JP2011107269A - Lens system, optical equipment, and method of manufacturing lens system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a lens system which satisfies both of internal focusing system and a decentering lens group with obtaining compactness and excellent imaging performance; optical equipment having the lens system; and a method of manufacturing the lens system. <P>SOLUTION: The lens system includes a plurality of lens groups. The lens group to an image side of the lens group closest to an object has a positive refractive power. The lens group to the image side of the lens group closest to the object has a focusing lens group Gf for focusing from an infinite distance object to a near distance object, and the decentering lens group Gs which can move to have components vertical to the optical axis, and the focusing lens group Gf is arranged to the image side of the decentering lens group Gs. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens system, an optical apparatus having the lens system, and a method for manufacturing the lens system.

  Conventionally, a lens system suitable for a digital still camera, a video camera, or the like has been proposed (see, for example, Patent Document 1).

JP-A-8-234102

  In the conventional lens system, there is a problem that the lens system becomes large in the case where the lens group closest to the object side is focused.

  The present invention has been made in view of the above-described problems, and provides a lens system that has both an in-focus method and a decentered lens group and that has a small size and high imaging performance, an optical apparatus having the lens system, and a method for manufacturing the lens system. The purpose is to do.

  In order to solve the above-described problem, the present invention includes a plurality of lens groups, and the lens group on the image side of the most object side lens group has a positive refractive power, and the image of the lens group on the most object side. The lens group on the side has a focusing lens group that focuses from an object at infinity to a near object, and a decentered lens group that can move so as to have a component in a direction perpendicular to the optical axis. The focusing lens group is disposed on the image side of the decentered lens group.

  The present invention also provides an optical apparatus comprising the lens system.

  Further, the present invention is a method of manufacturing a lens system that includes a plurality of lens groups, and the lens group closest to the image side of the lens group closest to the object side has a positive refractive power. A focusing lens group that performs focusing and an eccentric lens group that can move so as to have a component in a direction perpendicular to the optical axis are arranged in the lens group on the image side of the most object side lens group And providing a method of manufacturing a lens system, wherein the focusing lens group is disposed on the image side of the decentered lens group.

  According to the present invention, it is possible to provide a lens system that has both an in-focus method and a decentered lens group and that has a small size and high imaging performance, an optical apparatus having the lens system, and a method for manufacturing the lens system.

