JP2007017532A - Image-shiftable zoom lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens that has a variable power as high as a variable power ratio of about seven to ten times, exhibits high performance such that an angle of view at a wide-angle end state is 75 degrees or more, and is image shiftable. <P>SOLUTION: The image-shiftable zoom lens includes, in order from an object, a first lens group G1 having positive refracting power, a second lens group G2 having negative refracting power, a third lens group G3 having positive power, a fourth lens group G4 having positive refracting power, and a fifth lens group G5 having positive refracting power. Upon changing a focal distance from a wide-angle end state W to a telephoto end state T, the first lens group G1 to fourth lens group G4 are moved, the fifth lens group G5 is fixed, the first partial lens group G3a of the third lens group G3, serving as a shift lens group, is shifted almost perpendicular to an optical axis, thereby shifting an image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image shiftable zoom lens suitable for a video camera, a digital still camera, or the like using a solid-state imaging device.

  2. Description of the Related Art Conventionally, for example, a digital still camera or a video camera that records a subject image using a solid-state imaging device such as a CCD or CMOS is generally equipped with a zoom lens, and many suitable zoom lenses have been proposed.

  Recently, in these cameras, there are an increasing number of zoom lenses having a high zoom ratio such that the zoom ratio (the focal length in the telephoto end state divided by the focal length in the wide-angle end state) is 7 to 10 times or more. A zoom lens having a high zoom ratio has an advantage that a subject at a long distance can be photographed large.

  However, these zoom lenses have a problem of failure in photographing due to camera shake, particularly on the telephoto side. Image blurring occurred during exposure due to minute camera shake (for example, camera shake that occurs when the photographer presses the release button) that occurred during shooting, and image quality deteriorated. Especially in zoom lenses with a high zoom ratio, when the angle of view at the telephoto end is narrow, the camera at the telephoto end has a larger camera shake angle than the wide-angle end. As the camera shifts from the state to the telephoto end state, even if the camera shake amount is constant, the image shake amount increases and the image is significantly degraded.

  Therefore, as an optical system that can shift the image of the zoom lens, a detection system that detects camera shake, an arithmetic system that controls the shift lens group according to a value output from the detection system, and a drive system that shifts the shift lens group A method of correcting image blur by driving a shift lens group so as to compensate for image blur caused by camera blur is known.

  Furthermore, by using an optical system capable of image shifting not only in the telephoto end state but also in the wide-angle end state, it is possible to use a slower shutter speed. It is also effective for shooting dim scenes. Increasing the number of scenes that can be shot and increasing the degree of freedom of shooting are also advantages of an optical system that can shift images.

Thus, in order to prevent a shooting failure due to camera shake, there has been proposed a zoom lens that corrects shake of a shot image by shifting a part of the optical system (see, for example, Patent Document 1).
JP 2000-298235 A

  In the zoom lens capable of image shifting disclosed in Patent Document 1, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power; And a fourth lens group having a positive refractive power and a fifth lens group having a positive refractive power, and the entire third lens group is moved in a direction substantially perpendicular to the optical axis, and the zoom lens is blurred. The camera shake is corrected.

  However, it is known that when the zoom ratio is increased and the focal length in the telephoto end state with respect to the diagonal length of the screen is increased, the image is blurred during exposure due to the influence of camera shake that occurs during shooting. When the camera blur amount is constant, the image blur amount increases as zooming and the angle of view becomes narrower, resulting in a marked deterioration of the captured image.

  In order to meet the user needs for image quality degradation and more stable image recording caused by camera shake caused by camera shake during shooting, the conventional optical system uses a brighter zoom lens system and a faster shutter speed. It was going. However, there is a problem that the zoom lens system tends to be large due to the large aperture.

  Further, in a zoom lens capable of image shift, a mechanism such as a detection system and a control system for detecting camera shake, a drive system for shifting a shift lens group, and the like are incorporated, and if the entire zoom lens system is large, There was a problem that it would become even larger when the mechanism was incorporated.

  In addition, in order to broaden the possibilities of photographer's shooting expression, there is an increasing demand for a zoom lens having a wide field angle such that the field angle in the wide-angle end state exceeds 75 degrees. Since a wider angle of view can be used, it is possible to enjoy shooting with a high degree of freedom.

  It is important to simultaneously satisfy the user's need to enjoy a higher degree of freedom of shooting and a reduction in image quality caused by camera shake caused by camera shake during shooting. For example, in Patent Document 1, optical performance in a state in which a part of the optical system is moved in a direction substantially perpendicular to the optical axis so as to have a function of canceling camera shake is maintained. However, the angle of view at the wide-angle end was about 60 degrees and the angle of view was insufficient.

  The present invention has been made in view of the above problems, and is a zoom lens having a high zoom ratio of about 7 to 10 times or higher, and a high angle of view exceeding 75 degrees in the wide-angle end state. An object of the present invention is to provide a zoom lens capable of image shift of performance.

  In order to solve the above-described problems, the present invention provides, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. Group, a fourth lens group having a positive refractive power, and a fifth lens group G5 having a positive refractive power, and when the focal length changes from the wide-angle end state to the telephoto end state, The lens group moves with respect to the image plane, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group decreases, and the third lens group decreases. The distance between the lens group and the fourth lens group decreases, the distance between the fourth lens group and the fifth lens group increases, and the third lens group includes an aperture stop and a positive aperture in order from the object side. A first partial lens group having a refractive power of 2 and a second partial lens group having a positive refractive power, It is possible to shift the image by shifting in a direction substantially perpendicular to partial lens unit in the optical axis, to provide an image shiftable zoom lens satisfies the following condition.

10.0 <f1 / fw <14.0
However, fw is the focal length of the entire zoom lens system capable of image shifting in the wide-angle end state, and f1 is the focal length of the first lens group.

  According to the present invention, there is provided a high-magnification zoom lens having a zoom ratio of about 7 to 10 times or more, and a high-performance image-shiftable zoom lens having an angle of view exceeding 75 degrees in a wide-angle end state. Can do.

  Hereinafter, embodiments of the present invention will be described.

  An image shiftable zoom lens according to an embodiment of the present invention (hereinafter simply referred to as a zoom lens) includes, in order from the object side, a first lens group having a positive refractive index and a second lens having a negative refractive index. A lens group, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power. When the focal length changes from the shortest state) to the telephoto end state (the longest focal length state), the first lens group moves relative to the image plane, and the distance between the first lens group and the second lens group is Change, the distance between the second lens group and the third lens group is decreased, the distance between the third lens group and the fourth lens group is decreased, and the distance between the fourth lens group and the fifth lens group is increased, The third lens group includes, in order from the object side, an aperture stop and a first partial lens having positive refractive power When made second lens subunit having a positive refractive power, a configuration capable of shifting the image by shifting in a direction substantially perpendicular to the optical axis of the first lens subunit as a shift lens group.

