U.S. patent application number 09/176264 was filed with the patent office on 2001-10-18 for zoom lens.
Invention is credited to HAYAKAWA, SHINGO, MOMOKI, KAZUHIKO.
Application Number | 20010030809 09/176264 |
Document ID | / |
Family ID | 27465684 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010030809 |
Kind Code |
A1 |
HAYAKAWA, SHINGO ; et
al. |
October 18, 2001 |
ZOOM LENS
Abstract
A zoom lens is disclosed comprising, from front to rear, a first
lens unit of positive refractive power, a second lens unit of
negative refractive power, a third lens unit of positive refractive
power, a fourth lens unit of negative refractive power, a fifth
lens unit of positive refractive power and a sixth lens unit of
negative refractive power, wherein, during zooming from the
wide-angle end to the telephoto end, the air separations between
the i-th and (i+1)st lens units are made to vary properly and the
ratio of the focal length of the fourth lens unit to the longest
focal length of the entire system is made to have a proper value.
In particular, a zoom lens is disclosed wherein the second lens
unit is made to decenter to stabilize the image.
Inventors: |
HAYAKAWA, SHINGO;
(KANAGAWA-KEN, JP) ; MOMOKI, KAZUHIKO;
(KANAGAWA-KEN, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
27465684 |
Appl. No.: |
09/176264 |
Filed: |
October 20, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09176264 |
Oct 20, 1998 |
|
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08404870 |
Mar 15, 1995 |
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6124972 |
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Current U.S.
Class: |
359/557 |
Current CPC
Class: |
G02B 15/145113 20190801;
G02B 15/1461 20190801; G02B 15/173 20130101 |
Class at
Publication: |
359/557 |
International
Class: |
G02B 027/64 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 1994 |
JP |
HEI 06-074390 |
Jul 12, 1994 |
JP |
HEI 06-182813 |
Aug 24, 1994 |
JP |
HEI 06-222443 |
Nov 7, 1994 |
JP |
HEI 06-297866 |
Claims
What is claimed is:
1. A zoom lens comprising, from front to rear, a first lens unit of
positive refractive power, a second lens unit of negative
refractive power, a third lens unit of positive refractive power, a
fourth lens unit of negative refractive power, a fifth lens unit of
positive refractive power and a sixth lens unit of negative
refractive power, zooming being performed by varying the
separations between said lens units, and said zoom lens satisfying
the following condition: 0.3<.vertline.f4/fT.vert- line.<10.0
where f4 is the focal length of said fourth lens unit and fT is the
longest focal length of the entire system.
2. A zoom lens according to claim 1, satisfying the following
conditions: 0.1<.vertline.f2/fT.vertline.<0.18
0.12<.vertline.f6/fT.vertline- .<0.3 where f2 and f6 are the
focal lengths of said second lens unit and said sixth lens unit,
respectively.
3. A zoom lens according to claim 1 or 2, wherein at least one of
said second lens unit and said fourth lens unit remains stationary
during zooming.
4. A zoom lens according to claim 1 or 2, wherein said fourth lens
unit includes a negative lens of meniscus form convex toward an
image side.
5. A zoom lens according to claim 1, wherein letting the
separations between the i-th and (i+1 )st lens units for a
wide-angle end and a telephoto end be denoted by DiW and DiT,
respectively, the following conditions are satisfied: D1W<D1T
D2W>D2T D3W<D3T D4W>D4T D5W>D5T
6. A zoom lens comprising, from front to rear, a first lens unit of
positive refractive power, a second lens unit of negative
refractive power, a third lens unit of positive refractive power, a
fourth lens unit of negative refractive power, a fifth lens unit of
positive refractive power and a sixth lens unit of negative
refractive power, zooming being performed by varying the
separations between said lens units, and said zoom lens satisfying
the following condition: 0.3<ln Z.sub.2/ln Z<1 where in
represents natural logarithm, Z.sub.2 is a zoom ratio of said
second lens unit in zooming from a wide-angle end to a telephoto
end, and Z is a zoom ratio of the entire system.
7. A zoom lens according to claim 6, satisfying the following
condition: 0.5<{square root}{square root over (f1/.multidot.fW
fT )}<3.0 where f1 is the focal length of said first lens unit
and fW and fT are the shortest and longest focal lengths of the
entire system, respectively.
8. A zoom lens according to claim 6, wherein at least one of said
second, said fourth and said sixth lens units remains stationary
during zooming.
9. A zoom lens according to claim 6, wherein letting the separation
between the i-th and (i+1)st lens units for a wide-angle end and a
telephoto end be denoted by DiW and DiT, respectively, the
following conditions are satisfied: D1W<D1T D2W>D2T
D3W<D3T D4W<D4T D5W>D5T
10. A zoom lens having an image stabilizing function, comprising at
least one lens unit positioned on each of the object side and image
side of a lens unit which is stationary during zooming and arranged
to move axially during zooming, wherein said lens unit which is
stationary during zooming is made to move in directions
substantially perpendicular to an optical axis so as to correct
shaking of an image.
11. A zoom lens having an image stabilizing function, comprising,
from front to rear, a first lens unit of positive refractive power
axially movable for zooming, a second lens unit of negative
refractive power stationary during zooming, a rear lens unit
including at least one lens unit, whose overall refractive power is
positive and axially movable for zooming, wherein said second lens
unit is made to move in directions substantially perpendicular to
an optical axis so as to correct shaking of an image.
12. A zoom lens having an image stabilizing function according to
claim 10, satisfying the following condition:
0.15<.vertline.fa/{square root}{square root over
(fW.multidot.fT)}.vertline.<0.5 where fa is the focal length of
said lens unit which is stationary during zooming, and fW and fT
are the shortest and longest focal lengths of the entire system,
respectively.
13. A zoom lens having an image stabilizing function according to
claim 10, satisfying the following conditions:
0.20<.vertline.foW/frW.vertli- ne.<1.50
0.80<.vertline.foT/frT.vertline.<6.0 where foW and foT are
the overall focal lengths for a wide-angle end and a telephoto end
of those lens units which are positioned on the object side of said
stationary lens unit, respectively, and frW and frT are the overall
focal lengths for the wide-angle end and the telephoto end of said
stationary lens unit and those lens units which are positioned on
the object side of said stationary lens unit, respectively.
14. A zoom lens having an image stabilizing function, comprising,
from front to rear, a first lens unit of positive refractive power,
a second lens unit of negative refractive power, a third lens unit
of positive refractive power, a fourth lens unit of positive
refractive power and a fifth lens unit of negative refractive
power, said second lens unit being made stationary during zooming,
and zooming being performed by varying the separations between said
lens units, wherein said second lens unit is made to move in
directions substantially perpendicular to an optical axis so as to
correct shaking of an image.
15. A zoom lens having an image stabilizing function according to
claim 14, wherein, during zooming from a wide-angle end to a
telephoto end, letting the separations for the wide-angle end and
the telephoto end between the i-th and (i+1)st lens units be
denoted by DiW and DiT, respetively, said lens units are moved in
such relation as to satisfy the following conditions: D1W<D1T
D2W>D2T D4W>D4T
16. A zoom lens having an image stabilizing function, comprising,
from front to rear, a first lens unit of positive refractive power,
a second lens unit of negative refractive power, a third lens unit
of positive refractive power, a fourth lens unit of negative
refractive power, a fifth lens unit of positive refractive power
and a sixth lens unit of negative refractive power, said second
lens unit being stationary during zooming, and zooming being
performed by varying the separations between said lens units,
wherein said second lens unit is made to move in directions
substantially perpendicular to an optical axis so as to correct
shaking of an image.
17. A zoom lens having an image stabilizing function according to
claim 16, wherein, during zooming from a wide-angle end to a
telephoto end, letting the separations between the i-th and (i+1)st
lens units for the wide-angle end and the telephoto end be denoted
by DiW and DiT, respectively, said lens units are made to move in
such relation as to satisfy the following conditions: D1W<D1T
D2W>D2T D3W<D3T D5W>D5T
18. A zoom lens having an image stabilizing function according to
claim 14 or 16, satisfying the following condition:
0.15<.vertline.fa/{square root}{square root over
(FW.multidot.fT)}.vertline.<0.5 where fa is the focal length of
said second lens unit, and fW and fT are the shortest and longest
focal lengths of the entire system, respectively.
19. A zoom lens having an image stabilizing function, comprising,
from front to rear, a first lens unit of positive refractive power,
a second lens unit of negative refractive power and a rear lens
unit including at least one lens unit and having a positive overall
refractive power, zooming from a wide-angle end to a telephoto end
being performed by axially moving said first lens unit and at least
one lens unit in said rear lens unit toward an object side, and the
shortest focal length of the entire system being shorter than the
diagonal length of an image frame, wherein said second lens unit is
made to move in directions perpendicular to an optical axis so as
to correct shaking of an image occurring when said zoom lens
vibrates.
20. A zoom lens having an image stabilizing function according to
claim 19, satisfying the following condition:
0.5<.vertline.f.sub.q/f.sub.o-- e.sub.T).vertline.<1.2 where
f.sub.o is the focal length of said first lens unit, f.sub.q is the
focal length for the telephoto end of said rear lens unit, and
e.sub.T is the principal point interval between said first lens
unit and said second lens unit for the telephoto end.
21. A zoom lens having an image stabilizing function according to
claim 19, satisfying the following condition:
1.1<[P.sub.p/P.sub.q]<1.7 where P.sub.p and P.sub.q are the
Petzval sums of said second lens unit and said rear lens unit,
respectively.
22. A zoom lens having an image stabilizing function, comprising,
from front to rear, a first lens unit of positive refractive power,
a second lens unit of negative refractive power, a third lens unit
of positive refractive power and a fourth lens unit of positive
refractive power, zooming being performed by varying the
separations between said lens units, wherein said second lens unit
is made to move in directions perpendicular to an optical axis so
as to correct shaking of an image occurring when said zoom lens
vibrates.
23. A zoom lens having an image stabilizing function according to
claim 22, satisfying the following condition:
0.5<.vertline.f.sub.q/(f.sub.o- -e.sub.T).vertline.<1.2 where
f.sub.o is the focal length of said first lens unit, f.sub.q is the
overall refractive power of said third lens unit and said fourth
lens unit for a telephoto end, and e.sub.T is the principal point
interval between said first lens unit and said second lens unit for
the telephoto end.
24. A zoom lens having an image stabilizing function according to
claim 22, satisfying the following condition:
1.1<.vertline.P.sub.p/P.sub.q.- vertline.<1.7 where P.sub.p
is the Petzval sum of said second lens unit and P.sub.q is the
total sum of the Petzval sums of said third lens unit and said
fourth lens unit.
25. A zoom lens having an image stabilizing function according to
claim 19, satisfying the following condition:
0.15<.vertline.f.sub.p/(fw.mul-
tidot.fT).sup.1/2.vertline.<0.50 where f.sub.p is the focal
length of said second lens unit and fW and fT are the shortest and
longest focal lengths of the entire system, respectively.
26. A zoom lens having an image stabilizing function according to
claim 19, wherein said second lens unit is made stationary during
zooming.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to zoom lenses of the telephoto type
suited to 35 mm cameras, video cameras or electronic still cameras
and, more particularly, to zoom lenses having four to six lens
units in total, of which certain ones are movable for zooming, and
having as high a range as 4 or thereabout with maintenance of a
high optical performance throughout the zooming range, while still
permitting improvements of the compact form of the entire
system.
[0003] 2. Description of the Related Art
[0004] For the photographic cameras and video cameras, there have
been demanded zoom lenses of high range with high optical
performance. Of these, the telephoto type has been proposed in a
wide variety of multi-unit zoom lenses in which three or more lens
units are movable for zooming.
[0005] For example, a 3-unit zoom lens of plus-minus- plus power
arrangement in this order from the object side, a 4-unit zoom lens
of plus-minus-plus-plus power arrangement, another 4-unit zoom lens
of plus-minus-minus- plus power arrangement, a 5-unit zoom lens of
plus-minus- plus-minus-plus power arrangement, another 5-unit zoom
lens of plus-minus-plus-plus-minus power arrangement, and many
others have been proposed, wherein a plurality of lens units are
moved to effect zooming.
[0006] Since, in these 3-unit, 4-unit and 5-unit zoom lenses, two
or more lens units contribute to a variation of the focal length,
so that the requirements of minimizing the bulk and size of the
entire lens system and of obtaining a desired zoom ratio can be
fulfilled at once.
[0007] Still another proposal for using six lens units has been
made in Japanese Laid-Open Patent Application No. Hei 4-186212.
With this 6-unit zoom lens of plus-minus- plus-minus-plus-minus
power arrangement in this order from the object side, the zooming
range is increased to as high as 10.
[0008] In general, for the zoom lenses, it is desired not only to
improve the compact form of the entire lens system but also to
extend the zooming range (increase the zoom ratio). To achieve a
great increase of the zooming range, the number of those lens units
which contribute to the variation of the focal length may be
increased. In addition, the refractive power of every lens unit may
be increased to strengthen the zooming effect in some cases. In
other cases, the movement of each of those lens units which
contribute to the variation of the focal length may be
increased.
[0009] In the former case, however, to maintain good stability of
aberration correction throughout the zooming range, it becomes
necessary to increase the number of constituent lenses, giving rise
to a difficult problem of improving the compact form of the entire
lens system.