It is sectional drawing which shows the structure of the lens system which concerns on 1st Example. The aberration diagrams of the lens system according to Example 1 in the infinite focus state are shown, (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. FIG. 4A illustrates various aberration diagrams of the lens system according to Example 1 in a short distance in-focus state (imaging magnification: −0.01 ×), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) ) Indicates the telephoto end state. The coma aberration figure in the lens shift state (0.2 mm) of the infinity focusing state of the lens system which concerns on 1st Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal-distance state, (c ) Indicates the telephoto end state. It is sectional drawing which shows the structure of the lens system which concerns on 2nd Example. The aberration diagrams in the infinite focus state of the lens system according to Example 2 are shown, (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. FIG. 5A illustrates various aberration diagrams of the lens system according to Example 2 in a short-distance in-focus state (shooting magnification—0.01 times), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c ) Indicates the telephoto end state. The coma aberration figure in the lens shift state (0.2 mm) of the infinite focus state of the lens system which concerns on 2nd Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal distance state, (c ) Indicates the telephoto end state. It is sectional drawing which shows the structure of the lens system which concerns on 3rd Example. FIG. 5A illustrates aberrations of the lens system according to Example 3 in an infinitely focused state, where FIG. 10A illustrates a wide-angle end state, FIG. 9B illustrates an intermediate focal length state, and FIG. 9C illustrates a telephoto end state. FIG. 5A illustrates various aberration diagrams of the lens system according to Example 3 in a short-distance in-focus state (imaging magnification: 0.01 times), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c ) Indicates the telephoto end state. The coma aberration figure in the lens shift state (0.2 mm) of the infinity focusing state of the lens system which concerns on 3rd Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal distance state, (c ) Indicates the telephoto end state. It is sectional drawing which shows the structure of the lens system which concerns on 4th Example. The aberration diagrams of the lens system according to Example 4 in the infinite focus state are shown, (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. FIG. 9A illustrates various aberration diagrams of the lens system according to Example 4 in a short-distance in-focus state (shooting magnification—0.01 times), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c ) Indicates the telephoto end state. The coma aberration figure in the lens shift state (0.2 mm) of the infinite focus state of the lens system which concerns on 4th Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal distance state, (c ) Indicates the telephoto end state. It is sectional drawing which shows the structure of the lens system which concerns on 5th Example. The aberration diagrams of the lens system according to Example 5 in the infinite focus state are shown, (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. FIG. 5A illustrates various aberration diagrams of the lens system according to Example 5 in a short-distance in-focus state (imaging magnification: −0.01 ×), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c ) Indicates the telephoto end state. The coma aberration figure in the lens shift state (0.2 mm) of the infinity focusing state of the lens system which concerns on 5th Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal-distance state, (c ) Indicates the telephoto end state. It is sectional drawing which shows the structure of the lens system which concerns on 6th Example. The aberration diagrams of the lens system according to Example 6 in the infinite focus state are shown, (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. FIG. 9A illustrates various aberration diagrams of the lens system according to Example 6 in a short-distance in-focus state (imaging magnification: 0.01 ×), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c ) Indicates the telephoto end state. The coma aberration figure in the lens shift state (0.2 mm) of the infinite focus state of the lens system which concerns on 6th Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal distance state, (c ) Indicates the telephoto end state. It is sectional drawing which shows the structure of the lens system which concerns on 7th Example. The aberration diagrams of the lens system according to Example 7 in the infinite focus state are shown, (a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. The aberrational view in the short distance focusing state (imaging magnification -0.01 time) of the lens system which concerns on 7th Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal distance state, (c ) Indicates the telephoto end state. The coma aberration figure in the lens shift state (0.2 mm) of the infinite focus state of the lens system which concerns on 7th Example is shown, (a) is a wide angle end state, (b) is an intermediate | middle focal-distance state, (c ) Indicates the telephoto end state. It is sectional drawing which shows the structure of the lens system which concerns on 8th Example. FIG. 10 shows various aberration diagrams of the lens system according to Example 8 in the infinite focus state. FIG. 10 shows various aberration diagrams of the lens system according to Example 8 in a short-distance in-focus state (imaging magnification: -0.01 times). The coma aberration figure in the lens shift state (0.2 mm) of the infinite focus state of the lens system which concerns on 8th Example is shown. It is a figure which shows the structure of the camera provided with the lens system which concerns on 1st Example. It is a figure which shows the manufacturing method of the lens system of this application.

  Hereinafter, a lens system according to an embodiment of the present application will be described.

  The lens system according to the present embodiment includes a plurality of lens groups, the lens group on the image side of the most object side lens group has a positive refractive power, and the lens on the image side of the most object side lens group. The group includes a focusing lens group that focuses from an object at infinity to a near object, and an eccentric lens group that can move so as to have a component in a direction perpendicular to the optical axis. The lens group is arranged on the image side of the decentered lens group. The decentering lens group refers to a shift lens group or a tilt lens group.

  By placing the focusing lens group on the image side of the decentered lens group, coma aberration and field curvature degradation caused by decentering of the decentered lens group can be improved in the focusing lens group from infinity to close-up shooting conditions. It can be mitigated.

  In the lens system according to the present embodiment, the distance between the most object-side lens unit and the most object-side lens unit on the image side changes during zooming from the wide-angle end state to the telephoto end state. It is desirable that the lens group on the image side of the lens group closest to the object side moves to the object side.

  The lens group on the image side of the most object side lens group has an action of enlarging the image of the subject, and as it goes from the wide-angle end state to the telephoto end state, the most object side lens group and the most object side lens group By changing the distance from the lens group on the image side, it is possible to increase the enlargement ratio and change the focal length.

  In the lens system according to the present embodiment, it is desirable that the lens unit closest to the object side has a negative refractive power.

  By setting the lens unit closest to the object side to have a negative refractive power, it is possible to correct the fluctuation of the image plane due to zooming.

  In the lens system according to the present embodiment, it is desirable that the most object side lens unit and the lens unit located on the image side of the most object side lens unit are adjacent to each other.