  With such a configuration, the zoom lens according to the present embodiment has an angle of view in the wide-angle end state exceeding 75 degrees and a zoom ratio of 7 to 10 times or more, and is excellent in image formation. Performance can be obtained.

  Next, the function of each lens group will be described.

  The first lens group has an effect of converging the light beam, and is arranged so that the off-axis light beam passes away from the optical axis by being as close as possible to the image plane in the wide-angle end state. Is made smaller. In the telephoto end state, the zoom lens system is shortened in total length by moving toward the object side so as to widen the distance from the second lens group, thereby enhancing the convergence effect.

  The second lens group functions to enlarge the image of the subject formed by the first lens group, and widens the distance between the first lens group and the second lens group from the wide-angle end state toward the telephoto end state. Thus, the enlargement ratio is increased and the focal length is changed.

  The third lens group has a function of converging the light beam expanded by the second lens group, and the third lens group is composed of a plurality of lens groups in order to achieve high performance.

  The first partial lens group in the third lens group needs to be in a state in which the spherical aberration, the sine condition, and the Petzval sum are well corrected so that the image is good when the lens is shifted. The correction of the spherical aberration and the sine condition is to suppress the eccentric coma aberration generated at the center of the screen when the shift lens group is shifted substantially perpendicular to the optical axis. The Petzval sum is corrected in order to suppress curvature of field that occurs at the periphery of the screen when the shift lens group is shifted substantially perpendicular to the optical axis.

  In the third lens group, the second partial lens group is arranged on the image side with an air gap from the first partial lens group, so that both lens groups move together while maintaining a fixed air gap during zooming. Aberration fluctuation due to zooming is minimized. Further, at the time of lens shift, only the first partial lens group is shifted substantially perpendicularly to the optical axis to perform image shift.

  The fourth lens group has a function of further converging the light beam converged by the third lens group, and by actively changing the interval between the third lens group and the fourth lens group when changing the focal length, It is possible to suppress fluctuations in the aberration of the image surface with respect to changes in the focal length.

  The fifth lens group is fixed during zooming, and adjusts the focus of the subject image formed by the first to fourth lens groups during focusing and controls the exit pupil position.

  In general, in a solid-state imaging device (CCD or the like), a microlens array is disposed immediately before the light receiving device in order to increase light receiving efficiency. For this reason, the optical system used in such a camera needs to move the exit pupil position away from the element surface, and the zoom lens according to the present embodiment achieves this with the fifth lens group.

Also, in an image shiftable zoom lens, when shifting the image by shifting the shift lens group in a direction substantially perpendicular to the optical axis, the image shift amount Δ with respect to the shift lens group movement amount δ is expressed by the following equation ( a).
(A) Δ = δ × (1−βa) βb
When transforming equation (a),
(B) Δ / δ = (1−βa) βb
Is obtained. Here, βa is the lateral magnification of the shift lens group, and βb is the lateral magnification of the lens group disposed on the image side of the shift lens group. Further, (1-βa) βb on the right side of the equation (b) is referred to as a blur coefficient.

Further, the focal length of the zoom lens system is expressed by the following equation (c).
(C) f = fa × βa × βb
When transforming equation (c),
(D) βb = f / (fa × βa)
Is obtained. Here, f is the focal length of the zoom lens system, and fa is the combined focal length on the object side of the shift lens group. fa × βa is the combined focal length on the object side of the shift lens group and the shift lens group.

If the expressions (b) and (c) are substituted into the expression (a),
Δ / δ = (1−βa) × f / (fa × βa)
(E) Δ / δ = (1−βa) / βa × f / fa
Is obtained.

  In the equation (e), when βa approaches 1, the ratio of the shift lens group movement amount δ to the image shift amount Δ approaches 0. That is, even if the shift lens is moved, the image does not move, and the image is not shifted. Further, when 1 / βa approaches 0, the ratio of the shift lens group movement amount δ to the image shift amount Δ is a condition that the image shift amount approaches 1 and image shift is possible. Even when f / fa is small, the image can be shifted.

  If the value of the blur coefficient on the right side of equation (b) increases, the shift amount of the image increases even if the shift lens group is slightly shifted, and the movement accuracy of the shift lens group becomes very strict and control becomes difficult. . On the other hand, when it becomes smaller, image shift is not performed unless the shift lens group is shifted more. In addition, the lens diameter is increased, and the configuration of the drive system is also increased. Therefore, it is necessary to appropriately define the blur coefficient value.

In addition, it is desirable that the zoom lens according to the present embodiment satisfies the following conditional expression (1) based on the above configuration.
(1) 10.0 <f1 / fw <14.0
Here, f1 is the focal length of the first lens group, and fw is the focal length of the entire zoom lens system in the wide-angle end state.

  Conditional expression (1) is a conditional expression for defining an optimum focal length range of the first lens group.

  When the upper limit of conditional expression (1) is exceeded, the refractive power of the first lens group becomes relatively weak, and the first lens group cannot effectively contribute to zooming, and the zoom ratio is A high zoom ratio of about 7 times or more cannot be secured. In addition, the amount of movement of the first lens group becomes large, and the fluctuation of aberration generated by the first lens group alone during zooming becomes large. As a result, performance degradation occurs in the entire zoom range from the wide-angle end state to the telephoto end state.

  If the lower limit value of conditional expression (1) is not reached, the refractive power of the first lens group becomes relatively strong, and the angle formed between the off-axis light beam incident on the first lens group and the optical axis at the wide angle side becomes smaller. If an angle of view exceeding 75 degrees in the wide-angle end state is reduced, the outer diameter of the first lens group is increased, which is contrary to the reduction in size. Further, since the refractive power of the first lens group becomes strong, the aberration generated by the first lens group alone becomes too large, and the object of the present invention to obtain excellent optical performance cannot be achieved.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (1) to 13.5. In order to further secure the effect of the present invention, it is more preferable to set the upper limit of conditional expression (1) to 13.0. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (1) to 10.5.

  In the zoom lens according to the present embodiment, when the focal length changes from the wide-angle end state to the telephoto end state, the fifth lens group may be fixed with respect to the image plane in the infinite focus state. desirable.