[0010] In the latter case, to allow full zooming movements, the air
separations have to be much increased. This leads to elongate the
physical length of the complete lens. Particularly in a case where
the lens units move in complicated relation, the mounting mechanism
for the movable lens units becomes very elaborate, giving rise to a
difficult problem of improving the compact form of the entire lens
system.
[0011] Meanwhile, there have been previous proposals for preventing
a photographed or picked-up image from shaking. Optical systems
having such a capability, or image stabilizing optical systems, are
disclosed in, for example, Japanese Laid-Open Patent Application
No. Sho 50-80147, Japanese Patent Publication No. Sho 56-21133 and
Japanese Laid-Open Patent Application No. Sho 61-223819.
[0012] In Japanese Laid-Open Patent Application No. Sho 50-80147, a
zoom lens has two afocal zooming sections, wherein letting the
angular magnifications of the first and second sections be denoted
by M1 and M2, respectively, these sections are made to move in such
relation that M.sub.1=1-1/M.sub.2 is kept and at the same time the
second zooming section is held in fixed spatial alignment with the
original line of sight axis. The shaking of the image is thus
corrected to achieve stabilization of the zoom lens against small
angle deviation thereof from a desired line of sight.
[0013] In Japanese Patent Publication No. Sho 56-21133, vibrations
of the optical instrument are sensed by a detector. In response to
its output signal, part of the optics deflects to a direction so as
to compensate for accidental displacement of the instrument, thus
achieving stabilization of an image in space.
[0014] In Japanese Laid-Open Patent application No. Sho 61-223819,
a photographic system has a variable angle prism of the refraction
type arranged at the frontmost position. As the housing containing
the photographic system vibrates, this prism varies its apex angle
to deflect the image. Thus, the image is stabilized in space for
shooting.
[0015] Besides these, there are Japanese Patent Publications Nos.
Sho 56-34847 and Sho 57-7414, in which an optical member is
arranged in part of the photographic system to be held in fixed
spatial alignment with the line of sight. As vibrations occur, this
optical member and its mating one generate a prism that deflects
image light rays. A stabilized image is thus obtained on the focal
plane.
[0016] Another available method is to utilize an acceleration
sensor to detect vibrations of the housing of the photographic
system. A lens unit constituting part of the photographic system is
made to rotate in the directions perpendicular to an optical axis
so that the image is stabilized against jiggles or oscillations at
the focal plane.
[0017] In general, for the type of photographic system in which one
lens unit is made to vibrate in such a way as to prevent the image
from shaking, the operating mechanism for image stabilization is
required to have capabilities that the tolerable shaking of the
image to correct is large enough, that the movement or rotation of
that lens unit (shiftable lens unit) is small relative to the
oscillation of the image, and that the driving means is small in
size and light in weight.
[0018] The shiftable lens unit, when decentering, produces
decentering coma, decentering astigmatism, decentering chromatic
aberrations and decentering curvature of field aberrations. If
these aberrations are large, the image is caused to blur, although
the shaking of the image is corrected. For example, if large
decentering distortion is produced, the image shift in the paraxial
zone becomes appreciably different from that in the marginal zone.
For this reason, if the paraxial zone alone is taken into
consideration in controlling the decentering of the shiftable lens
unit to correct the shaking of the image, it is in the marginal
zone that a similar phenomenon to the shaking of the image takes
place, causing the optical performance to lower objectionably.
[0019] In short, for the zoom lenses having the image stabilizing
function, it is required that when the shiftable lens unit is moved
in orthogonal directions to the optical axis to the decentered
position, the amount of decentering aberrations produced is small
so the lowering of the optical performance is little and that the
required amount of movement of the shiftable lens unit for
correcting the equivalent shaking of the image is small, in other
words, the so-called decenter sensitivity (ratio of the corrected
amount, .DELTA.x, of shaking of the image to the unity of amount of
movement .DELTA.H, or .DELTA.x/.DELTA.H) is large.
[0020] According to the prior art, however, the image stabilizing
optical systems of the type using an optical member as arranged,
regardless of vibrations, to be held in fixed spatial alignment
with the line of sight, are not suited to be used in instruments of
small size and light weight, because this optical member is
difficult to operatively support-and because such optical systems
are difficult to realize in compact form. Another type of image
stabilizing optical system using a variable angular prism as
arranged in the frontmost position, though having a merit that,
when correcting the shaking, all decentering aberrations except
chromatic ones are produced to almost nothing, has problems that
the driving members become large in size and that the decentering
chromatic aberrations produced from the prism are difficult to
correct with ease.
[0021] Yet another type of image stabilizing optical systems using
one lens unit of the photographic optical system for decentering
purposes is considered to be amenable to the technique of
minimizing the size of the instrument by proper selection and
arrangement of the decentering lens unit. However, there is a
difficult problem of simultaneously fulfilling the requirements of
well correcting all the aberrations produced by decentering,
namely, decentering coma, decentering astigmatism and decentering
curvature of field and of realizing reflection of the sufficiently
small amount of decentering movement to a sufficiently great effect
of stabilizing the image.
SUMMARY OF THE INVENTION
[0022] The present invention makes up a zoom lens from six lens
units of specific refractive powers in total and sets forth proper
rules for the refractive powers of all the lens units and for the
relation in which the lens units move to effect zooming. Based on
these rules, the number of constituent lenses is reduced to insure
that the physical length of the complete lens is shortened in such
a manner that a high optical performance is maintained over the
entire zooming range. It is, therefore, an object of the invention
to provide a zoom lens of the telephoto type having a range of
about 4 with the image aberrations improved.
[0023] Another object of the invention is to provide a zoom lens
having an image stabilizing function and good optical performance.
To this end, the zoom lens of the character described above is used
as the base. In application to this zoom lens, the method of
correcting shaking of the image is by moving part of the zoom lens,
or the shiftable lens unit in directions perpendicular to an
optical axis. To this purpose, as the shiftable lens unit, a one of
small size and light weight is selected to use. In addition, its
small decentering movement is reflected to correct large amplitude
of shaking of the image. Furthermore, as the shiftable lens unit
moves to parallel decenter, any of the decentering aberrations
described before is produced to a smaller amount than was
heretofore common.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIGS. 1(A), 1(B) and 1 (C) are lens block diagrams of a
numerical example 1 of the invention.
[0025] FIGS. 2(A), 2(B) and 2(C) are lens block diagrams of a
numerical example 2 of the invention.
[0026] FIGS. 3(A), 3(B) and 3(C) are lens block diagrams of a
numerical example 3 of the invention.
[0027] FIGS. 4(A), 4(B) and 4(C) are graphic representations of the
various aberrations of the numerical example 1 of the
invention.
[0028] FIGS. 5(A), 5(B) and 5(C) are graphic representations of the
various aberrations of the numerical example 2 of the
invention.
[0029] FIGS. 6(A), 6(B) and 6(C) are graphic representations of the
various aberrations of the numerical example 3 of the
invention.
[0030] FIGS. 7(A), 7(B) and 7(C) are lens block diagrams of a
numerical example 4 of the invention.
[0031] FIGS. 8(A), 8(B) and 8(C) are lens block diagrams of a
numerical example 5 of the invention.
[0032] FIGS. 9(A), 9(B) and 9(C) are lens block diagrams of a
numerical example 6 of the invention.
[0033] FIGS. 10(A), 10(B) and 10(C) are lens block diagrams of a
numerical example 7 of the invention.
[0034] FIGS. 11(A), 11(B) and 11(C) are graphic representations of
the various aberrations of the numerical example 4 of the
invention.
[0035] FIGS. 12(A), 12(B) and 12(C) are graphic representations of
the various aberrations of the numerical example 5 of the
invention.
[0036] FIGS. 13(A), 13(B) and 13(C) are graphic representations of
the various aberrations of the numerical example 6 of the
invention.
[0037] FIGS. 14(A), 14(B) and 14(C) are graphic representations of
the various aberrations of the numerical example 7 of the
invention.
[0038] FIG. 15 is a schematic diagram of the paraxial refractive
power arrangements of a numerical example 8 of a zoom lens of the
invention.
[0039] FIGS. 16(A), 16(B) and 16(C) are lens block diagrams of the
numerical example 8 of the invention.
[0040] FIG. 17 is a schematic diagram of the paraxial refractive
power arrangements of a numerical example 9 of a zoom lens of the
invention.
[0041] FIGS. 18(A), 18(B) and 18(C) are lens block diagrams of the
numerical example 9 of the invention.
[0042] FIGS. 19(A) and 19(B) are graphic representations of the
aberrations of the numerical example 8 of the invention in the
wide-angle end with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0043] FIGS. 20(A) and 20(B) are graphic representations of the
aberrations of the numerical example 8 of the invention in a middle
position with an image respectively in the reference state and in a
corrected state from the vibration of 1 degree.
[0044] FIGS. 21(A) and 21(B) are graphic representations of the
aberrations of the numerical example 8 of the invention in the
telephoto end with an image respectively in the reference state and
in a corrected state from the vibration of 1 degree.
[0045] FIGS. 22(A) and 22(B) are graphic representations of the
aberrations of the numerical example 9 of the invention in the
wide-angle end with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0046] FIGS. 23(A) and 23(B) are graphic representations of the
aberrations of the numerical example 9 of the invention in a middle
position with an image respectively in the reference state and in a
corrected state from the vibration of 1 degree.
[0047] FIGS. 24(A) and 24(B) are graphic representations of the
aberrations of the numerical example 9 of the invention in the
telephoto end with an image respectively in the reference state and
in a corrected state from the vibration of 1 degree.
[0048] FIG. 25 is a diagram to explain the correction of
decentering aberrations according to the invention.
[0049] FIGS. 26(A) and 26(B) are diagrams to explain the correction
of decentering aberrations according to the invention.
[0050] FIGS. 27(A), 27(B) and 27(C) are lens block diagrams of a
numerical example 10 of the invention.
[0051] FIGS. 28(A), 28(B) and 28(C) are lens block diagrams of a
numerical example 11 of the invention.
[0052] FIGS. 29(A), 29(B) and 29(C) are lens block diagrams of a
numerical example 12 of the invention.
[0053] FIGS. 30(A) and 30(B) are graphic representations of the
aberrations of the numerical example 10 of the invention in the
wide-angle end with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0054] FIGS. 31(A) and 31(B) are graphic representations of the
aberrations of the numerical example 10 of the invention in a
middle position with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0055] FIGS. 32(A) and 32(B) are graphic representations of the
aberrations of the numerical example 10 of the invention in the
telephoto end with an image respectively in the reference state and
in a corrected state from the vibration of 1 degree.
[0056] FIGS. 33(A) and 33(B) are graphic representations of the
aberrations of the numerical example 11 of the invention in the
wide-angle end with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0057] FIGS. 34(A) and 34(B) are graphic representations of the
aberrations of the numerical example 11 of the invention in a
middle position with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0058] FIGS. 35(A) and 35(B) are graphic representations of the
aberrations of the numerical example 11 of the invention in the
telephoto end with an image respectively -in the reference state
and in a corrected state from the vibration of 1 degree.
[0059] FIGS. 36(A) and 36(B) are graphic representations of the
aberrations of the numerical example 12 of the invention in the
wide-angle end with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0060] FIGS. 37(A) and 37(B) are graphic representations of the
aberrations of the numerical example 12 of the invention in a
middle position with an image respectively in the reference state
and in a corrected state from the vibration of 1 degree.
[0061] FIGS. 38(A) and 38(B) are graphic representations of the
aberrations of the numerical example 12 of the invention in the
telephoto end with an image respectively in the reference state and
in a corrected state from the vibration of 1 degree.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0062] Numerical examples 1 to 3 of zoom lenses of the invention
are shown in the longitudinal section views of FIGS. 1(A), 1(B) and
1(C) through FIGS. 3(A), 3(B) and 3(C), respectively. The
aberrations of the zoom lenses of the numerical examples 1 to 3 are
shown in FIGS. 4(A), 4(B) and 4(C) through FIGS. 6(A), 6(B) and
6(C). Of the section views, the ones of the numbers with suffix (A)
are in the wide-angle end, the ones of the numbers with suffix (B)
in a middle position and the ones of the numbers with suffix (C) in
the telephoto end.
[0063] Referring to these figures, the zoom lens comprises, from
front to rear, a first lens unit L1 of positive refractive power, a
second lens unit L2 of negative refractive power, a third lens unit
L3 of positive refractive power, a fourth lens unit L4 of negative
refractive power, a fifth lens unit L5 of positive refractive power
and a sixth lens unit L6 of negative refractive power. SP stands
for a stop and IP for an image plane. The arrows indicate the loci
of motion of the lens units when zooming from the wide-angle end to
the telephoto end.
[0064] In the present embodiment, the lens units L1 to L6 are made
selectively movable for zooming, wherein the selection is specified
differently from item to item. For every one of these zoom lenses,
as zooming goes from the wide-angle end to the telephoto end, the
selected ones of the lens units move axially in such relation that
the separation between the first and second lens units increases,
the separation between the second and third lens units decreases,
the separation between the third and fourth lens units increases,
the separation between the fourth and fifth lens units decreases
and the separation between the fifth and sixth lens units
decreases.
