Numeral 17 is a rotary shutter curtain, and 18 a
rotary shaft of the rotary shutter curtain 17. The rotary shaft 18
rotates with respect to the substrate 15, and is integral with the
rotary shutter curtain 17. The rotary shaft 18 is engaged with
gears 19 and 20 on the surface of the substrate 15. The gears 19
and 20 are connected to a motor not shown.
[0233] As the motor not shown is driven, the rotary shutter curtain
17 is rotated around the rotary shaft 18 via the gears 19 and
20.
[0234] Having a substantially semi-circular shape, the rotary
shutter curtain 17 is rotated to open or close the aperture 16 in
the substrate 15 to perform a shutter role. The shutter speed is
then controlled by varying the speed of rotation of the rotary
shutter curtain 17.
[0235] FIGS. 37(a) to 37(d) are illustrative of how the rotary
shutter curtain 17 is rotated as viewed from the image plane side.
The rotary shutter curtain 17 is displaced in time order of (a),
(b), (c), (d) and (a).
[0236] By locating the aperture stop of fixed shape and the light
quantity control filter or shutter at different positions in the
zoom lens, it is thus possible to obtain an imaging system in
which, while high image quality is maintained with the influence of
diffraction minimized, the quantity of light is controlled by the
filter or shutter, and the length of the zoom lens can be cut down
as well.
[0237] The present electronic imaging system constructed as
described above may be applied to phototaking systems where object
images formed through zoom lenses are received at image pickup
devices such as CCDs or silver-halide films, inter alia, digital
cameras or video cameras as well as PCs and telephone sets that are
typical information processors, in particular, easy-to-carry
cellular phones. Given below are some such embodiments.
[0238] FIGS. 38, 39 and 40 are conceptual illustrations of a
phototaking optical system 41 for digital cameras, in which the
zoom lens of the invention is incorporated. FIG. 38 is a front
perspective view of the outside shape of a digital camera 40, and
FIG. 39 is a rear perspective view of the same. FIG. 40 is a
sectional view of the construction of the digital camera 40. In
this embodiment, the digital camera 40 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 45,
a flash 46, a liquid crystal monitor 47 and so on. As the shutter
45 mounted on the upper portion of the camera 40 is pressed down,
phototaking takes place through the phototaking optical system 41,
for instance, the zoom lens according to Example 1. An object image
formed by the phototaking optical system 41 is formed on the image
pickup plane of a CCD 49 via an optical low-pass filter F provided
with a near-infrared cut coat. An object image received at CCD 49
is shown as an electronic image on the liquid crystal monitor 47
via processing means 51, which monitor is mounted on the back of
the camera. This processing means 51 is connected with recording
means 52 in which the phototaken electronic image may be recorded.
It is here noted that the recording means 52 may be provided
separately from the processing means 51 or, alternatively, it may
be constructed in such a way that images are electronically
recorded and written therein by means of floppy discs, memory
cards, MOs or the like. This camera may also be constructed in the
form of a silver-halide camera using a silver-halide film in place
of CCD 49.
[0239] Moreover, a finder objective optical system 53 is located on
the finder optical path 44. An object image formed by the finder
objective optical system 53 is in turn formed on the field frame 57
of a Porro prism 55 that is an image-erecting member. In the rear
of the Porro prism 55 there is located an eyepiece optical system
59 for guiding an erected image into the eyeball E of an observer.
It is here noted that cover members 50 are provided on the entrance
sides of the phototaking optical system 41 and finder objective
optical system 53 as well as on the exit side of the eyepiece
optical system 59.
[0240] With the thus constructed digital camera 40, it is possible
to achieve high performance and cost reductions, because the
phototaking optical system 41 is constructed of a zoom lens having
a high zoom ratio at the wide-angle end with satisfactory
aberrations and a back focus large enough to receive a filter, etc.
therein.
[0241] In the embodiment of FIG. 40, plane-parallel plates are used
as the cover members 50; however, it is acceptable to use powered
lenses.
[0242] FIGS. 41, 42 and 43 are illustrative of a personal computer
that is one example of the information processor in which the zoom
lens of the invention is built as an objective optical system. FIG.