  In general, in a solid-state imaging device (CCD or the like), a microlens array is disposed immediately before the light receiving device in order to increase the light receiving efficiency. For this reason, in an optical system used for a digital still camera or the like, it is important to move the exit pupil position away from the element surface, and when zooming from the wide-angle end state to the telephoto end state by fixing the fifth lens group. The exit pupil position can be corrected well over the entire zoom range.

  In addition, in the zoom lens according to the present embodiment, it is desirable to configure the third lens group as follows in order to balance further performance enhancement and performance degradation during lens shift.

  In order from the object side, the third lens group has a positive refractive power composed of an aperture stop, a meniscus negative lens having a convex surface facing the object side, and a positive lens having a convex surface facing the object side. It consists of two lenses: a cemented lens (first partial lens group: positive lens group on the object side), a positive lens with a convex surface facing the object side, and a biconcave negative lens with a concave surface facing the image side It is desirable that the lens is composed of a cemented lens having a positive refractive power (second partial lens group: positive partial lens group on the image side).

  As described above, the first partial lens group needs to be corrected for spherical aberration and sine condition. The aberration can be corrected by a cemented lens having a positive refractive power, which is composed of a negative lens and a positive lens.

  In addition, the spherical aberration must be corrected in the entire third lens group to be in a predetermined off-axis aberration state. For this reason, the second partial lens group also needs to be corrected for spherical aberration. The second partial lens group is a cemented lens having a positive refracting power composed of two lenses, a positive lens and a negative lens, so that a decrease in performance can be minimized.

  In general, an image-shiftable lens group performs lens shift with a lens group close to an aperture stop in which an off-axis light beam passes near the optical axis during zooming in order to minimize performance degradation during lens shift. Therefore, it is possible to maintain good performance.

In addition, it is desirable that the zoom lens according to the present embodiment satisfies the following conditional expression (2).
(2) 1.0 <f3a / f3 <1.5
Here, f3 is the focal length of the third lens group, and f3a is the focal length of the first partial lens group.

  Conditional expression (2) defines an appropriate range for the focal length of the first partial lens group in the third lens group.

  If the upper limit value of conditional expression (2) is exceeded, the Petzval sum becomes positive and the diameter cannot be increased.

  When the lower limit of conditional expression (2) is not reached, the Petzval sum becomes negatively large. Further, it is not preferable because a larger lens shift amount is required to obtain a desired image shift amount, and the shift lens group becomes larger.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (2) to 1.45. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (2) to 1.10. In order to further secure the effect of the present invention, it is more preferable to set the lower limit of conditional expression (2) to 1.15.

In addition, it is desirable that the zoom lens according to the present embodiment satisfies the following conditional expression (3) in order to minimize the change in performance during lens shift.
(3) 0.8 <βbt × (1-βat) <1.2
Here, βat is the lateral magnification used of the first partial lens group in the telephoto end state, and βbt is the lateral magnification used in the entire lens system between the first partial lens group and the image plane in the telephoto end state. is there.

  Conditional expression (3) is a so-called blur coefficient, and is appropriate for the amount of movement of the first partial lens group in the telephoto end state from the optical axis in the vertical direction to the amount of movement of the image in the vertical direction from the optical axis. Range.

  If the upper limit of conditional expression (3) is exceeded, the amount of movement of the image relative to the amount of movement of the first partial lens unit from the optical axis becomes too large, and the first partial lens unit is moved by a minute amount. Since the image is greatly shifted, it becomes difficult to control the position of the shift lens group, and sufficient accuracy cannot be obtained.

  If the lower limit of conditional expression (3) is not reached, the amount of movement of the image relative to the amount of movement of the first partial lens unit from the optical axis becomes relatively small, so as to cancel image blur due to camera shake or the like. The required amount of movement of the shift lens group becomes extremely large. As a result, the drive mechanism for moving the shift lens group becomes large, and the lens diameter cannot be reduced.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (3) to 1.10. In order to further secure the effect of the present invention, it is more preferable to set the upper limit of conditional expression (3) to 1.05. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (3) to 0.90. In order to further secure the effect of the present invention, it is more preferable to set the lower limit of conditional expression (3) to 0.95.

In addition, it is desirable that the zoom lens according to the present embodiment satisfies the following conditional expression (4).
(4) 7.0 <f1 / | f2 | <11.0
Here, f2 is the focal length of the second lens group.

  Conditional expression (4) is a conditional expression for defining an appropriate range for the focal length ratio between the first lens group and the second lens group.

  If the upper limit of conditional expression (4) is exceeded, the refractive power of the first lens group becomes relatively weak, the first lens group cannot effectively contribute to zooming, and the zoom ratio is A high zoom ratio of about 7 times or more cannot be secured. In addition, the amount of movement of the first lens group becomes large, and the variation in aberration generated in the first lens group during zooming becomes large. As a result, it becomes difficult to suppress a decrease in performance in the entire zoom range from the wide-angle end state to the telephoto end state. Furthermore, since the refractive power of the second lens group becomes relatively strong, the occurrence of off-axis aberration cannot be suppressed, and high optical performance cannot be obtained.

  When the lower limit value of conditional expression (4) is not reached, the refractive power of the first lens group becomes relatively strong, and the angle formed between the off-axis ray incident on the first lens group and the optical axis on the wide-angle side is small. If an angle of view exceeding 75 degrees in the wide-angle end state is reduced, the outer diameter of the first lens group becomes large, which is contrary to the reduction in size. In addition, since the refractive power of the second lens group becomes relatively weak, the second lens group cannot effectively contribute to the zooming, and the zooming ratio is about 7 times or more. It will be impossible to secure.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (4) to 11.5. In order to further secure the effect of the present invention, it is more preferable to set the upper limit of conditional expression (4) to 11.0. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (4) to 7.5.

In addition, it is desirable that the zoom lens according to the present embodiment satisfies the following conditional expression (5).
(5) 0.10 <fw / f3a <0.20
Conditional expression (5) is a conditional expression for defining the focal length of the first partial lens group.

  When the upper limit of conditional expression (5) is exceeded, the refractive power of the first partial lens group becomes strong, and the aberration generated in the first partial lens group becomes large.

  If the lower limit value of conditional expression (5) is not reached, the refractive power of the first partial lens unit becomes weak and the afocal optical system is lost, so that the performance change becomes large when the lens is shifted. It is not preferable.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (5) to 0.19. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (5) to 0.11.

  In the zoom lens according to the present embodiment, it is desirable that the fifth lens unit is moved to the object side to perform focus adjustment from a long-distance object to a short-distance object.