[0065] In other words, letting the separations between the i-th and
(i+1)st lens units for the wide-angle end and the telephoto end be
denoted by DiW and DiT, respectively, the lens units are made to
move in such relation as to satisfy the following conditions:
[0066] D1W<D1T
[0067] D2W>D2T
[0068] D3W<D3T
[0069] D4W>D4T
[0070] D5W>D5T
[0071] An additional condition to satisfy is:
0.3<.vertline.f4/fT.vertline.<10.0 (1)
[0072] where f4 is the focal length of the fourth lens unit and fT
is the longest focal length of the entire system. When these
conditions are satisfied, the effect of varying the focal length is
shared in good balance by all the lens units, thereby making it
easy to extend the zooming range while still maintaining a
shortening of the total length of the entire system to be achieved.
Incidentally, the stop SP is made to move in unison with the third
lens unit.
[0073] In the zoom lens of the invention, for the wide- angle end,
the first and second lens unit are positioned so closely that their
combined refractive power becomes negative. The third and fourth
lens units are also closely positioned. Further, the third lens
unit and those that follow have their combined refractive power
made positive. With these, the entire lens system takes the
retrofocus type.
[0074] For the telephoto end, the second and third lens units are
positioned so closely that their combined refractive power becomes
negative. The fourth and fifth lens units and also the sixth lens
unit are positioned close to each other so that their combined
refractive power becomes negative or weakly positive. Further, the
stop is positioned near the third lens unit.
[0075] As the configuration of the lens units is made to vary in
such a way, it is in the wide-angle end that, although the
refractive power arrangement is made nearly of the retrofocus type,
the rearmost or sixth lens unit is permitted to be a negative lens
unit, thereby well correcting asymmetric aberrations such as coma.
With the same lens configuration, when in the telephoto end, the
refractive power arrangement becomes the telephoto type. The lens
system thus takes a compact form, while still permitting all
aberrations to be corrected well.
[0076] In addition, the refractive power of the fourth lens unit is
specified by the condition (1) to minimize the variation of
aberrations with zooming. The inequalities of condition (1) give a
range for the ratio of the focal length of the fourth lens unit to
the longest focal length of the entire system and have an aim
chiefly to define a refractive power arrangement that assures
maintenance of good stability of aberration correction throughout
the zooming range.
[0077] When the lower limit of the condition (1) is exceeded, as
this means that the absolute value of the focal length of the
fourth lens unit is too small as compared with the focal length for
the telephoto end of the entire system, it becomes necessary to
make relatively large the absolute value of the focal length of the
sixth lens unit. At this time, particularly in the wide-angle end,
the symmetry of the refractive power arrangement is worsened. So,
it becomes difficult to correct coma and other asymmetric
aberrations. Conversely when the upper limit of the condition (1)
is exceeded, as this means that the absolute value of the focal
length of the fourth lens unit is too large as compared with the
longest focal length of the entire system, it becomes difficult to
correct the variation of spherical aberration with zooming, since
this correction is done mainly by the fourth lens unit.
[0078] For the zoom lens of the invention, use is made of the six
lens units whose refractive powers are specified in sign as
described above in combination with the variations of the air
separations with zooming from the wide-angle end to the telephoto
end specified as described above. Further, the refractive power
arranged is made to satisfy the condition (1) described above.
Thus, all aberrations are corrected well, so that high optical
performance is maintained stable over the entire zooming range.
[0079] To further improve the variation of aberrations with
zooming, and to obtain a high image quality over the entire area of
the image frame, the invention sets forth the following additional
conditions:
0.1<.vertline.f2/fT.vertline.<0.18 (2)
0.12<.vertline.f6/fT.vertline.<0.3 (3)
[0080] where f2 and f6 are the focal lengths of the second and
sixth lens units, respectively.
[0081] The inequalities of condition (2) are concerned with the
ratio of the focal length of the second lens unit which has the
negative refractive power to the longest focal length of the entire
system, and the inequalities of condition (3) are concerned with
the ratio of the focal length of the sixth lens unit which has the
negative refractive power to the longest focal length of the entire
system.
[0082] The conditions (2) and (3) are combined with the condition
(1) described before to individually specify the focal lengths of
the negative lens units distributed over the entire system. This
combination represents the refractive power arrangement for the
zoom lens that can achieve the object of the invention.
[0083] When the lower limit of the condition (2) is exceeded, as
this means that the absolute value of the second lens unit is too
small, it becomes difficult mainly in the telephoto end to correct
coma and astigmatism. Conversely when the upper limit is exceeded,
as this means that the absolute value of the foal length of the
second lens unit is too large, the zooming movement of the first
lens unit must be increased. So, the physical length of the
complete lens increases objectionably.
[0084] When the lower limit of the condition (3) is exceeded, as
this means that the absolute value of the sixth lens unit is too
small, distortion of the pincushion type increases mainly in the
telephoto end. When the absolute value of the focal length of the
sixth lens unit is too large as exceeding the upper limit, it is in
the general case that the total length of the complete lens
increases objectionably.
[0085] The foregoing has been described in connection with the
demerits resulting from the departure of the focal lengths of the
lens units from the ranges of the conditions (2) and (3). However,
virtually, the above- described factors are related to one another
complicatedly. After the condition (1) is satisfied, when the
conditions (2) and (3) are satisfied, it becomes easy to correct
various aberrations well in such a manner that the zoom ratio is
kept high enough to 4 or thereabout and the compact form is
maintained.
[0086] In the present invention, at least one of the second and
fourth lens units may be made stationary during zooming. If so,
regardless of the use of the 6-unit type, the structure of the lens
barrel can be simplified. (In the numerical examples 1 and 2, the
second and fourth lens units remain stationary. In the numerical
example 3, the second lens unit remains stationary.) Also, in the
present invention, the fourth lens unit is constructed with a
single negative lens of meniscus form convex toward the image side
under the control of the condition (1). By this, variation of
mainly spherical aberration with zooming is corrected well.
[0087] Besides these, in the invention, the third lens unit is
constructed with a positive lens and a cemented lens of a positive
lens and a negative lens to form two groups with three members. The
fifth lens unit is constructed with a cemented lens of a positive
lens and a negative lens and a positive lens to form two groups
with three members, or with a positive lens and a negative lens to
form two groups with two members. The sixth lens unit is
constructed with a negative lens and a cemented lens of a positive
lens and a negative lens to form two groups with three members, or
with a cemented lens of a negative lens and a positive lens to form
one group with two members, or with a negative lens and a positive
lens to form two groups with two members. With these, the variation
of aberrations with zooming is corrected for a high optical
performance throughout the entire zooming range.
[0088] It should be noted that, as will be described more fully
later, the lens system is amenable to the image stabilizing
capability by decentering the second lens unit.
[0089] Next, numerical examples 1 to 3 of the invention are shown.
In the numerical data for the examples 1 to 3, Ri is the radius of
curvature of the i-th lens surface, when counted from the object
side, Di is the i-th axial lens thickness or air separation, when
counted from the object side and Ni and vi are respectively the
refractive index and Abbe number of the glass of the i-th lens
element, when counted from the object side. The values of the
factors in the above-described conditions for the numerical
examples are listed in Table-1.
NUMERICAL EXAMPLE 1
[0090] Focal Length: 76.51-292.00
[0091] F-Number: 4.00-5.86
1 R1 = 103.34 D1 = 2.8 N1 = 1.80518 .nu.1 = 25.4 R2 = 65.53 D2 =
6.6 N2 = 1.51633 .nu.2 = 64.2 R3 = 1941.34 D3 = 0.2 R4 = 212.98 D4
= 4.2 N3 = 1.48749 .nu.3 = 70.2
[0092]
2 R 5 = -305.81 D 5 = Variable R 6 = -115.87 D 6 = 1.5 N 4 =
1.77250 .nu.4 = 49.6 R 7 = 131.18 D 7 = 2.8 R 8 = -57.65 D 8 = 1.5
N 5 = 1.60311 .nu.5 = 60.7 R 9 = 60.38 D 9 = 3.4 N 6 = 1.84666
.nu.6 = 23.8 R10 = 313.25 D10 = Variable R11 = 366.28 D11 = 3.4 N 7
= 1.48749 .nu.7 = 70.2 R12 = 89.07 D12 = 0.2 R13 = 50.08 D13 = 5.2
N 8 = 1.60311 .nu.8 = 60.7 R14 = -90.47 D14 = 1.5 N 9 = 1.33400
.nu.9 = 37.2 R15 = -5450.60 D15 = 2.0 R16 = (Stop) D16 = Variable
R17 = -85.14 D17 = 2.5 N10 = 1.51633 .nu.10 = 64.2 R18 = -114.60
D18 = Variable R19 = 124.60 D19 = 4.4 N11 = 1.60311 .nu.11 = 60.7
R20 = -38.67 D20 = 1.5 N12 = 1.80518 .nu.12 = 25.4 R21 = -181.93
D21 = 0.2 R22 = 56.62 D22 = 3.4 N13 = 1.51633 .nu.13 = 64.2 R23 =
-206.31 D23 = Variable R24 = -51.93 D24 = 1.5 N14 = 1.77250 .nu.14
= 49.6 R25 = 71.28 D25 = 1.4 R26 = 641.53 D26 = 4.0 N15 = 1.80518
.nu.15 = 25.4 R27 = -38.69 D27 = 1.5 N16 = 1.69680 .nu.16 = 55.5
R28 = -907.33
[0093]
3 Variable Focal Length Separations 76.51 135.00 292.00 D5 4.00
28.11 59.00 D10 36.01 21.37 2.49 D16 3.00 17.63 36.52 D18 30.24
16.59 15.51 D23 16.09 12.99 2.99
NUMERICAL EXAMPLE 2
[0094] Focal Length: 76.53-291.99
[0095] F-Number: 4.05-5.78
4 R 1 = 117.46 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 70.46 D 2
= 6.1 N2 = 1.51633 .nu.2 = 64.2 R 3 = 896.98 D 3 = 0.2 R 4 = 110.38
D 4 = 5.4 N 3 = 1.48749 .nu.3 = 70.2 R 5 = -444.29 D 5 = Variable R
6 = -103.08 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 = 79.32 D 7 =
2.8 R 8 = 70.54 D 8 = 1.5 N 5 = 1.60311 .nu.5 = 60.7 R 9 = 43.52 D
9 = 3.6 N 6 = 1.84666 .nu.6 = 23.8 R10 = 188.82 D10 = Variable R11
= 70.72 D11 = 4.1 N 7 = 1.60311 .nu.7 = 60.7 R12 = 95.89 D12 = 0.2
R13 = 69.47 D13 = 4.6 N 8 = 1.60311 .nu.8 = 60.7 R14 = 58.59 D14 =
1.5 N 9 = 1.83400 .nu.9 = 37.2 R15 = 275.47 D15 = 2.0 R16 = (Stop)
D16 = Variable R17 = 56.86 D17 = 2.5 N10 = 1.51633 .nu.10 = 64.2
R18 = -84.28 D18 = Variable R19 = 137.95 D19 = 5.4 N11 = 1.60311
.nu.11 = 60.7 R20 = -33.51 D20 = 1.5 N12 = 1.76182 .nu.12 = 26.5
R21 = -91.67 D21 = 0.2 R22 = 66.61 D22 = 3.3 N13 = 1.60311 .nu.13 =
60.7 R23 = -2072.51 D23 = Variable R24 = -67.27 D24 = 1.5 N14 =
1.77250 .nu.14 = 49.6 R25 = 29.73 D25 = 4.0 N15 = 1.80518 .nu.15 =
25.4 R26 = 92.37
[0096]
5 Variable Focal Length Separations 76.53 126.57 291.99 D5 4.00
28.75 59.00 D10 26.33 18.10 2.56 D16 4.00 12.23 27.77 D18 35.64
28.12 27.11 D23 20.82 16.71 3.47
NUMERICAL EXAMPLE 3
[0097] Focal Length: 75.99-291.99
[0098] F-Number: 4.05-5.75
6 R 1 = 94.35 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 61.27 D 2
= 7.3 N 2 = 1.51633 .nu.2 = 64.2 R 3 = -757.11 D 3 = 0.2 R 4 =
313.60 D 4 = 3.6 N 3 = 1.48749 .nu.3 = 70.2 R 5 = -481.24 D 5 =
Variable R 6 = -114.27 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 =
146.02 D 7 = 2.5 R 8 = -71.58 D 8 = 1.5 N 5 = 1.60311 .nu.5 = 60.7
R 9 = 41.03 D 9 = 3.3 N 6 = 1.84666 .nu.6 = 23.8 R10 = 109.42 D10 =
Variable R11 = 127.60 D11 = 3.6 N 7 = 1.48749 .nu.7 = 70.2 R12 =
-84.87 D12 = 0.2 R13 = 42.12 D13 = 5.3 N 8 = 1.51633 .nu.8 = 64.2
R14 = 76.46 D14 = 1.5 N 9 = 1.83400 .nu.9 = 37.2 R15 = 1363.46 D15
= 2.0 R16 = (Stop) D16 = Variable R17 = 65.36 D17 = 2.5 N10 =
1.51633 .nu.10 = 64.2 R18 = -78.94 D18 = Variable R19 = 76.31 D19 =
4.1 N11 = 1.69680 .nu.11 = 55.5 R20 = -43.97 D20 = 1.7 R21 = 38.11
D21 = 1.5 N12 = 1.84666 .nu.12 = 23.8 R22 = -111.62 D22 = Variable
R23 = -58.91 D23 = 1.5 N13 = 1.77250 .nu.13 = 49.6 R24 = 35.27 D24
= 3.0 R25 = 44.47 D25 = 3.7 N14 = 1.74077 .nu.14 = 27.8 R26 =
-473.11
[0099]
7 Variable Focal Length Separations 75.99 135.00 291.99 D5 4.00
29.99 59.00 D10 38.88 24.09 2.48 D16 4.00 12.96 28.08 D18 20.43
13.00 13.16 D22 19.05 15.18 2.99
[0100]
8TABLE 1 Condition Numerical Example No. Factor 1 2 3 (1)
.vertline.f4/fT.vertline. 2.262 1.197 2.689 (2)
.vertline.f2/fT.vertline. 0.155 0.135 0.149 (3)
.vertline.f6/fT.vertline. 0.166 0.177 0.231
[0101] According to the invention, as described above, the zoom
lens is constructed with six lens units of specified refractive
powers in total, wherein proper rules are set forth for the
refractive powers of the lens units and for the relation in which
the lens units move when zooming, so that the number of constituent
lenses is reduced to a minimum to insure that a shortening of the
total length of the entire lens system is achieved, while still
permitting high optical performance to be maintained throughout the
entire zooming range. Thus, a zoom lens of the telephoto type
having a range of about 4 is achieved.