41 is a front perspective view of a personal computer 300 that is
in an uncovered state, FIG. 42 is a sectional view of a phototaking
optical system 303 in the personal computer 300, and FIG. 43 is a
side view of the state of FIG. 41. As shown in FIGS. 41, 42 and 43,
the personal computer 300 comprises a keyboard 301 via which an
operator enters information therein from outside, information
processing or recording means (not shown), a monitor 302 on which
the information is shown for the operator, and a phototaking
optical system 303 for taking an image of the operator and
surrounding images. For the monitor 302, use may be made of a
transmission type liquid crystal display device illuminated by
backlight (not shown) from the back surface, a reflection type
liquid crystal display device in which light from the front is
reflected to show images, or a CRT display device. While the
phototaking optical system 303 is shown as being built in the right
upper portion of the monitor 302, it may be located somewhere
around the monitor 302 or keyboard 301.
[0243] This phototaking optical system 303 comprises, on a
phototaking optical path 304, an objective lens 112 comprising the
zoom lens of the invention (roughly shown) and an image pickup
device chip 162 for receiving an image. These are built in the
personal computer 300.
[0244] Here an optical low-pass filter F is additionally applied
onto the image pickup device chip 162 to form an integral imaging
unit 160, which can be fitted into the rear end of the lens barrel
113 of the objective lens 112 in one-touch operation. Thus, the
assembly of the objective lens 112 and image pickup device chip 162
is facilitated because of no need of alignment or control of
surface-to-surface spacing. The lens barrel 113 is provided at its
end (not shown) with a cover glass 114 for protection of the
objective lens 112. It is here noted that driving mechanisms for
the zoom lens, etc. contained in the lens barrel 113 are not
shown.
[0245] An object image received at the image pickup device chip 162
is entered via a terminal 166 in the processing means of the
personal computer 300, and shown as an electronic image on the
monitor 302. As an example, an image 305 taken of the operator is
shown in FIG. 41. This image 305 may be shown on a personal
computer on the other end via suitable processing means and the
Internet or telephone line.
[0246] FIGS. 44(a), 44(b) and 44(c) are illustrative of a telephone
set that is one example of the information processor in which the
zoom lens of the invention is built in the form of a phototaking
optical system, especially a convenient-to-carry cellular phone.
FIG. 44(a) and FIG. 44(b) are a front and a side view of a cellular
phone 400, respectively, and FIG. 44(c) is a sectional view of a
phototaking optical system 405. As shown in FIGS. 44(a), 44(b) and
44(c), the cellular phone 400 comprises a microphone 401 for
entering the voice of an operator therein as information, a speaker
402 for producing the voice of the person on the other end, an
input dial 403 via which the operator enters information therein, a
monitor 404 for displaying an image taken of the operator or the
person on the other end and indicating information such as
telephone numbers, a phototaking optical system 405, an antenna 406
for transmitting and receiving communication waves, and processing
means (not shown) for processing image information, communication
information, input signals, etc. Here the monitor 404 is a liquid
crystal display device. It is noted that the components are not
necessarily arranged as shown. The phototaking optical system 405
comprises, on a phototaking optical path 407, an objective lens 112
comprising the zoom lens of the invention (roughly shown) and an
image pickup device chip 162 for receiving an object image. These
are built in the cellular phone 400.
[0247] Here an optical low-pass filter F is additionally applied
onto the image pickup device chip 162 to form an integral imaging
unit 160, which can be fitted into the rear end of the lens barrel
113 of the objective lens 112 in one-touch operation. Thus, the
assembly of the objective lens 112 and image pickup device chip 162
is facilitated because of no need of alignment or control of
surface-to-surface spacing. The lens barrel 113 is provided at its
end (not shown) with a cover glass 114 for protection of the
objective lens 112. It is here noted that driving mechanisms for
the zoom lens, etc. contained in the lens barrel 113 are not
shown.
[0248] An object image received at the image pickup device chip 162
is entered via a terminal 166 in processing means (not shown), so
that the object image can be displayed as an electronic image on
the monitor 404 and/or a monitor at the other end. The processing
means also include a signal processing function for converting
information about the object image received at the image pickup
device chip 162 into transmittable signals, thereby sending the
image to the person at the other end.
[0249] It is here understood that each of the embodiments mentioned
above could be modified in various fashions without any departure
from the scope of what is claimed.
[0250] As can be seen from the foregoing, the present invention can
provide a digital camera or other imaging system in which, while
high image quality is maintained with the influence of diffraction
minimized, the quantity of light is controlled by the filter or
shutter, and which enables the length of the zoom lens to be cut
down.
* * * * *