  Thus, the fifth lens group adjusts the focus of the subject image formed by the first to fourth lens groups and controls the exit pupil position. By moving the fifth lens group during focus adjustment, the position of the exit pupil can be corrected more satisfactorily.

In addition, it is desirable that the zoom lens according to the present embodiment satisfies the following conditional expression (6).
(6) 4.0 <f5 / fw <9.0
Here, f5 is the focal length of the fifth lens group.

  Conditional expression (6) is a conditional expression for defining an appropriate focal length range of the fifth lens group.

  If the upper limit value of conditional expression (6) is exceeded, the refractive power of the fifth lens group becomes weak, which is advantageous for correcting various aberrations. However, the amount of movement during focus adjustment becomes large, and when moving, The drive system members and the like necessary for this increase in size and may interfere with other members. As a result, it becomes impossible to save space when storing in the camera body.

  If the lower limit of conditional expression (6) is not reached, the refractive power of the fifth lens group becomes strong, the aberration generated by the fifth lens group alone becomes too large, and the performance change during close-up shooting becomes large. It is not preferable. As a result, it becomes difficult to shorten the shortest shooting distance.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (6) to 8.5. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (6) to 4.2. In order to further secure the effect of the present invention, it is more preferable to set the lower limit of conditional expression (6) to 4.5.

  In the zoom lens according to the present embodiment, it is desirable to dispose at least one aspheric lens in the fourth lens group. By disposing an aspherical lens in the fourth lens group, it is possible to satisfactorily correct a variation in axial aberration that occurs in the fourth lens group alone.

  In the zoom lens according to the present embodiment, for image blur correction, a blur detection system that detects blur of the lens system and a driving unit are combined with the lens system, and the first partial lens group of the third lens group is combined. The shift lens group is configured to be decentered in a direction perpendicular to the optical axis to correct image blur (fluctuation in image plane position) caused by the blur of the lens system. The first partial lens constituting the lens system By decentering all or part of one of the lens groups other than the group as a shift lens group in a direction perpendicular to the optical axis, image blur caused by the blur of the lens system detected by the blur detection system ( It is also possible to correct the image blur by driving the shift lens group by the driving means and shifting the image so as to correct the fluctuation of the image plane position.

(Example)
Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a diagram showing the movement trajectory of each lens group in the refractive power distribution and the change in the focal length state from the wide-angle end state W to the telephoto end state T of the zoom lens according to each embodiment of the present invention.

  As shown in FIG. 1, the zoom lens according to each embodiment of the present invention includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, A filter group including a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a positive refractive power, a low-pass filter, an infrared cut filter, and the like. It consists of FL. When the focal length state changes from the wide-angle end state W to the telephoto end state T (ie, zooming), the first lens group G1 moves relative to the image plane I, and the first lens group G1 and the second lens group G2 are moved. The distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, and the fourth lens group G4 and the fourth lens group G4 The distance from the fifth lens group G5 increases, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side, the second lens group G2 moves, and the fifth lens group G5. Is fixed.

In each embodiment, the height of the aspheric surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangential plane of each vertex of the aspheric surface to each aspheric surface at height y. Where S (y) is R, the radius of curvature (vertex curvature radius) of the reference sphere is R, the conic constant is κ, and the nth-order aspherical coefficient is Cn.
S (y) = (y ² / R) / {1+ (1−κ × y ² / R ² ) ^1/2 }
+ C4 × y ⁴ + C6 × y ⁶ + C8 × y ⁸ + C10 × y ¹⁰
In each example, the secondary aspherical coefficient C2 is 0, and the vertex curvature radius R and the paraxial curvature radius r coincide with each other. In the lens data of each example, an aspherical surface is marked with * on the left side of the surface number.

[First embodiment]
FIG. 2 is a diagram showing a configuration of the zoom lens according to the first embodiment of the present invention.

  In FIG. 2, the first lens group G1 includes a cemented positive lens formed by bonding a negative meniscus lens L11 having a concave surface facing the image side in order from the object side and a biconvex positive lens L12, and a convex surface on the object side. It is composed of a positive meniscus lens L13 directed to it.

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. It consists of

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a is composed of, in order from the object side, a cemented positive lens formed by bonding a negative meniscus lens L31 having a concave surface facing the image side and a biconvex positive lens L32. The second partial lens group G3b is composed of a cemented positive lens formed by bonding a biconvex positive lens L33 and a biconcave negative lens L34 in order from the object side. By shifting the first partial lens group G3a in a direction substantially perpendicular to the optical axis, the image on the image plane I is shifted, and image quality deterioration due to camera shake or the like is corrected.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric surface on the image side, a biconvex positive lens L42, and a biconcave negative lens L43. It is composed of a cemented negative lens made by bonding.

  The fifth lens group G5 is composed of a cemented positive lens formed by bonding a biconvex positive lens L51 and a biconcave negative lens L52.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The aperture stop S is disposed closest to the object side of the third lens group G3, and moves integrally with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T.

  In the zoom lens of this embodiment, the fifth lens group G5 is moved to the object side to perform focus adjustment (focusing) from a long-distance object to a short-distance object.

  Table 1 below lists values of specifications of the zoom lens according to the first example of the present invention. In (Overall specifications) in the table, f is the focal length, F.F. NO represents the F number, 2ω represents the angle of view (unit: degree), and Bf represents the back focus. In (lens data), the surface number is the order of the lens surfaces from the object side along the direction in which the light beam travels, the radius of curvature is the radius of curvature of the lens surfaces, the surface interval is the lens surface interval, the refractive index and the Abbe Each number represents a value for the d-line (λ = 587.6 nm). Note that the refractive index of air of 1.000 000 is omitted, and the radius of curvature of 0.0000 represents a plane. (Aspheric data) shows the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants C4 to C10 of each aspheric surface. (Variable interval data) indicates the focal length f, the value of the variable interval, and the back focus Bf in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. In (conditional expression corresponding value), the corresponding value of each conditional expression is shown.

  In addition, in all the following specification values, “mm” is generally used as the focal length f, the radius of curvature, the surface interval and other lengths, etc. unless otherwise specified. Even if proportional reduction is performed, the same optical performance can be obtained. Further, the unit is not limited to “mm”, and other appropriate units may be used. In addition, the description of these symbols is the same in the following other embodiments, and the description is omitted.