[0102] Another embodiment in which further improvements are made is
described below.
[0103] Numerical examples 4 to 7 of zoom lenses of the invention
are shown in FIGS. 7(A), 7(B) and 7(B) through FIGS. 10(A), 10(B)
and 10(C). The aberrations of the zoom lenses of the numerical
examples 4 to 7 are shown in FIGS. 11(A), 11(B) and 11(C) through
FIGS. 14(A), 14(B) and 14(C), with suffix (A) in the wide-angle
end, suffix (B) in a middle position and suffix (C) in the
telephoto end.
[0104] The zoom lens comprises, from front to rear, a first lens
unit L1 of positive refractive power, a second lens unit L2 of
negative refractive power, a third lens unit L3 of positive
refractive power, a fourth lens unit L4 of negative refractive
power, a fifth lens unit L5 of positive refractive power and a
sixth lens unit L6 of negative refractive power. SP stands for a
stop. The arrows indicate the loci of motion of the lens units when
zooming from the wide-angle end to the telephoto end.
[0105] One of the characteristic features of the present embodiment
is that, for zooming purposes, certain ones of the lens units are
made to move in such relation as illustrated.
[0106] In more detail, when zooming from the wide-angle end to the
telephoto end, the separation between the first and second lens
units increases, the separation between the second and third lens
units decreases, the separation between the third and fourth lens
units increases, the separation between the fourth and fifth lens
unit increases and the separation between the fifth and sixth lens
units decreases.
[0107] Along with this, an additional condition is set forth as
follows:
0.3<ln Z.sub.2/ln Z<1 (4)
[0108] where ln represents natural logarithm wherein Z.sub.2 is the
zoom ratio of the second lens unit and Z is the zoom ratio of the
entire system.
[0109] When these features or conditions are satisfied, a proper
effect of varying the focal length is produced, thereby making it
easier to extend the zooming range, while still permitting a
shortening of the total length of the entire system to be achieved.
The stop SP is made axially movable in unison with the third lens
unit.
[0110] It is to be noted that, for the numerical examples 4, 5 and
6, the second and fourth lens units remain stationary during
zooming. For the numerical example 7, the second, fourth and sixth
lens units remain stationary during zooming.
[0111] In the zoom lens of the invention, for the wide- angle end,
the first and second lens units are positioned so closely that
their combined refractive power becomes negative. The third and
fourth lens units and also the fifth lens unit are positioned close
to each other. In addition, the third and those that follow have
their overall refractive power made negative. With these, the lens
system takes as a whole the retrofocus type.
[0112] For the telephoto end, the first and second lens units are
spaced apart largely. The second and third lens units are
positioned so closely that their combined refractive power becomes
negative. The fifth and sixth lens units are positioned so closely
that their combined refractive power becomes negative or weakly
positive. The stop is positioned adjacent to the third lens unit.
With these, the lens system takes as a whole the telephoto
type.
[0113] In the present invention, by using the lens configuration as
such, the refractive power arrangement is made to be nearly of the
retrofocus type in the wide-angle end. Nonetheless, the rearmost or
sixth lens unit is permitted to be a negative lens unit, thereby
well correcting coma and other asymmetric aberrations. Along with
this, it is in the telephoto end that as the refractive power
arrangement takes the telephoto type, compact form is produced and
at the same time spherical aberration and others are corrected
well.
[0114] In particular, the separation between the fourth and fifth
lens units is made wider in the telephoto end than in the
wide-angle end. This decreases the amount of spherical aberration
produced from the fifth lens unit in the telephoto end, thus
reducing the contribution of the sixth lens unit to the correction
of spherical aberration for the telephoto end.
[0115] Next, an explanation is given to the technical significance
of the above-described condition (4). The factor in this condition
represents how much share the second lens unit should take in
varying the focal length of the entire system. Mainly in view of
well correcting the variation of all aberrations with zooming, the
inequalities of condition (4) give a possible rang for the
contribution of the second lens unit to the variation of the focal
length. When the lower limit of the condition (4) is exceeded, as
this means that the second lens unit takes too small a share in
varying the focal length, or the zoom ratio of the second lens unit
is too small as compared with the zoom ratio of the entire system,
the contribution of third lens unit and those that follow to the
variation of the focal length becomes greater. In the case of
laying a large proportion of the zoom ratio on the third lens unit
and those that follows, because the total movement of each of these
lens units cannot be taken so much long, such a violation would
result in strengthening the refractive power of every one of the
lens units. As a result, all aberrations could be hardly corrected
without having to increase the number of constituent lenses
objectionably.
[0116] Conversely when the upper limit of the condition (4) is
exceeded, as this means that the second lens unit takes too large a
share in varying the focal length, or the zoom ratio of the second
lens unit is too high as compared with the zoom ratio of the entire
system, the third lens unit and the later has to perform inverse
variation of the focal length, thus worsening the efficiency with
which to vary the focal length. In order to perform a great
variation of the focal length by the second lens unit, the movement
of the second lens unit has to increase largely. This is
disadvantageous at improving the compact form. Further, as the
varied amount of aberrations by the first and second lens units
increases, the number of constituent lenses in each lens unit is
caused to increase objectionably.
[0117] Incidentally, in the invention, on correction of
aberrations, it is further preferable to alter the range for the
factor of the condition (4) as follows:
0.5<ln Z.sub.2/ln Z<1 (4a)
[0118] The zoom lens of the invention uses six lens units whose
refractive powers are of the signs described above, and zooming is
performed by varying the separations as specified above when
zooming from the wide-angle end to the telephoto end. Further, by
determining the contribution to the variation of the focal length
based on the condition (4). The aberrations are corrected
particularly well and high optical performance is obtained
throughout the entire zooming range.
[0119] In the invention, to further reduce the range of variation
of aberrations with zooming and to obtain high optical performance
throughout the entire area of the image frame, it is preferred to
satisfy the following condition:
0.5<fl/{square root}{square root over (fW.times.fT)}<3.0
(5)
[0120] where fl is the focal length of the first lens unit, and fW
and fT are the shortest and longest focal lengths of the entire
system.
[0121] The inequalities of condition (5) are to determine the
relationship between the focal length of the first lens unit of
positive refractive power and the focal lengths of the entire
system for the wide-angle and telephoto ends. Being combined with
the before described condition (4), the condition (5) gives a range
for the refractive power of the first lens unit, as is necessary
for the second lens unit to contribute to the variation of the
focal length. When the lower limit of the condition (5) is
exceeded, as this means that the focal length of the first lens
unit is too small, it becomes difficult to correct coma and
astigmatism mainly in the telephoto end. Conversely when the focal
length of the first lens unit is too long as exceeding the upper
limit, the zooming movement of the first lens unit must be
increased largely, causing the total length of the entire system to
increase objectionably.
[0122] In the invention, at least one of the second, fourth and
sixth lens units is made stationary during zooming. With this,
despite the use of the 6-unit type or a relatively large number of
lens units, it is made possible to limit the number of movable lens
units for zooming to a minimum.
[0123] In the invention, the fourth lens unit is constructed with a
single lens or a cemented lens of meniscus form convex toward the
object side or image side, thereby well correcting the variation of
mainly spherical aberration with zooming. The third lens unit is
constructed with a positive lens and cemented lens of a positive
lens and a negative lens to form two groups with three members. The
fifth lens unit is constructed with a cemented lens of a negative
lens and a positive lens to form one group with two members. The
sixth lens unit is constructed with a cemented lens of a negative
lens and a positive lens to form one group with two members. With
these, the variation of aberrations with zooming is corrected for
high optical performance throughout the entire zooming range.
[0124] Next, numerical examples 4 to 7 of the invention are shown.
In the numerical data for the examples 4 to 7, Ri is the radius of
curvature of the i-th lens surface, when counted from the object
side, Di is the i-th axial thickness or air separation, when
counted from the object side, and Ni and .upsilon.i are
respectively the refractive index and Abbe number of the glass of
the i-th lens element, when counted from the object side.
NUMERICAL EXAMPLE 4
[0125] Focal Length: 76.50-293.52; F-Number: 4.1-5.8
9 R 1 = 88.37 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 58.63 D 2
= 6.8 N 2 = 1.51633 .nu.2 = 64.2 R 3 = 2198.36 D 3 = 0.2 R 4 =
184.51 D 4 = 4.6 N 3 = 1.48749 .nu.3 = 70.2 R 5 = -437.16 D 5 =
Variable R 6 = -109.28 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 =
68.67 D 7 = 4.5 R 8 = -43.04 D 8 = 1.5 N 5 = 1.51633 .nu.5 = 64.2 R
9 = 71.91 D 9 = 3.5 N 6 = 1.84666 .nu.6 = 23.8 R10 = -762.51 D10 =
Variable R11 = 91.13 D11 = 4.3 N 7 = 1.60311 .nu.7 = 60.7 R12 =
-79.05 D12 = 0.2 R13 = 55.87 D13 = 4.5 N 8 = 1.48749 .nu.8 = 70.2
R14 = -78.29 D14 = 1.5 N 9 = 1.83400 .nu.9 = 37.2 R15 = 302.40 D15
= 2.5 R16 = (Stop) D16 = Variable R17 = -37.76 D17 = 2.5 N10 =
1.51633 .nu.10 = 64.2 R18 = -42.46 D18 = Variable R19 = 50.91 D19 =
2.0 N11 = 1.80518 .nu.11 = 25.4 R20 = 30.74 D20 = 6.0 N12 = 1.51633
.nu.12 = 64.2 R21 = -106.16 D21 = Variable R22 = -41.02 D22 = 1.5
N13 = 1.77250 .nu.13 = 49.6 R23 = 73.44 D23 = 3.7 N14 = 1.80518
.nu.14 = 25.4 R24 = -197.05
[0126]
10 Variable Focal Length Separations 76.50 133.51 293.52 D5 4.00
31.50 59.00 D10 32.94 21.72 2.50 D16 4.0 15.22 34.44 D18 17.41
11.35 34.10 D22 27.83 22.54 3.00
ln Z.sub.2/ln Z=0.8975; f1/{square root}{square root over
(fW.multidot.fT)}=0.8742
NUMERICAL EXAMPLE 5
[0127] Focal Length: 76.52 299.96; F-number: 4.1-5.8
11 R 1 = 101.86 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 66.06 D
2 = 6.8 N 2 = 1.51633 .nu.2 = 64.2 R 3 = -2991.10 D 3 = 0.2 R 4 =
160.98 D 4 = 4.6 N 3 = 1.48749 .nu.3 = 70.2 R 5 = -491.58 D 5 =
Variable R 6 = -141.58 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 =
63.57 D 7 = 4.5 R 8 = -45.92 D 8 = 1.5 N 5 = 1.51633 .nu.5 = 64.2 R
9 = 55.41 D 9 = 3.5 N 6 = 1.84666 .nu.6 = 23.8 R10 = 549.96 D10 =
Variable R11 = 101.98 D11 = 4.3 N 7 = 1.60311 .nu.7 = 60.7 R12 =
-97.26 D12 = 0.2 R13 = 60.55 D13 = 4.5 N 8 = 1.48749 .nu.8 = 70.2
R14 = -58.42 D14 = 1.5 N 9 = 1.83400 .nu.9 = 37.2 R15 = 2309.85 D15
= 2.5 R16 = (Stop) D16 = Variable R17 = 62.59 D17 = 4.0 N10 =
1.51633 .nu.10 = 64.2 R18 = 46.98 D18 = Variable R19 = 75.37 D19 =
2.0 N11 = 1.80518 .nu.11 = 25.4 R20 = 47.71 D20 = 6.0 N12 = 1.51112
.nu.12 = 60.5 R21 = -107.42 D21 = Variable R22 = -43.25 D22 = 1.5
N13 = 1.77250 .nu.13 = 49.6 R23 = -137.02 D23 = 3.7 N14 = 1.80518
.nu.14 = 25.4 R24 = -69.56
[0128]
12 Variable Focal Length Separations 76.52 156.31 299.96 D5 4.00
31.50 59.00 D10 41.16 22.48 3.90 D16 4.00 22.68 41.26 D18 17.90
-3.18 20.03 D22 45.25 31.82 8.27
ln Z.sub.2/ln Z=0.8799; f1/{square root}{square root over
(fW.multidot.fT)}=0.8644
NUMERICAL EXAMPLE 6
[0129] Focal Length: 77.37-291.70; F-number: 4.1-5.8
13 R 1 = 72.66 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 47.75 D 2
= 9.0 N 2 = 1.51633 .nu.2 = 64.2 R 3 = -421.68 D 3 = 0.2 R 4 =
189.95 D 4 = 4.6 N 3 = 1.48749 .nu.3 = 70.2 R 5 = 439.01 D 5 =
Variable R 6 = -94.89 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 =
51.91 D 7 = 4.5 R 8 = -73.79 D 8 = 1.5 N 5 = 1.51633 .nu.5 = 64.2 R