(Table 1)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 7.31 to 25.90 to 74.15
F.NO = 2.76 to 3.89 to 5.17
2ω = 79.11 to 24.53 to 8.67

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 122.6426 2.00 1.84666 23.78
2 67.7364 7.60 1.65160 58.55
3 -1028.7917 0.16
4 45.8473 5.76 1.49782 82.52
5 109.9865 (d5)
6 65.9247 1.20 1.83481 42.71
7 10.9822 5.00
8 -42.7356 1.27 1.80400 46.57
9 18.4559 0.53
10 16.2393 4.32 1.84666 23.78
11 -30.7004 0.54
12 -20.4028 0.80 1.80400 46.57
13 99.2103 (d13)
14 0.0000 0.80 (Aperture stop S)
15 26.0353 0.88 1.80610 40.88
16 14.9176 3.20 1.49782 82.52
17 -39.3491 1.00
18 19.7164 3.19 1.48749 70.23
19 -16.7642 1.50 1.58313 59.37
20 40.0882 (d20)
21 23.2974 4.05 1.58913 61.25
* 22 -36.4868 0.10
23 14.9843 2.84 1.70154 41.24
24 -383.8313 0.80 1.72825 28.46
25 10.2279 (d25)
26 26.1278 2.50 1.75700 47.82
27 -500.0000 1.20 1.84666 23.78
28 95.9573 (d28)
29 0.0000 1.72 1.54437 70.51
30 0.0000 0.96
31 0.0000 0.50 1.51680 64.19
32 0.0000 (Bf)

(Aspheric data)
[22nd page]
R κ C4 C6 C8 C10
-36.4868 +2.5525 + 4.2527 × 10 ^-5 -1.4947 × 10 ^-7 + 4.4089 × 10 ^-9 -4.6296 × 10 ^-11

(Variable interval data)
Wide-angle end state Intermediate focal length state Telephoto end state
f 7.3130 25.9000 74.1501
d5 2.8000 29.9959 48.5802
d13 22.0612 8.0154 2.5000
d20 11.1574 2.3439 0.5379
d25 5.1608 20.8305 35.4940
d28 5.7863 5.7863 5.7863
Bf 1.0151 1.0150 1.0151

(Values for conditional expressions)
fw = 7.3130
f1 = 90.1775
f2 = -9.5537
f3 = 33.8394
f3a = 43.8944
f5 = 48.7650
βat = 2.2606
βbt = −0.8226
(1) f1 / fw = 12.33311
(2) f3a / f3 = 1.2971
(3) βbt × (1−βat) = 1.0370
(4) f1 / | f2 | = 9.4390
(5) fw / f3a = 0.1666
(6) f5 / fw = 6.6683

  FIG. 3 is a diagram showing various aberrations in the infinitely focused state with respect to the d-line (λ = 587.6 nm) of the zoom lens according to the first example, and (a) is a wide-angle end state (f = 7.31 mm). (B) shows various aberration diagrams in the intermediate focal length state (f = 25.90 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 74.15 mm).

  FIG. 4 is a lateral aberration diagram of the zoom lens according to the first example at the time of lens shift with respect to the d-line (λ = 587.6 nm). FIG. 4A is the lateral aberration in the wide-angle end state (f = 7.31 mm). Aberration diagrams, (b) shows lateral aberration diagrams in the intermediate focal length state (f = 25.90 mm), and (c) shows lateral aberration diagrams in the telephoto end state (f = 74.15 mm).

  In each aberration diagram, FNO represents an F number, Y represents an image height, and A represents a half field angle (unit: degree) with respect to each image height. In the astigmatism diagram, the solid line represents the sagittal image plane, and the broken line represents the meridional image plane. In the spherical aberration diagram, the solid line indicates the spherical aberration, and the broken line indicates the sine condition (sine condition). The coma aberration diagram shows each aberration with respect to the half angle of view A. Also, these symbols are the same in the other examples below, and the description thereof is omitted.

  As is apparent from each aberration diagram, the zoom lens according to the first example has excellent imaging performance with various aberrations corrected well in each focal length state from the wide-angle end state to the telephoto end state. I understand.

[Second Embodiment]
FIG. 5 is a diagram showing a configuration of a zoom lens according to the second embodiment of the present invention.

  In FIG. 5, the first lens group G1 includes a cemented positive lens formed by bonding a negative meniscus lens L11 having a concave surface facing the image side in order from the object side and a positive meniscus lens L12 having a convex surface facing the object side; It is composed of a positive meniscus lens L13 having a convex surface facing the side.

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. It consists of

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a includes, in order from the object side, a cemented positive lens formed by bonding a negative meniscus lens L31 having a concave surface facing the image side and a biconvex positive lens L32. The second partial lens group G3b is composed of a cemented positive lens formed by bonding a biconvex positive lens L33 and a biconcave negative lens L34 in order from the object side. By shifting the first partial lens group G3a in a direction substantially perpendicular to the optical axis, the image on the image plane I is shifted, and image quality deterioration due to camera shake or the like is corrected.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric surface on the image side, a biconvex positive lens L42, and a biconcave negative lens L43. It is composed of a cemented negative lens made by bonding.

  The fifth lens group G5 includes a cemented positive lens formed by bonding a positive meniscus lens L51 having a convex surface directed toward the object side and a negative meniscus lens L52 having a concave surface directed toward the image side.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The aperture stop S is disposed closest to the object side of the third lens group G3, and moves integrally with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T.

  In the zoom lens of this embodiment, the fifth lens group G5 is moved to the object side to perform focus adjustment (focusing) from a long-distance object to a short-distance object.

  Table 2 below provides values of specifications of the zoom lens according to the second example of the present invention.

(Table 2)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 7.31 to 27.23 to 74.15
F.NO = 2.73 to 3.86 to 5.00
2ω = 78.99 〜 23.30 〜 8.67

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 125.6867 1.80 1.84666 23.78
2 67.8325 7.05 1.69680 55.53
3 5219.0416 0.10
4 49.8182 5.85 1.49782 82.52
5 151.8211 (d5)
6 60.2359 1.20 1.83481 42.71
7 11.4013 5.00
8 -44.0857 1.20 1.80400 46.57
9 22.0419 1.40
10 19.3196 4.05 1.84666 23.78
11 -32.2769 0.50
12 -22.2314 0.80 1.80400 46.57
13 78.4505 (d13)
14 0.0000 0.80 (Aperture stop S)
15 30.2774 0.80 1.80610 40.92
16 16.9537 3.20 1.49782 82.52
17 -38.4719 1.00
18 20.0239 3.25 1.48749 70.23
19 -16.3449 0.90 1.56384 60.66
20 40.4349 (d20)
21 33.8057 4.05 1.58913 61.25
* 22 -31.5525 0.10
23 13.5000 3.40 1.61800 63.33
24 -97.1544 1.10 1.74950 35.28
25 10.7948 (d25)
26 19.6813 3.50 1.49700 81.54
27 123.6358 2.00 1.80518 25.42
28 100.0002 (d28)
29 0.0000 1.72 1.54437 '70.51
30 0.0000 0.96 1.00000
31 0.0000 0.50 1.51680 64.19
32 0.0000 (Bf)