9 = 54.29 D 9 = 3.5 N 6 = 1.84666 .nu.6 = 23.8 R10 = 535.37 D10 =
Variable R11 = 55.67 D11 = 6.5 N 7 = 1.60311 .nu.7 = 60.7 R12 =
-57.70 D12 = 0.2 R13 = 54.57 D13 = 6.2 N 8 = 1.48749 .nu.8 = 70.2
R14 = 46.16 D14 = 1.5 N 9 = 1.83400 .nu.9 = 37.2 R15 = 589.80 D15 =
2.5 R16 = (Stop) D16 = Variable R17 = 37.95 D17 = 2.0 N10 = 1.80518
.nu.10 = 25.4 R18 = -29.85 D18 = 2.0 N11 = 1.51633 .nu.11 = 64.2
R19 = -404.46 D19 = Variable R20 = 55.41 D20 = 2.0 N12 = 1.80518
.nu.12 = 25.4 R21 = 26.63 D21 = 6.0 N13 = 1.51633 .nu.13 = 64.2 R22
= -48.33 D22 = Variable R23 = -36.80 D23 = 1.5 N14 = 1.77250 .nu.14
= 49.6 R24 = 66.11 D24 = 3.7 N15 = 1.80518 .nu.15 = 25.4 R25 =
-179.29
[0130]
14 Variable Focal Length Separations 77.37 114.23 291.70 D5 4.00
24.00 44.00 D10 33.17 26.84 0.60 D16 2.01 8.33 34.58 D19 10.91
12.19 14.95 D23 27.29 20.54 2.18
ln Z.sub.2/ln Z=0.5623; f1/{square root}{square root over
(fW.multidot.fT)}=0.8626
NUMERICAL EXAMPLE 7
[0131] Focal Length: 76.60-291.94; F-number: 4.1-5.8
15 R 1 = 105.68 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 66.24 D
2 = 6.8 N 2 = 1.51633 .nu.2 = 64.2 R 3 = -729.65 D 3 = 0.2 R 4 =
207.49 D 4 = 4.6 N 3 = 1.48749 .nu.3 = 70.2 R 5 = -314.15 D 5 =
Variable R 6 = -98.99 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 =
71.80 D 7 = 4.5 R 8 = -33.15 D 8 = 1.5 N 5 = 1.51633 .nu.5 = 64.2 R
9 = 81.89 D 9 = 3.5 N 6 = 1.84666 .nu.6 = 23.8 R10 = -162.12 D10 =
Variable R11 = 72.84 D11 = 4.3 N 7 = 1.60311 .nu.7 = 60.7 R12 =
-67.18 D12 = 0.2 R13 = 56.13 D13 = 4.5 N 8 = 1.48749 .nu.8 = 70.2
R14 = -56.03 D14 = 1.5 N 9 = 1.83400 .nu.9 = 37.2 R15 = 146.88 D15
= 2.5 R16 = (Stop) D16 = Variable R17 = -36.43 D17 = 2.5 N10 =
1.51633 .nu.10 = 64.2 R18 = -43.73 D18 = Variable R19 = 45.08 D19 =
2.0 N11 = 1.80518 .nu.11 = 25.4 R20 = 31.75 D20 = 7.0 N12 = 1.51112
.nu.12 = 60.5 R21 = -111.22 D21 = Variable R22 = -41.36 D22 = 1.5
N13 = 1.77250 .nu.13 = 49.6 R23 = 193.42 D23 = 3.7 N14 = 1.80518
.nu.14 = 25.4 R24 = -149.01
[0132]
16 Variable Focal Length Separations 76.60 119.14 291.94 D5 4.00
31.50 59.00 D10 35.27 27.29 2.12 D16 25.05 33.04 58.20 D18 5.62
8.76 25.13 D21 24.30 21.17 4.79
ln Z.sub.2/ln Z=0.9199; f1/{square root}{square root over
(fW.multidot.fT)}=0.8614
[0133] According to the invention, as described above, the zoom
lens is constructed with six lens units of specified refractive
power arrangement, and proper rules are set forth for the
refractive powers of the lens units and for the relation in which
the lens groups move to effect zooming. With these, the number of
constituent lenses is reduced and the total length of the entire
system is shortened, while still permitting high optical
performance to be maintained throughout the entire zooming range.
Thus, a zoom lens of the telephoto type having a range of about 4
with improvements of the image quality and compact form is
achieved.
[0134] Next, the above-described zoom lens is improved in order to
insure that part of this zoom lens can be decentered to stabilize
the image. Such a zoom lens is described below.
[0135] FIG. 15 is a diagram of geometry to explain the variation of
paraxial refractive power arrangement and FIGS. 16(A), 16(B) and
16(C) are longitudinal section view of a numerical example 8 of a
zoom lens employing the form of FIG. 15. FIG. 17 and FIGS. 18(A),
18(B) and 18(C) are a diagram of geometry and longitudinal section
views of a numerical example 9 of a zoom lens. In FIG. 15 and FIG.
17, the upper half represents the wide-angle side, and the lower
half the telephoto side. The arrows indicate the loci of the lens
units when zooming from the wide-angle end to the telephoto end. Of
the lens block diagrams, FIGS. 16(A) and 18(A) are in the
wide-angle end, FIGS. 16(B) and 18(B) are in a middle position and
FIGS. 16(C) and 18(C) in the telephoto end.
[0136] In the numerical example 8 of FIG. 15 and FIGS. 16(A), 16(B)
and 16(C), the zoom lens comprises, from front to rear, a first
lens unit L1 of positive refractive power, a second lens unit L2 of
negative refractive power, a third lens unit L3 of positive
refractive power, a fourth lens unit L4 of positive refractive
power and a fifth lens unit L5 of negative refractive power. SP
stands for a stop and IP for an image plane. When zooming from the
wide-angle end to the telephoto end, the second lens unit remains
stationary, while the first, third, fourth and fifth lens units
move axially in differential relation as indicated by the arrows.
The second lens unit is used as a decentering lens unit arranged on
vibrations of the optical system to move in directions
perpendicular to an optical axis to correct the shaking of an
image.
[0137] In the numerical example 9 of FIG. 17 and FIGS. 18(A), 18(B)
and 18(C), the zoom lens comprises, from front to rear, a first
lens unit L1 of positive refractive power, a second lens unit L2 of
negative refractive power, a third lens unit L3 of positive
refractive power, a fourth lens unit L4 of negative refractive
power, a fifth lens unit L5 of positive refractive power and a
sixth lens unit L6 of negative refractive power. SP stands for a
stop and IP for an image plane. When zooming from the wide-angle
end to the telephoto end, the second and fourth lens units remain
stationary, while the first, third, fifth and sixth lens units move
axially in differential relation as indicated by the arrows. The
second lens unit is used as a decentering lens unit arranged on
vibrations of the optical system to move in directions
perpendicular to an optical axis to correct the shaking of an
image.
[0138] As is understandable from the foregoing, the invention uses
at least three lens units in constructing a zoom lens. Of these, at
least two are made to move along a common optical axis to effect
zooming. In the space between the two movable lens units for
zooming there is positioned a lens unit stationary during zooming.
This lens unit is made to move to directions perpendicular to the
optical axis in such a way that when the optical system vibrates,
the shaking of an image is corrected.
[0139] In particular, in the invention, a zoom lens comprises, from
front to rear, a first lens unit having a positive refractive power
and axially movable for zooming, a second lens unit having a
negative refractive power and stationary during zooming, and a rear
lens unit comprised of at least one lens sub-unit, or a plurality
of lens sub- units, axially movable for zooming and whose overall
refractive power is positive, wherein the second lens unit is made
to move in directions perpendicular to the optical axis to correct
the shaking of an image when the optical system vibrates.
[0140] With the features described above, the invention is to
correct the shaking of the image with respect to a shooting line,
and at the same time to minimize the decentering aberrations the
second lens unit produces when moved (decentered) in the directions
perpendicular to the optical axis, thus maintaining good optical
performance.
[0141] In the numerical example 8 of FIG. 15 and FIGS. 16(A), 16(B)
and 16(C), letting the separation between the i-th and (i+1)st lens
units for the wide-angle end and the telephoto end be denoted by
DiW and DiT, respectively, when zooming from the wide-angle end to
the telephoto end, the selected ones of the lens units are moved in
such relation as to satisfy the following conditions:
[0142] D1W<D1T
[0143] D2W>D2T
[0144] D4W>D4T
[0145] In the numerical example 8, during zooming, the lens units
are moved so as to satisfy the above-described conditions, thereby
obtaining a zoom lens of high zoom ratio with minimization of the
entire lens system. It is to be noted that, in the present
embodiment, the second lens unit may otherwise be made axially
movable for zooming. According to this, it becomes easier to extend
the zooming range, and the variation of aberrations with zooming
can be corrected well.
[0146] In the numerical example 9 of FIG. 17 and FIGS. 18(A), 18(B)
and 18(C), letting the separation between the i-th and (i+1)st lens
units for the wide angle end and the telephoto end be denoted by
DiW and DiT, respectively, when zooming from the wide-angle end to
the telephoto end, the selected ones of the lens units are moved in
such relation as to satisfy the following conditions:
[0147] D1W<D1T
[0148] D2W>D2T
[0149] D3W<D3T
[0150] D5W>D5T
[0151] In the numerical examples 9, during zooming, the lens units
are moved in such relation as to satisfy the conditions described
above, thereby minimizing the size of the entire lens system, so
that a zoom lens of high range is obtained. It is to be noted that
in the present embodiment, the second lens unit may otherwise be
made axially movable for zooming. According to this, it becomes
easier to extend the zooming range. Also, the variation of
aberrations with zooming can be corrected well.
[0152] In the numerical examples 8 and 9, it is preferred to set
forth additional conditions in order to fulfill the requirements of
minimizing the bulk and size of the entire lens system and of
reducing the decentering aberrations when the shaking of an image
is corrected for good stability of optical performance. (i) The
focal length fa of the aforesaid decentering lens unit lies in a
range given by the following condition:
0.15<.vertline.fa/{square root}fW.multidot.fT.vertline.<0.5
(6)
[0153] where fw and fT are the shortest and longest focal lengths
of the entire system, respectively.
[0154] The inequalities of condition (6) give a range for the ratio
of the focal length of the decentering lens unit (second lens unit)
to the shortest and longest focal lengths of the zoom lens. When
the lower limit of the condition (6) is exceeded, as this means
that the focal length of the decentering lens unit is too short, it
becomes difficult to well correct the variation of aberrations with
zooming. So, the zoom ratio cannot be much extended as desired.
Another problem is that a few lens elements do not suffice for
making up the decentering lens unit. So, it is not suited to
improve the compact form.
[0155] Conversely when the upper limit of condition (6) is
exceeded, as this means the focal length of the decentering lens
unit is too long, it is advantageous at correcting various
aberrations, but the sensitivity of the decentering lens to
decentering (the ratio of the deviation of the decentering lens
unit to the deviation of the image with respect to the line of
sight) becomes impossible to increase. For this reason, the
movement of the decentering lens unit for correcting the shaking
must be increased. Moreover, the zooming movement of each lens unit
increases largely. This is contradictory to improvement of the
compact form.
[0156] (ii) Letting the overall focal lengths for the wide- angle
and telephoto ends of those lens units which are positioned on the
object side of the decentering lens unit be denoted by foW and foT,
respectively, and the overall focal lengths for the wide-angle and
telephoto ends of the decentering lens unit and those lens units
which lie on the object side of the decentering lens unit by frW
and frT, respectively, the following conditions are satisfied:
0.20<.vertline.foW/frW.vertline.<1.50 (7)
0.80<.vertline.foT/frT.vertline.<6.0 (8)
[0157] The inequalities of condition (7) give a range for the ratio
of the overall focal length for the wide-angle end of those lens
units which are positioned ahead of the decentering lens unit that
moves in the directions perpendicular to the optical axis when
stabilizing an image to the overall focal length of the decentering
lens unit and those that are positioned on the object side of the
decentering lens unit. The inequalities of condition (8) give a
range for the same except for the telephoto end.
[0158] The factors in the conditions (7) and (8) virtually
represent the ratio of the reduced angles of inclination of the
axial light ray in the paraxial zone before and after the
decentering lens unit that moves in the directions perpendicular to
the optical axis when correcting the shaking. When the refractive
power arrangement satisfies these conditions, good correction of
decentering aberrations results. Therefore, when the values of the
factors fall outside the ranges defined by the conditions (7) and
(8), problems arise in that a simple lens construction can no
longer correct decentering aberrations well and that the
decentering sensitivity can no longer be increased
sufficiently.
[0159] It is to be noted in connection with the conditions (7) and
(8) that the reason why the condition (7) is wider in the numerical
range than the condition (8) is that the displacement of the image
for an equivalent angle of vibration is smaller when in the wide-
angle end than in the telephoto end and, therefore, the amount of
decentering aberrations produced, too, becomes lesser.