(Aspheric data)
[22nd page]
R κ C4 C6 C8 C10
-31.5525 +6.5279 + 4.8222 × 10 ^-5 -2.9856 × 10 ^-8 + 3.3439 × 10 ^-9 -2.5394 × 10 ^-11

(Variable interval data)
Wide-angle end state Intermediate focal length state Telephoto end state
f 7.3130 27.2316 74.1500
d5 2.7953 30.3814 48.0353
d13 25.5561 8.6466 2.6048
d20 12.8639 3.9223 2.8261
d25 5.0135 21.9932 36.3460
d28 4.1093 4.1093 4.1093
Bf 0.9900 0.9900 0.9900

(Values for conditional expressions)
fw = 7.3130
f1 = 89.8269
f2 = -10.1353
f3 = 34.7673
f3a = 47.1639
f5 = 49.3397
βat = 2.301
βbt = -0.7685
(1) f1 / fw = 12.22832
(2) f3a / f3 = 1.3566
(3) βbt × (1−βat) = 0.9999
(4) f1 / | f2 | = 8.8628
(5) fw / f3a = 0.1551
(6) f5 / fw = 6.7468

  FIG. 6 is a diagram of various aberrations of the zoom lens according to the second example in the infinite focus state with respect to the d-line (λ = 587.6 nm). FIG. 6A is a wide-angle end state (f = 7.31 mm). (B) shows various aberration diagrams in the intermediate focal length state (f = 27.23 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 74.15 mm).

  FIG. 7 is a lateral aberration diagram at the time of lens shift with respect to the d-line (λ = 587.6 nm) of the zoom lens according to the second example, and FIG. 7A is the lateral aberration in the wide-angle end state (f = 7.31 mm). The aberration diagram, (b) shows the lateral aberration diagram in the intermediate focal length state (f = 27.23 mm), and (c) shows the lateral aberration diagram in the telephoto end state (f = 74.15 mm).

  As is apparent from each aberration diagram, the zoom lens according to the second example has excellent imaging performance with various aberrations corrected well in each focal length state from the wide-angle end state to the telephoto end state. I understand.

[Third embodiment]
FIG. 8 is a diagram showing a configuration of a zoom lens according to the third example of the present invention.

  In FIG. 8, the first lens group G1 includes a cemented positive lens formed by bonding a negative meniscus lens L11 having a concave surface directed toward the image side and a positive meniscus lens L12 having a convex surface directed toward the object side, and an object. It is composed of a positive meniscus lens L13 having a convex surface facing the side.

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. It consists of

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a is composed of, in order from the object side, a cemented positive lens formed by bonding a negative meniscus lens L31 having a concave surface facing the image side and a biconvex positive lens L32. The second partial lens group G3b is composed of a cemented positive lens formed by bonding a biconvex positive lens L33 and a biconcave negative lens L34 in order from the object side. By shifting the first partial lens group G3a in a direction substantially perpendicular to the optical axis, the image on the image plane I is shifted, and image quality deterioration due to camera shake or the like is corrected.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric image side surface, a positive meniscus lens L42 having a convex surface facing the object side, and a concave surface on the image side. It is composed of a cemented negative lens that is formed by bonding with a negative meniscus lens L43 directed to it.

  The fifth lens group G5 is composed of a cemented positive lens formed by bonding a biconvex positive lens L51 and a biconcave negative lens L52.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The aperture stop S is disposed closest to the object side of the third lens group G3, and moves integrally with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T.

  In the zoom lens of this embodiment, the fifth lens group G5 is moved to the object side to perform focus adjustment (focusing) from a long-distance object to a short-distance object.

  Table 3 below lists values of specifications of the zoom lens according to the third example of the present invention.

(Table 3)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 7.31 to 27.48 to 74.15
F.NO = 2.78 to 4.04 to 5.24
2ω = 79.09 〜 23.17 〜 8.67

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 97.4770 1.80 1.84666 23.78
2 59.4591 7.30 1.65160 58.55
3 524.4776 0.10
4 52.1087 5.80 1.49782 82.52
5 204.9638 (d5)
6 55.4805 1.20 1.83481 42.71
7 10.6897 5.44
8 -32.3153 1.30 1.77250 49.60
9 23.3868 0.50
10 18.5497 4.35 1.84666 23.78
11 -26.7997 0.48
12 -19.7645 0.80 1.80440 39.58
13 147.1549 (d13)
14 0.0000 0.80 (Aperture stop S)
15 30.8781 1.41 1.80610 40.92
16 17.2152 3.20 1.49782 82.52
17 -36.0844 1.00
18 22.3687 3.30 1.48749 70.23
19 -14.3457 1.85 1.56384 60.66
20 50.0000 (d20)
21 40.7070 4.20 1.58913 61.25
* 22 -30.7364 0.10
23 13.5000 2.95 1.63930 44.87
24 70.5860 1.21 1.79504 28.54
25 11.0891 (d25)
26 19.6012 3.50 1.75500 52.32
27 -400.0000 2.20 1.80518 25.42
28 50.0000 (d28)
29 0.0000 1.72 1.54437 70.51
30 0.0000 0.96 1.00000
31 0.0000 0.50 1.51680 64.19
32 0.0000 (Bf)

(Aspheric data)
[22nd page]
R κ C4 C6 C8 C10
-30.7364 +2.8898 + 2.9483 × 10 ^-5 -6.7818 × 10 ^-8 + 2.2201 × 10 ^-9 -1.9587 × 10 ^-11

(Variable interval data)
Wide-angle end state Intermediate focal length state Telephoto end state
f 7.3130 27.4787 74.1500
d5 2.8000 30.0706 47.3798
d13 24.1145 8.2545 2.5000
d20 11.9322 1.3984 0.5000
d25 5.0000 23.9224 39.3644
d28 4.6293 4.6293 4.6293
Bf 0.9922 0.9921 0.9921

(Values for conditional expressions)
fw = 7.3130
f1 = 88.9069
f2 = -10.2236
f3 = 34.7598
f3a = 45.8176
f5 = 41.1706
βat = 2.4014
βbt = −0.7191
(1) f1 / fw = 12.1574
(2) f3a / f3 = 1.3181
(3) βbt × (1−βat) = 1.0077
(4) f1 / | f2 | = 8.6963
(5) fw / f3a = 0.1596
(6) f5 / fw = 5.6298

  FIG. 9 is a diagram of various aberrations of the zoom lens according to the third example in the infinite focus state with respect to the d-line (λ = 587.6 nm), and (a) is a wide-angle end state (f = 7.31 mm). (B) shows various aberration diagrams in the intermediate focal length state (f = 27.48 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 74.15 mm).