[0160] Next, the optical features of the zoom lens having the image
stabilizing function of the invention are described below.
[0161] In general, if part of the optical system or one lens unit
is parallel decentered to correct the shaking of an image, the
image quality is caused to lower by the decentering aberrations
produced. Now assuming that in any refractive power arrangement, a
lens unit is made movable in directions perpendicular to the
optical axis for the purpose of correcting the shaking of an image,
an explanation will be made about the production of decentering
aberrations from the standpoint of the aberration theory on the
basis of the method revealed by Yoshiya Matsui at the 23rd lecture
meeting on applied physics in Japan (1962).
[0162] When part of the zoom lens, say lens unit P, is parallel
decentered by E, the amount of aberrations .DELTA.Y1 the entire
system produces is expressed by an equation (a) of the sum of the
amount of aberrations AY that occurs before the decentering and the
amount of decentering aberrations .DELTA.Y(E) produced by the
decentering. Here, the amount of aberrations .DELTA.Y is expressed
by spherical aberration (I), coma (II), astigmatism (III), Petzval
sum (P) and distortion (Y). The amount of decentering aberrations
.DELTA.Y(E) is expressed by an equation (c) of primary decentering
coma (IIE), primary decentering astigmatism (IIIE), primary
decentering curvature of field (PE), primary decentering distortion
(VE1), primary decentering distortion added aberration (VE2), and
primary original point movement (.DELTA.E).
[0163] Equations (d) to (i) for the aberrations (.DELTA.E) to (VE2)
are expressed under the condition that for the zoom lens having the
lens unit P made to parallel decenter, the on-axial and off-axial
light rays are incident on the lens unit P at an angle
.alpha..sub.p, .alpha.a.sub.p, by using the aberration coefficients
I.sub.p, II.sub.p, III.sub.p, P.sub.p and V.sub.p of the lens unit
P and also, as those lens units which are positioned on the image
side of the lens unit P are all taken as one q-th lens unit, by
using its aberration coefficients I.sub.q, II.sub.q, III.sub.q,
P.sub.q and V.sub.q.
.DELTA.Y1=.DELTA.Y+.DELTA.Y(E) (a)
.DELTA.Y=-(1/(2.alpha..sub.K'))((N.sub.1 tan .omega.) .sup.3 cos
.phi..omega..multidot.V+(N.sub.1 tan .omega.).sup.2R(2 cos
.phi..omega.cos(.phi..sub.R-.phi..omega.).multidot.III +cos
.phi..sub.R(III+P))+(N.sub.1 tan .omega.)R.sup.2(2 cos .phi..sub.R
cos(.phi..sub.R-.phi..omega.) +cos
.phi..omega.).multidot.II+R.sup.3 cos .phi..multidot.I) (b)
.DELTA.Y(E)=-(E/(2.alpha..sub.K'))((N.sub.1 tan
.omega.).sup.2((2+cos 2.phi..omega.)(VE1)-(VE2))+2(N.sub.1 tan
.omega.)R((2 cos (.phi..sub.R-.phi..omega.)
+cos(.phi..sub.R+.phi..omega.))(IIIE)+cos .phi..sub.R cos
.phi..omega..multidot.(PE)) +R.sup.2(2+cos
2.phi..sub.R)(IIE))-(E/(2.alpha..sub.K'))(.DELTA.E) (c)
(.DELTA.E)=-2(.alpha.'.sub.p-.alpha..sub.p)=-2h.sub.p.phi..sub.p
(d)
(IIE)=.alpha.a.sub.pII.sub.q-.alpha..sub.p(II.sub.p+II.sub.q)-.alpha.a.sub-
.p'I.sub.q+.alpha.a.sub.p(I.sub.p+I.sub.q)
=h.sub.p.phi..sub.pII.sub.q-.al-
pha..sub.pII.sub.p-(ha.sub.p.phi..sub.pII.sub.q-.alpha.a.sub.pI.sub.p)
(e)
(IIIE)=.alpha.'.sub.tIII.sub.q-.alpha..sub.p(III.sub.p+III.sub.q)-.alpha.a-
.sub.p'II.sub.q+.alpha.a.sub.p(II.sub.p+II.sub.q)
=h.sub.p.phi..sub.pIII.s-
ub.q-.alpha..sub.pIII.sub.p-(ha.sub.p.phi..sub.pII.sub.q-.alpha.a.sub.pII.-
sub.p) (f)
(PE)=.alpha.'.sub.pP.sub.q-.alpha..sub.p(P.sub.p+P.sub.q)
=h.sub.p.phi..sub.pP.sub.q-.alpha..sub.pP.sub.p (g)
(VE1)=.alpha.'.sub.pV.sub.q-.alpha..sub.p(V.sub.p+V.sub.q)-.alpha.a.sub.p'-
III.sub.q+.alpha.a.sub.p(III.sub.p+III.sub.q)
=h.sub.p.phi..sub.pV.sub.q-.-
alpha..sub.pV.sub.p-(ha.sub.p.phi..sub.pIII.sub.q-.alpha.a.sub.pIII.sub.p)
(h)
(VE2)=.alpha.a.sub.pP.sub.p-.alpha.a.sub.p(P.sub.p+P.sub.q)
=ha.sub.p.phi..sub.pP.sub.q-.alpha.a.sub.pP.sub.p (i)
[0164] From the equations described above, to minimize the
decentering aberrations produced, it is necessary to make small the
values of all the aberration coefficients I.sub.p, II.sub.p,
III.sub.p, P.sub.p and V.sub.p of the lens unit P, or to determine
them in good balance so that the aberration coefficients cancel
each other out as shown by the equations (a) to (i).
[0165] Next, the optical action of the zoom lens having the image
stabilizing function of the invention is described by taking a
model on the assumption that the photographic optical system shown
in FIG. 25 is moved in part in a direction perpendicular to the
optical axis to effect decentering, when the shaking of the image
is corrected.
[0166] First, to realize a sufficiently large correction by a
sufficiently small decentering movement, it is necessary to make
sufficiently large the primary original point movement (A E)
described above. With this in mind, a condition is considered for
correcting the primary decentering field curvature (PE). FIG. 25
shows a photographic optical system comprising, from front to rear,
an o-th lens unit, a p-th lens unit and a q-th lens unit, totaling
three lens units. Of these, the p-th lens unit is parallel moved in
the direction perpendicular to the optical axis to correct the
shaking of the image.
[0167] Here, the refractive powers of the o-th, p-th and q-th lens
units are denoted by .phi..sub.o, .phi..sub.p and .phi..sub.q,
respectively, the angles of incidence of the paraxial on- axial and
off-oxial light rays on any of these lens units by .alpha. and
.alpha.a, the heights of incidence of the paraxial on-axial and
off-axial light rays by h and ha. The aberration coefficients, too,
are expressed by using similar suffixes. It is also assumed that
the lens units each are constructed with a small number of lens
elements, and that each of the aberration coefficients tends to be
under-corrected individually.
[0168] Under such a premise, on looking at the Petzval sum of each
of the lens units, the Petzval sums P.sub.o, P.sub.p and P.sub.q of
the lens units are proportional to the refractive powers
.phi..sub.o, .phi..sub.p and .phi..sub.q of the lens units,
approximately satisfying the following relationships:
P.sub.o=C.phi..sub.o
P.sub.p=C.phi..sub.p
P.sub.q=C.phi..sub.q (where C is a constant) (1)
[0169] Therefore, the primary decentering field curvature (PE) that
is produced when the p-th lens unit is parallel decentered, can be
rearranged by inserting the equations described above as
follows:
(PE)=C.phi..sub.p(h.sub.p.phi..sub.p-.alpha..sub.p) (m)
[0170] To correct the decentering field curvature (PE), therefore,
either .phi..sub.p=0 or .phi..sub.q=.alpha..sub.p/h.sub.p must be
put. If .phi..sub.p=0 is used, the original point movement
(.DELTA.E) of first degree becomes "0" and correction of the
shaking becomes impossible to perform. So, a solution to satisfy
.phi..sub.q=.alpha..sub.p/h.sub.p has to be sought for. Because
h.sub.p>0, it is at least necessary to make a and 0 of the same
sign.
For .alpha..sub.p>0 (i)
[0171] To correct the decentering field curvature, .phi..sub.q>0
results. Again, inevitably .phi..sub.o>0 results. Further, at
this time, if .phi..sub.p>0,
0<.alpha..sub.p<.alpha.'.sub.p<1. Hence, the primary
original point movement (.DELTA.E) is given by the following
expression:
(.DELTA.E)=-2(.alpha..sub.p'-.alpha..sub.p)>-2 (n)
[0172] That is, the decenter sensitivity (the ratio of the
deviation of the image to the unity of deviation of the decentering
lens unit) becomes smaller than "1". If .phi..sub.p=0, as described
before, the decenter sensitivity is "0". Therefore, in such a case,
it is necessary to have .phi..sub.p<0.
For .alpha..sub.p<0 (ii)
[0173] To correct the decentering field curvature (PE),
.phi..sub.q<0 results. Again, inevitably .phi..sub.o<0
results. Therefore, further inevitably, .phi..sub.p>0
results.
[0174] From the above, to make sufficiently large the primary
original point movement (.DELTA.E) and make it possible to correct
the primary decentering field curvature (PE), the optical system
must take one of the following refractive power arrangements:
17 Lens Unit: o p q Power Arrangement a: plus minus plus b: minus
plus minus
[0175] These refractive power arrangements are illustrated in FIGS.
26(A) and 26(B) respectively.
[0176] In the invention, using such a refractive power arrangement,
the zoom lens is constructed. In general, for the zoom lens, proper
rules for the refractive powers of all the lens units are set forth
in order that a sufficiently large effect of varying the focal
length is realized with the entire system in the compact form and
at the same time all aberrations are corrected well. To this
purpose, it is better that those lens units which contribute to the
variation of the focal length have relatively strong refractive
powers. Also to well correct the variation of aberrations with
zooming, it is better that those lens units which have their
residual aberrations minimized within themselves are selected to be
movable for zooming.
[0177] Which one of the lens units of the zoom lens should be
selected to parallel decenter in directions perpendicular to the
optical axis when the shaking of an image is corrected is an
important problem. To form such a zoom lens, from the standpoints
of providing the possibility of sufficiently increasing the
decenter sensitivity and of making it relatively easy to correct
decentering aberrations, there is a method that one of the movable
lens units for zooming is applied directly to the parallel
decentering lens unit.
[0178] Meanwhile, for the purpose of improving the compact form of
the housing itself, it is desirable that, as the parallel
decentering lens unit, a lens unit of relatively short outer
diameter is selected. To prevent the operating mechanism from
becoming complicated, it is H-also desirable to select the fixed
lens unit for zooming as the parallel decentering lens unit.
[0179] In the invention, from the standpoints described above, the
zoom lens configuration to be used has the refractive power power
arrangement shown in FIG. 26(A) or 26(B), and the o-th and q-th
lens units are axially moved during zooming, while the p-th lens
unit remains stationary.
[0180] In the present invention, not only the movable lens units
for zooming are constructed in such a fundamental form, but also
the o-th and q-th lens units each may be either in the form of one
lens unit, or divided into a plurality of lens units. According to
this, it is possible to realize a zoom lens which is well corrected
for all aberrations. Though each of the foregoing embodiments has
been described as arranging the second lens unit to parallel
decenter, it is to be understood that, instead of the parallel
decentering, it may be rotated about a point on the optical axis so
that the shaking of the image is corrected.
[0181] Next, numerical examples 8 and 9 of the invention are shown.
In the numerical data for the examples 8 and 9, Ri is the radius of
curvature of the i- th lens surface, when counted from the object
side, Di is the i-th axial thickness or air separation, when
counted from the object side, and Ni aid .upsilon.i are
respectively the refractive index and Abbe number of the glass of
the i-th lens element, when counted from the object side.