  FIG. 10 is a lateral aberration diagram of the zoom lens according to the third example at the time of lens shift with respect to the d-line (λ = 587.6 nm), and FIG. 10A is the lateral aberration in the wide-angle end state (f = 7.31 mm). Aberration diagrams, (b) shows lateral aberration diagrams in the intermediate focal length state (f = 27.48 mm), and (c) shows lateral aberration diagrams in the telephoto end state (f = 74.15 mm).

  As is apparent from each aberration diagram, the zoom lens according to the third example has excellent imaging performance with various aberrations corrected well in each focal length state from the wide-angle end state to the telephoto end state. I understand.

[Fourth embodiment]
FIG. 11 is a diagram showing a configuration of a zoom lens according to Example 4 of the present invention.

  In FIG. 11, the first lens group G1 includes a cemented positive lens formed by bonding a negative meniscus lens L11 having a concave surface directed toward the image side and a positive meniscus lens L12 having a convex surface directed toward the object side, and an object. It is composed of a positive meniscus lens L13 having a convex surface facing the side.

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. It consists of

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a includes, in order from the object side, a cemented positive lens formed by bonding a negative meniscus lens L31 having a concave surface facing the image side and a biconvex positive lens L32. The second partial lens group G3b is composed of a cemented positive lens formed by bonding a biconvex positive lens L33 and a biconcave negative lens L34 in order from the object side. By shifting the first partial lens group G3a in a direction substantially perpendicular to the optical axis, the image on the image plane I is shifted, and image quality deterioration due to camera shake or the like is corrected.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric image side surface, a positive meniscus lens L42 having a convex surface facing the object side, and a concave surface on the image side. It is composed of a cemented negative lens that is formed by bonding with a negative meniscus lens L43 directed to it.

  The fifth lens group G5 is composed of a cemented positive lens formed by bonding a biconvex positive lens L51 and a biconcave negative lens L52.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The aperture stop S is disposed closest to the object side of the third lens group G3, and moves integrally with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T.

  In the zoom lens of this embodiment, the fifth lens group G5 is moved to the object side to perform focus adjustment (focusing) from a long-distance object to a short-distance object.

  Table 4 below provides values of specifications of the zoom lens according to the fourth example of the present invention.

(Table 4)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 7.31 to 27.50 to 86.40
F.NO = 2.70 to 3.91 to 5.43
2ω = 79.14-23.17-7.45

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 82.8560 1.70 1.84666 23.78
2 53.7263 7.38 1.65160 58.55
3 301.4766 0.10
4 55.7153 5.80 1.49782 82.52
5 219.4287 (d5)
6 54.9985 1.20 1.83481 42.71
7 10.6469 5.50
8 -33.4982 1.20 1.77250 49.60
9 23.9610 0.50
10 18.6438 4.40 1.84666 23.78
11 -27.6262 0.49
12 -20.2678 0.80 1.80440 39.58
13 142.9604 (d13)
14 0.0000 0.80 (Aperture stop S)
15 28.7946 1.96 1.80610 40.92
16 16.3971 3.20 1.49782 82.52
17 -39.8655 1.00
18 22.7205 3.20 1.48749 70.23
19 -15.2325 1.05 1.56384 60.66
20 50.0000 (d20)
21 27.1863 4.20 1.58913 61.25
* 22 -38.3195 0.10
23 16.2745 2.74 1.63930 44.87
24 49.9910 1.13 1.79504 28.54
25 11.8165 (d25)
26 21.1657 3.50 1.75500 52.32
27 -250.0000 2.20 1.80518 25.42
28 58.3737 (d28)
29 0.0000 1.72 1.54437 70.51
30 0.0000 0.96
31 0.0000 0.50 1.51680 64.19
32 0.0000 (Bf)

(Aspheric data)
[22nd page]
R κ C4 C6 C8 C10
-38.3195 +2.3115 + 2.8377 × 10 ^-5 -8.3876 × 10 ^-8 + 2.1857 × 10 ^-9 -1.9709 × 10 ^-11

(Variable interval data)
Wide-angle end state Intermediate focal length state Telephoto end state
f 7.3130 27.4968 86.4004
d5 2.8000 30.0853 48.9465
d13 26.5465 9.4764 2.5000
d20 12.3712 1.5905 0.5000
d25 5.0000 24.4219 44.7056
d28 5.0447 5.0447 5.0447
Bf 0.9990 0.9990 0.9990

(Values for conditional expressions)
fw = 7.3130
f1 = 90.3865
f2 = -10.3770
f3 = 35.5404
f3a = 46.2697
f5 = 42.9763
βat = 2.4042
βbt = -0.7799
(1) f1 / fw = 12.3597
(2) f3a / f3 = 1.3019
(3) βbt × (1−βat) = 1.0952
(4) f1 / | f2 | = 8.7103
(5) fw / f3a = 0.1581
(6) f5 / fw = 5.8767

  FIG. 12 is a diagram of various aberrations of the zoom lens according to the fourth example in the infinitely focused state with respect to the d-line (λ = 587.6 nm), and (a) is a wide-angle end state (f = 7.31 mm). (B) shows various aberration diagrams in the intermediate focal length state (f = 27.50 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 86.40 mm).

  FIG. 13 is a lateral aberration diagram during lens shift with respect to the d-line (λ = 587.6 nm) of the zoom lens according to the fourth example. FIG. 13A illustrates the lateral aberration in the wide-angle end state (f = 7.31 mm). The aberration diagram, (b) shows the lateral aberration diagram in the intermediate focal length state (f = 27.50 mm), and (c) shows the lateral aberration diagram in the telephoto end state (f = 86.40 mm).

  As is apparent from each aberration diagram, the zoom lens according to the fourth example has excellent imaging performance with various aberrations corrected well in each focal length state from the wide-angle end state to the telephoto end state. I understand.

  As an embodiment of the present invention, a zoom lens system having a five-group configuration is shown. However, a zoom lens system in which an additional lens group is added to the five groups is also an equivalent zoom lens system having the effects of the present invention. Needless to say. In addition, in the configuration within each lens group, it goes without saying that a lens group in which an additional lens is added to the configuration of the embodiment is an equivalent lens group in which the effects of the present invention are inherent. Further, the above-described embodiment is merely an example, and is not limited to the above-described configuration or shape, and can be appropriately modified and changed within the scope of the present invention.