NUMERICAL EXAMPLE 8
[0182]
18 R 1 = 101.63 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 65.89 D
2 = 6.8 N 2 = 1.51633 .nu.2 = 64.2 R 3 = 1548.89 D 3 = 0.2 R 4 =
207.11 D 4 = 4.2 N 3 = 1.48749 .nu.3 = 70.2 R 5 = -337.94 D 5 =
Variable R 6 = -125.77 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 =
151.03 D 7 = 2.8 R 8 = -67.50 D 8 = 1.5 N 5 = 1.61800 .nu.5 = 63.4
R 9 = 44.49 D 9 = 3.4 N 6 = 1.84666 .nu.6 = 23.8 R10 = 125.21 D10 =
Variable R11 = (Stop) D11 = 1.5 R12 = 157.70 D12 = 3.7 N 7 =
1.48749 .nu.7 = 70.2 R13 = -86.24 D13 = 0.2 R14 = 46.44 D14 = 5.7 N
8 = 1.60311 .nu.8 = 60.7 R15 = -78.17 D15 = 1.5 N 9 = 1.83400 .nu.9
= 37.2 R16 = 308.70 D16 = Variable R17 = 159.74 D17 = 4.6 N10 =
1.60311 .nu.10 = 60.7 R18 = -35.11 D18 = 1.5 N11 = 1.80518 .nu.11 =
25.4 R19 = -118.95 D19 = 0.2 R20 = 38.80 D20 = 4.0 N12 = 1.51633
.nu.12 = 64.2 R21 = 2284.84 D21 = Variable R22 = -68.32 D22 = 1.5
N13 = 1.77250 .nu.13 = 49.6 R23 = 34.06 D23 = 3.6 R24 = -162.72 D24
= 1.5 N14 = 1.69680 .nu.14 = 55.5 R25 = 98.00 D25 = 0.2 R26 = 49.20
D26 = 4.3 N15 = 1.80518 .nu.15 = 25.4 R27 = -185.92
[0183]
19 Variable Focal Length Separations 76.72 135.00 291.89 D 5 3.50
28.15 58.50 D10 37.00 21.31 2.00 D16 40.60 40.85 52.20 D21 9.70
8.40 2.00
.vertline.fa/{square root}{square root over
(fW.multidot.fT)}.vertline.=0.- 295
.vertline.foW/frW.vertline.=0.765
.vertline.foT/frT.vertline.=3.944
NUMERICAL EXAMPLE 9
[0184]
20 R 1 = 104.82 D 1 = 2.8 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 65.22 D
2 = 6.6 N 2 = 1.51633 .nu.2 = 64.2 R 3 = 1064.41 D 3 = 0.2 R 4 =
157.35 D 4 = 4.6 N 3 = 1.51633 .nu.3 = 64.2 R 5 = -339.86 D 5 =
Variable R 6 = -172.44 D 6 = 1.5 N 4 = 1.77250 .nu.4 = 49.6 R 7 =
63.56 D 7 = 4.9 R 8 = -34.89 D 8 = 1.5 N 5 = 1.51633 .nu.5 = 64.2 R
9 = 78.96 D 9 = 3.5 N 6 = 1.84666 .nu.6 = 23.8 R10 = -270.70 D10 =
Variable R11 = 63.23 D11 = 4.4 N 7 = 1.60311 .nu.7 = 60.7 R12 =
-77.78 D12 = 0.2 R13 = 57.33 D13 = 4.8 N 8 = 1.48749 .nu.8 = 70.2
R14 = -59.18 D14 = 1.5 N 9 = 1.83400 .nu.9 = 37.2 R15 = 210.50 D15
= 3.0 R16 = (Stop) D16 = Variable R17 = -58.16 D17 = 2.5 N10 =
1.60311 .nu.10 = 60.7 R18 = -77.22 D18 = Variable R19 = 177.20 D19
= 4.2 N11 = 1.60311 .nu.11 = 60.7 R20 = -42.39 D20 = 1.5 N12 =
1.80518 .nu.12 = 25.4 R21 = -88.25 D21 = 0.2 R22 = 56.85 D22 = 2.8
N13 = 1.51633 .nu.13 = 64.2 R23 = 218.49 D23 = Variable R24 =
-44.17 D24 = 1.5 N14 = 1.77250 .nu.14 = 49.6 R25 = 51.97 D25 = 3.3
N15 = 1.80518 .nu.15 = 25.4 R26 = 2229.01
[0185]
21 Variable Focal Length Separations 76.12 135.00 291.49 D 5 4.00
33.38 59.00 D10 31.30 20.57 2.00 D16 4.00 14.73 33.30 D18 23.80
18.20 21.60 D23 22.40 17.35 3.99
.vertline.fa/{square root}{square root over
(fW.multidot.fT)}.vertline.0.2- 75
.vertline.foW/frW.vertline.=0.335
.vertline.foT/frT.vertline.=1.068
[0186] According to the invention, the rules of design are set
forth as described above. When the shaking of an image is corrected
by moving part of the zoom lens in directions perpendicular to the
optical axis, a lens unit of small size and light weight is used as
the movable lens for decentering. Moreover, the large shaking of
the image can be corrected by a small movement of the decentering
lens unit. Further, when the decentering lens unit is decentered
nearly parallel, the produced amount of each of the decentering
aberrations described above is small. Thus, a zoom lens having the
image stabilizing capability and good optical performance can be
achieved.
[0187] In particular, according to the invention, all decentering
aberrations are well corrected, and a sufficiently large correction
is realized by a sufficiently small decentering movement. The lens
units other than the lens unit movable for decentering are made to
move axially to effect zooming. With these, a zoom lens having the
image stabilizing capability which is small in size and light in
weight and able to produce an image of high quality can be
achieved.
[0188] Next, another embodiment is described where further
improvements are made.
[0189] FIGS. 27(A), 27(B) and 27(C) to FIGS. 29(A), 29(B) and 29(C)
are longitudinal section views of numerical examples 10 to 12 of
zoom lenses of the invention. In these drawings, (A) shows the
zooming position for the wide angle end, (B) for a middle focal
length, and (C) for the telephoto end. The zoom lens comprises,
from front to rear, a first lens unit L1 of positive refractive
power, a second lens unit L2 of negative refractive power, a third
lens unit L3 of positive refractive power and a fourth lens unit L4
of positive refractive power. A stop SP is positioned on the object
side of the third lens unit L2 and arranged on zooming to move in
unison with the third lens unit L3. IP stands for an image plane.
The third lens unit L3 and the fourth lens unit L4 constitute a
rear lens unit L.sub.q. When zooming from the wide-angle end to the
telephoto end, the first lens unit L2, the third lens unit L3 and
the fourth lens unit L4 move axially toward the object side. When
the zoom lens vibrates, the shaking of the image is corrected (the
image is stabilized) by moving the second lens unit L2 as the
decentering lens unit in directions perpendicular to the optical
axis.
[0190] In the invention, the refractive powers of all the lens
units, the refractive power arrangement and other design parameters
are determined so as to include a wide angle region in which the
shortest focal length fW is shorter than the diagonal length of the
image frame.
[0191] In the invention, the focal length f.sub.p of the second
lens unit satisfies the following condition:
0.15<.vertline.f.sub.p/(fW.times.fT).sup.1/2.vertline.0.50
(9)
[0192] where fW and fT are the shortest and longest focal lengths
of the entire system, respectively.
[0193] The inequalities of condition (9) give a range for the ratio
of the focal length of the second lens unit as the decentering lens
unit to the shortest and longest focal lengths of the entire
system. When the lower limit of the condition (9) is exceeded, as
this means that the focal length of the decentering lens unit is
too short, a problem arises in that it becomes difficult to correct
the variation of aberrations with zooming and that the zoom ratio
cannot be made high enough. Another problem is that the decentering
lens unit cannot be constructed with a few lens elements, being not
suited to improve the compact form.
[0194] Conversely when the upper limit of the condition (9) is
exceeded, as this means that the focal length of the decentering
lens unit is too long, it is advantageous at correcting various
aberrations, but the decenter sensitivity of the decentering lens
unit (the ratio of the movement of the decentering lens unit to the
displacement of the image) cannot be made large. For this reason,
it becomes necessary to increase the movement of the decentering
lens unit for image stabilization. Another problem arises in that
the zooming movement of each of the lens units increases largely,
being not suited to improve the compact form.
[0195] Besides these, in the invention, the second lens unit is
made stationary during zooming to thereby facilitate minimization
of the size of the housing for the zoom lens and its operating
mechanism and to assure improvements of the precision accuracy of
the mounting mechanism for the lens system by limiting the
probability of occurrence of inclination of the lens units to a
minimum. (A) Next, in the invention, in a case where the third lens
unit L3 and the fourth lens unit L4 are treated as a rear lens unit
having at least one lens unit, the features are described
below.
[0196] (A-1) In the invention, the focal length f.sub.o of the
first lens unit, the focal length f.sub.q for the telephoto end of
the rear lens unit and the principal point interval e.sub.T for the
telephoto end between the first and second lens units satisfy the
following condition:
q<.vertline.f.sub.q/(f.sub.o-e.sub.T).vertline.<1.2 (10)
[0197] The inequalities of condition (10) are to properly determine
each of the focal lengths of the first lens unit and the rear lens
unit which are positioned before and after the second lens unit as
the decentering lens unit. In particular, on the assumption that
the Petzval sum of each of the lens units is nearly proportional to
the refractive power, when this condition is satisfied, it is made
possible to correct decentering aberrations well, in other words,
to achieve the before-described object by a simple lens
configuration. When the upper or lower limit of the condition (10)
is exceeded, as this means that the refractive power arrangement
over all the lens units is improper, it becomes difficult to
realize a zoom lens having the image stabilizing function with the
wide-angle region of the compact form. In the condition (10), the
lower limit may be altered to 0.6, and the upper limit to 1.0. If
so, it becomes easier to realize a zoom lens having a substantially
good image stabilizing function.
[0198] (A-2) The Petzval sums P.sub.p and P.sub.q of the second
lens unit and the rear lens unit, respectively, satisfy the
following condition:
1.1<.vertline.P.sub.p/P.sub.q<1.7 (11)
[0199] The inequalities of condition (11) give a range for the
ratio of the Petzval sums of the decentering lens unit L2 and the
rear lens unit that directly follows. When the lower limit of the
condition (11) is exceeded, as this means that the absolute value
of the Petzval sum of the decentering lens unit is relatively
small, it becomes difficult to correct decentering field curvature.
Conversely when the upper limit of the condition (11) is exceeded,
as this means that the absolute value of the Petzval sum of the
decentering lens unit is relatively large, the Petzval sum of the
entire lens system is liable to take a negative value. Therefore,
it becomes difficult to well correct field curvature in the
non-decentering state.
[0200] Also, in the condition (11), the lower limit may be altered
to 1.2, and the upper limit to 1.6. If so, it becomes easier to
realize a substantially further improved zoom lens. Also, in the
condition (11), the lower limit may be further increased to 1.3 and
the upper limit to 1.6. If lens materials that satisfy this
condition are selected, and the refractive power arrangement is
properly determined, it becomes easier to further improve the
correction of decentering field curvature.
[0201] (B) In another case where the third lens unit L3 and the
fourth lens unit L4 are considered to be independent of each other,
the invention has features described below.
[0202] (B-1) The focal length f.sub.o of the first lens unit, the
overall focal length f.sub.q for the telephoto end of the third and
fourth lens units and the principal point interval e.sub.T for the
telephoto end between the first and second lens units satisfy the
following condition:
0.5<.vertline.f.sub.q/(f.sub.o-e.sub.T).vertline.<1.2
(10a)
[0203] This condition should be satisfied from a similar reason to
that of the condition (10).
[0204] (B-2) The Petzval sum P of the second lens unit and the
total sum P of the Petzval sums of the third and fourth lens units
satisfy the following condition:
1.1<.vertline.P.sub.p/P.sub.q.vertline.<1.7 (12)
[0205] The inequalities of condition (12) give a range for the
ratio of the Petzval sum of the decentering lens unit L2 to the
Petzval sum of the lens units that follow toward the image side, or
the third and fourth lens units. When the lower limit of the
condition (12) is exceeded, as this means that the absolute value
of the Petzval sum of the decentering lens unit is relatively
small, it becomes difficult to correct decentering field curvature.
Conversely when the upper limit of the condition (12) is exceeded,
as this means that the absolute value of the Petzval sum of the
decentering lens unit is relatively large, the Petzval sum of the
entire optical system is liable to take a negative value and it
becomes difficult to correct field curvature well in the
non-decentering state.
[0206] Also in the condition (12), the lower limit may be altered
to 1.2 and the upper limit to 1.6. If so, it becomes easier to
realize a substantially improved zoom lens. Also, in the condition
(12), the lower limit may be further increased to 1.3 and the upper
limit to 1.6. If lens materials which satisfy this condition are
selected, and the refractive power arrangement is proper, it
becomes easier to well correct decentering aberration.
[0207] As has been described before, an optical system which
accomplishes the objects of the invention employs the refractive
power arrangement shown in FIG. 26(A).
[0208] Of course, the q-th lens unit described before may be either
one or even divided into a plurality of lens units. The latter is
more common for realizing a zoom lens well corrected for
aberrations.
[0209] So, in the invention, the zoom lens comprises, from front to
rear, a first lens unit of positive refractive power, a second lens
unit of negative refractive power and a rear lens unit comprised of
one or a plurality of lens units and having a positive overall
refractive power, totaling at least three lens units, wherein the
second lens unit is moved in directions perpendicular to the
optical axis when the shaking is corrected.
[0210] Here, the equation (m) is explained again. In the ordinary
photographic lens, if the object lies at infinity, the initial
values for the paraxial light ray can be set as follows:
.alpha..sub.o=0 (o)
h.sub.o=1 (p)
[0211] Here, using the paraxial ray tracing formula, the following
equations are obtained:
.alpha..sub.p=.alpha..sub.o+h.sub.o.phi..sub.o=.phi..sub.o (q)
h.sub.p=h.sub.o+e.sub.o.alpha..sub.p=1-e.sub.o.phi..sub.o (r)
[0212] where e.sub.o is the principal point interval between the
first and second lens units.
[0213] By inserting the equations (q) and (r) into the equation
(m), the following equation is obtained:
(PE)=c.phi..sub.p((1-e.sub.o.phi..sub.o).phi..sub.q-.phi..sub.o)
(s)
[0214] Therefore, to well correct primary decentering field
curvature (PE),
(1/.phi..sub.q)/((1/.phi..sub.o)-e.sub.o).div.1 (t)
[0215] should be established.
[0216] That is, it is desirable to determine the focal length
f.sub.o of the first lens unit, the focal length f.sub.q of the
rear lens unit and the principal point interval e.sub.o so as to
satisfy the following relationship:
f.sub.q/(f.sub.o-e.sub.o).div.1 (u)
[0217] Though the foregoing has been described on the assumption
that the Petzval sum of every lens unit is proportional to the
refractive power, it is in the rear lens unit that this
proportional relationship is not always established, depending on
the material of the lens and the number of constituent lenses. If
this proportional relationship is regarded as approximately valid,
the equation (u) defines a condition of correcting primary
decentering field curvature (PE).