It is a figure which shows the movement locus | trajectory of each lens group in the refractive power distribution of the zoom lens concerning each Example of this invention, and the change of the focal distance state from the wide-angle end state W to the telephoto end state T. It is a figure which shows the structure of the zoom lens concerning 1st Example of this invention. FIG. 7A is a diagram illustrating various aberrations of the zoom lens according to the first example in the infinite focus state with respect to the d-line (λ = 587.6 nm), and FIG. (B) shows various aberration diagrams in the intermediate focal length state (f = 25.90 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 74.15 mm). FIG. 6 is a lateral aberration diagram during the lens shift with respect to the d-line (λ = 587.6 nm) of the zoom lens according to the first example, and (a) is a lateral aberration diagram in the wide-angle end state (f = 7.31 mm). (B) is a lateral aberration diagram in the intermediate focal length state (f = 25.90 mm), and (c) is a lateral aberration diagram in the telephoto end state (f = 74.15 mm). It is a figure which shows the structure of the zoom lens concerning 2nd Example of this invention. FIG. 7A is a diagram illustrating various aberrations of the zoom lens according to the second example in the infinite focus state with respect to the d-line (λ = 587.6 nm), and FIG. (B) shows various aberration diagrams in the intermediate focal length state (f = 27.23 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 74.15 mm). FIG. 6A is a lateral aberration diagram at the time of lens shift with respect to the d-line (λ = 587.6 nm) of the zoom lens according to the second example, and (a) is a lateral aberration diagram in a wide angle end state (f = 7.31 mm). (B) is a lateral aberration diagram in the intermediate focal length state (f = 27.23 mm), and (c) is a lateral aberration diagram in the telephoto end state (f = 74.15 mm). It is a figure which shows the structure of the zoom lens concerning 3rd Example of this invention. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to the third example in the infinite focus state with respect to the d-line (λ = 587.6 nm), and FIG. (B) shows various aberration diagrams in the intermediate focal length state (f = 27.48 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 74.15 mm). FIG. 7A is a lateral aberration diagram during lens shift with respect to the d-line (λ = 587.6 nm) of the zoom lens according to the third example, and FIG. 9A is a lateral aberration diagram in the wide-angle end state (f = 7.31 mm). (B) is a lateral aberration diagram in the intermediate focal length state (f = 27.48 mm), and (c) is a lateral aberration diagram in the telephoto end state (f = 74.15 mm). It is a figure which shows the structure of the zoom lens concerning 4th Example of this invention. FIG. 7A is a diagram illustrating various aberrations of the zoom lens according to the fourth example in the infinite focus state with respect to the d-line (λ = 587.6 nm), and FIG. 9A illustrates various aberrations in the wide-angle end state (f = 7.31 mm). (B) shows various aberration diagrams in the intermediate focal length state (f = 27.50 mm), and (c) shows various aberration diagrams in the telephoto end state (f = 86.40 mm). FIG. 6A is a lateral aberration diagram at the time of lens shift with respect to d line (λ = 587.6 nm) of the zoom lens according to the fourth example, and FIG. (B) is a lateral aberration diagram in the intermediate focal length state (f = 27.50 mm), and (c) is a lateral aberration diagram in the telephoto end state (f = 86.40 mm).

Explanation of symbols

G1 first lens group G2 second lens group G3 third lens group G4 fourth lens group G5 fifth lens group G3a first partial lens group G3b second partial lens group FL filter group I image surface

Claims (10)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A group and a fifth lens group having a positive refractive power,
When the focal length changes from the wide-angle end state to the telephoto end state, the first lens group moves with respect to the image plane, the distance between the first lens group and the second lens group changes, and the first lens group changes. The distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group decreases, and the distance between the fourth lens group and the fifth lens group increases. And
The third lens group includes, in order from the object side, an aperture stop, a first partial lens group having a positive refractive power, and a second partial lens group having a positive refractive power, and the first partial lens group is It is possible to shift the image by shifting in a direction substantially perpendicular to the optical axis,
An image-shiftable zoom lens that satisfies the following conditions:
10.0 <f1 / fw <14.0
However,
fw: focal length of the entire zoom lens system capable of image shift in the wide-angle end state f1: focal length of the first lens group The zoom lens capable of image shifting according to claim 1.
An image-shiftable zoom lens, wherein the fifth lens group is fixed with respect to the image plane in an infinitely focused state when the focal length changes from the wide-angle end state to the telephoto end state. The zoom lens capable of image shifting according to claim 1 or 2,
The first partial lens group is a cemented lens of a meniscus negative lens having a convex surface facing the object side and a positive lens having a convex surface facing the object side,
The zoom lens capable of image shifting, wherein the second partial lens group is a cemented lens of a positive lens having a convex surface facing the object side and a biconcave negative lens. The zoom lens capable of image shifting according to any one of claims 1 to 3,
An image-shiftable zoom lens that satisfies the following conditions:
1.0 <f3a / f3 <1.5
However,
f3: focal length of the third lens group f3a: focal length of the first partial lens group The zoom lens capable of image shifting according to any one of claims 1 to 4,
An image-shiftable zoom lens that satisfies the following conditions:
0.8 <βbt × (1−βat) <1.2
However,
βat: used lateral magnification of the first partial lens group in the telephoto end state βbt: used lateral magnification in the entire lens system between the first partial lens group and the image plane in the telephoto end state The zoom lens capable of shifting an image according to any one of claims 1 to 5,
An image-shiftable zoom lens that satisfies the following conditions:
7.0 <f1 / | f2 | <11.0
However,
f2: Focal length of the second lens group The zoom lens capable of image shifting according to any one of claims 1 to 6,
An image-shiftable zoom lens that satisfies the following conditions:
0.10 <fw / f3a <0.20 The zoom lens capable of image shift according to any one of claims 1 to 7,
An image-shiftable zoom lens characterized in that the fifth lens group is moved toward the object side to perform focus adjustment from a long-distance object to a short-distance object. The zoom lens capable of image shifting according to any one of claims 1 to 8,
An image-shiftable zoom lens that satisfies the following conditions:
4.0 <f5 / fw <9.0
However,
f5: focal length of the fifth lens group The zoom lens capable of image shift according to any one of claims 1 to 9,
An image shiftable zoom lens comprising at least one aspherical lens in the fourth lens group.

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