[0218] Based on the consideration described above, the invention is
applied to a type of zoom lens that includes a wide-angle region in
which the shortest focal length of the entire system is shorter
than the diagonal length of the image frame. The zoom lens
comprises, from front to rear, a first lens unit of positive
refractive power, a second lens unit of negative refractive power
and a rear lens unit comprised of one or two or more lens units and
whose overall refractive power is positive, totaling at least three
lens units, wherein the second lens unit is made to move in
directions perpendicular to an optical axis to thereby stabilize
the image. Another rule of lens design is set forth for the foal
length f.sub.o of the first lens unit, the focal length f.sub.q of
the rear lens unit and the principal point interval e.sub.T between
the first and second lens units for the telephoto end. When this
rule or condition (10) is satisfied, a zoom lens having an image
stabilizing function which has solved the subject described before
is realized.
[0219] The inequalities of condition (10) has an equivalent
significance to thatof the equation (u) described before. Its upper
and lower limits are determined empirically. It should be pointed
out that, instead of the principal point interval e.sub.0 in the
equation (u), the factor in the condition (10) uses the principal
point interval for the telephoto end. The reason for this is that
the decenter sensitivity is higher when in the telephoto end than
when in the wide-angle end and therefore that the produced amount
of decentering aberrations for an equivalent decentering movement
increases largely with a high possibility when in the telephoto
end. It is, of course, desirable that, even for the wide-angle end,
the zoom lens configuration is made likewise to nearly satisfy the
equation (u).
[0220] The invention is still to apply such principles to more
specific zoom lenses. In the invention, as the zoom lens having the
image stabilizing function, choice is given mainly to standard zoom
lenses whose range includes from the wide-angle region to the
telephoto region. As a model embodying one form of this, the zoom
lens is made up, comprising, from front to rear, a first lens unit
of positive refractive power, a second lens unit of negative
refractive power, a third lens unit of positive refractive power
and a fourth lens unit of positive refractive power, that is, in
the 4-uit form.
[0221] First, as the lens unit which is made to move in directions
perpendicular to the optical axis to stabilize the image, on the
assumption that the refractive power arrangement of FIG. 26(A) is
used, the second lens unit of negative refractive power is
selected. Then, the refractive powers of all the lens units are
determined so as to satisfy the condition (10) described before. To
allow the decenter sensitivity of the decentering lens unit to
become high enough, the refractive power of the decentering lens
unit, too, is determined so as to satisfy the condition (9). With
these in mind, a fundamental framework for the zoom lens having the
image stabilizing function is realized.
[0222] To further improve the correction of decentering
aberrations, particularly decentering curvature of field, produced
when the decentering lens unit is decentered, it becomes necessary
to more rigorously reduce the decentering field curvature (PE)
expressed by the equation (g) described before. In the equation
(g), .alpha..sub.p and .alpha..sub.p' are the reduced angles of
inclination of the paraxial light rays and their values are
determined roughly depending on the refractive power arrangement
over all the lens units. What refractive power arrangement to
select for the given lens units suffers some degrees of limitation
under the condition that the zoom lens should be realized to a
sufficiently compact form and, therefore, cannot be altered much
freely. Also, P.sub.p and P.sub.q are the Petzval sums of the
decentering lens unit and that lens unit which is positioned on the
image side thereof, depending roughly on the refractive powers of
the lens units, but are possible to vary to some extent by
appropriately altering the number of lens elements in each of the
lens units and the materials from which the lens elements are made
up.
[0223] So, with the zoom lens having such a refractive power
arrangement, that is, the reduced angles of inclination
.alpha..sub.p and .alpha..sub.p' of the paraxial light rays, when
to further improve the correction of decentering aberrations,
particularly field curvature, produced when the decentering lens
unit is decentered, it becomes necessary to properly determine the
values of the Petzval sums P.sub.p and P.sub.q of the lens
units.
[0224] The condition (11) is set forth for the zoom lens having
such a refractive power arrangement and has a range determined
based on the consideration described above. When this condition is
satisfied, the Petzval sums of the lens units takes proper values.
In actual practice, there is a case where even when the Petzval
sums P.sub.p and P.sub.q are determined so as to satisfy the
condition (11), the equation (g) described above cannot be put to
"0". However, to realize a zoom lens having the image stabilizing
function to a compact form as a whole, it is desirable to satisfy
the condition (11).
[0225] Next, numerical examples 10 to 12 of the invention are
shown. In the numerical data for the examples 10 to 12, Ri is the
radius of curvature of the i-th lens surface, when counted from the
object side, Di is the i-th axial thickness or air separation, when
counted from the object side and Ni and 9i are respectively the
refractive index and Abbe number of the glass of the i-th lens
element, when counted from the object side.
NUMERICAL EXAMPLE 10
[0226] f=35.60-101.97 Fno.=3.60-4.60
22 R 1 = 220.00 D 1 = 2.5 N 1 = 1.80518 .nu.1 = 25.4 R 2 = 61.24 D
2 = 8.0 N 2 = 1.51633 .nu.2 = 64.2 R 3 = -134.30 D 3 = 0.2 R 4 =
37.37 D 4 = 4.8 N 3 = 1.69680 .nu.3 = 55.5 R 5 = 91.27 D 5 =
Variable R 6 = 57.75 D 6 = 1.5 N 4 = 1.69680 .nu.4 = 55.5 R 7 =
14.23 D 7 = 4.4 R 8 = -46.08 D 8 = 1.2 N 5 = 1.69680 .nu.5 = 55.5 R
9 = 33.37 D 9 = 1.0 R10 = 26.83 D10 = 2.9 N 6 = 1.84666 .nu.6 =
23.8 R11 = -323.36 D11 = 1.5 R12 = -23.12 D12 = 1.2 N 7 = 1.77250
.nu.7 = 49.6 R13 = -48.97 D13 = Variable R14 = (Stop) D14 = 1.0 R15
= 30.87 D15 = 3.7 N 8 = 1.51633 .nu.8 = 64.2 R16 = -45.12 D16 = 0.2
R17 = 31.86 D17 = 5.2 N 9 = 1.51633 .nu.9 = 64.2 R18 = -16.35 D18 =
1.2 N10 = 1.83400 .nu.10 = 37.2 R19 = 202.89 D19 = Variable R20 =
-53.43 D20 = 3.3 N11 = 1.60311 .nu.11 = 60.7 R21 = -19.10 D21 = 0.2
R22 = 56.40 D22 = 3.0 N12 = 1.65160 .nu.12 = 58.5 R23 = -78.57 D23
= 5.2 R24 = -18.51 D24 = 1.5 N13 = 1.80610 .nu.13 = 41.0 R25 =
-72.51
[0227]
23 Variable Focal Length Separations 35.60 70.00 101.97 D 5 2.50
17.66 24.50 D13 14.50 6.34 1.50 D19 9.30 7.80 8.10
[0228] Diagonal Length of Image Frame: 43.27
[0229] f.sub.o=70.02
[0230] f.sub.p=-17.07
[0231] f.sub.q=26.76
[0232] f.sub.T=31.64
.vertline.f.sub.q/(f.sub.o-e.sub.T).vertline.=0.697
.vertline.f.sub.p/(fW.multidot.fT).sup.1/2.vertline.=0.283
.vertline.P.sub.p/P.sub.q.vertline.=1.286
NUMERICAL EXAMPLE 11
[0233] f=35.97-101.72 Fno.=4.40-4.80
24 R 1 = 107.93 D 1 = 2.5 N 1 = 1.80518 .nu. 1 = 25.4 R 2 = 48.11 D
2 = 7.6 N 2 = 1.51633 .nu. 2 = 64.2 R 3 = -583.75 D 3 = 0.2 R 4 =
34.64 D 4 = 5.9 N 3 = 1.51633 .nu. 3 = 64.2 R 5 = 289.32 D 5 =
Variable R 6 = 153.82 D 6 = 1.5 N 4 = 1.69680 .nu. 4 = 55.5 R 7 =
15.13 D 7 = 5.2 R 8 = -64.57 D 8 = 1.2 N 5 = 1.69680 .nu. 5 = 55.5
R 9 = 46.43 D 9 = 0.5 R10 = 26.72 D10 = 3.2 N 6 = 1.84666 .nu. 6 =
23.8 R11 = 351.36 D11 = 2.0 R12 = 25.55 D12 = 1.2 N 7 = 1.69680
.nu. 7 = 55.5 R13 = -47.49 D13 = Variable R14 = (Stop) D14 = 1.0
R15 = 27.73 D15 = 2.9 N 8 = 1.69680 .nu. 8 = 55.5 R16 = -58.49 D16
= 0.2 R17 = 35.28 D17 = 3.7 N 9 = 1.51633 .nu. 9 = 64.2 R18 = 18.24
D18 = 1.2 N10 = 1.83400 .nu.10 = 37.2 R19 = 59.60 D19 = Variable
R20 = 279.17 D20 = 3.0 N11 = 1.69680 .nu.11 = 55.5 R21 = -18.24 D21
= 0.2 R22 = 41.35 D22 = 2.8 N12 = 1.60311 .nu.12 = 60.7 R23 =
-142.91 D23 = 2.0 R24 = -18.21 D24 = 1.2 N13 = 1.74400 .nu.13 =
44.8 R25 = 279.13
[0234]
25 Variable Focal Length Separations 35.97 70.00 101.72 D 5 2.00
11.80 17.70 D13 19.50 7.60 1.50 D19 9.30 8.18 8.84
[0235] Diagonal Length of Image Frame: 43.27
[0236] f.sub.o=65.01
[0237] f.sub.p=-18.99
[0238] f.sub.q=28.96
[0239] f.sub.T=25.55
.vertline.f.sub.q/(f.sub.o-e.sub.T)=0.734
.vertline.f.sub.p/(fW.multidot.fW).sup.1/2=0.314
.vertline.P.sub.p/P.sub.q=1.472
NUMERICAL EXAMPLE 12
[0240] f=36.11-102.00 Fno.=3.60-4.60
26 R 1 = 133.94 D 1 = 2.6 N 1 = 1.80518 .nu. 1 = 25.4 R 2 = 59.61 D
2 = 7.9 N 2 = 1.60311 .nu. 2 = 60.7 R 3 = -524.63 D 3 = 0.2 R 4 =
43.75 D 4 = 6.1 N 3 = 1.51633 .nu. 3 = 64.2 R 5 = 168.13 D 5 =
Variable R 6 = 86.79 D 6 = 1.5 N 4 = 1.80400 .nu. 4 = 46.6 R 7 =
15.28 D 7 = 5.0 R 8 = 36.46 D 8 = 1.2 N 5 = 1.80400 .nu. 5 = 46.4 R
9 = 93.00 D 9 = 0.5 R10 = 31.16 D10 = 3.8 N 6 = 1.80518 .nu. 6 =
25.4 R11 = -38.98 D11 = 1.0 R12 = -26.75 D12 = 1.3 N 7 = 1.80400
.nu. 7 = 46.6 R13 = -303.98 D13 = Variable R14 = (Stop) D14 = 1.5
R15 = 32.69 D15 = 3.8 N 8 = 1.69680 .nu. 8 = 55.5 R16 = -48.79 D16
= 0.2 R17 = 30.11 D17 = 2.7 N 9 = 1.51633 .nu. 9 = 64.2 R18 =
128.84 D18 = 2.4 R19 = -23.20 D19 = 9.5 N10 = 1.80518 .nu.10 = 25.4
R20 = 107.11 D20 = 1.0 R21 = -195.04 D21 = 3.4 N11 = 1.51742 .nu.11
= 52.4 R22 = -20.35 D22 = Variable R23 = 48.8 D23 = 4.4 N12 =
1.56732 .nu.12 = 42.8 R24 = -28.31 D24 = 3.0 R25 = -24.34 D25 = 1.6
N13 = 1.83400 .nu.13 = 37.2 R26 = -39.82 D26 = 2.0 R27 = -19.38 D27
= 1.8 N14 = 1.83400 .nu.14 = 37.2 R28 = -35.59
[0241]
27 Variable Focal Length Separations 36.11 70.00 102.00 D 5 2.00
20.54 28.40 D13 13.80 6.16 1.50 D22 5.80 2.99 2.44
[0242] Diagonal Length of Image Frame: 43.27
[0243] f.sub.o=80.00
[0244] f.sub.p=-17.62
[0245] f.sub.q=27.76
[0246] f.sub.T=37.41
.vertline.f.sub.q/(f.sub.o-e.sub.T).vertline.=0.652
.vertline.f.sub.p/(fW.multidot.fT).sup.1/2.vertline.=0.290
.vertline.P.sub.p/P.sub.q=1.296
[0247] According to the invention, as described above, part of the
optical system, or one lens unit, is made to move in directions
perpendicular to an optical axis when the shaking of an image is
corrected. Along with this, each lens element is properly arranged
to assist in well correcting all decentering aberrations. In
addition, it is realized that a sufficiently short decentering
movement suffices for correcting the sufficiently large shaking of
the image, thereby improving the compact form of the instrument as
a whole. Hence, it is possible to achieve a zoom lens having the
image stabilizing function suited to the standard zoom lens whose
range includes from a wide- angle region to the standard
region.
* * * * *