  By adjoining the most object-side lens group and the lens group on the image side of the most object-side lens group, it is possible to suppress coma aberration and field curvature degradation during zooming.

  In the lens system according to this embodiment, it is desirable that an aperture stop be disposed between the focusing lens group and the decentering lens group.

  In order to minimize the performance degradation during lens shift, the lens group capable of image shift is designed to shift the lens with a lens group close to the stop where the off-axis light beam passes near the optical axis during zooming. It is possible to maintain good imaging performance. Further, by disposing the focusing lens group near the aperture stop, it is possible to suppress image plane fluctuations during focusing from infinity to the closest distance.

  In addition, the lens system according to the present embodiment desirably has an auxiliary lens group on at least one of the object side and the image side of the decentered lens group.

  By arranging the auxiliary lens group, it is possible to suppress the occurrence of eccentric coma during the image stabilization at the time of lens shift and to alleviate the deterioration of the field curvature.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (1).
(1) -11.00 <fa / fs <11.00
Here, fa is the focal length of the auxiliary lens group, and fs is the focal length of the eccentric lens group.

  Conditional expression (1) is a conditional expression for defining an appropriate range for the focal length ratio of the auxiliary lens group and the decentered lens group.

  If the upper limit of conditional expression (1) is exceeded, the refractive power of the decentered lens group becomes strong, and position control in the direction perpendicular to the optical axis of the decentered lens group becomes difficult. As a result, it is difficult to correct decentration coma and coma aberration, which is not preferable.

  On the other hand, if the lower limit of conditional expression (1) is not reached, the refractive power of the decentered lens group becomes weak, and a larger amount of lens shift is required to obtain a desired image shift amount. . Further, the correction of coma aberration and field curvature is insufficient, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (1) to 9.22. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (1) to 7.35. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (1) to 5.48.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (1) to −9.18. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (1) to −7.35. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (1) to −5.48.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (2).
(2) 0.05 <| f / ff | <0.65
Here, f is the focal length of the entire lens system, and ff is the focal length of the focusing lens group.

  Conditional expression (2) is a conditional expression for defining an appropriate range for the ratio of the focal length of the entire lens system to the focal length of the focusing lens group.

  When the upper limit of conditional expression (2) is exceeded, the refractive power of the focusing lens group becomes strong, and position control on the optical axis of the focusing lens group becomes difficult. In addition, the field curvature and coma change during close-up shooting from infinity increase, which is not preferable.

  On the other hand, if the lower limit value of conditional expression (2) is not reached, the refractive power of the focusing lens group becomes weak, and the amount of movement of the focusing lens group becomes very large. Further, the correction of coma aberration and field curvature is insufficient, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.60. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (2) to 0.54. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (2) to 0.48.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.09. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.12. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.16.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (3).
(3) 0.05 <| fγ | <2.75
However, fγ is an image plane movement coefficient of the focusing lens group (ratio of the moving amount of the image plane to the moving amount of the focusing lens group).

  Conditional expression (3) is a conditional expression for defining an appropriate range for the image plane movement coefficient of the focusing lens group.

  When the upper limit of conditional expression (3) is exceeded, the refractive power of the focusing lens group becomes weak, and position control on the optical axis of the focusing lens group becomes difficult. Further, the correction of coma aberration and field curvature is insufficient, which is not preferable.

  On the other hand, when the lower limit value of conditional expression (3) is not reached, the refractive power of the focusing lens group becomes strong, and spherical aberration and coma aberration occur in the focusing lens group alone. Furthermore, the performance degradation during close-up shooting becomes large, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (3) to 2.55. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (3) to 2.30. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (3) to 2.00.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.15. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (3) to 0.25. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (3) to 0.45.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (4).
(4) 0.05 <| fw / ff | <0.65
Here, fw is the focal length of the entire lens system in the wide-angle end state, and ff is the focal length of the focusing lens group.

  Conditional expression (4) is a conditional expression for defining an appropriate range for the ratio of the focal length of the entire lens system to the focal length of the focusing lens group in the wide-angle end state.

  When the upper limit of conditional expression (4) is exceeded, the refractive power of the focusing lens group becomes strong, and position control on the optical axis of the focusing lens group becomes difficult. In addition, the field curvature and coma change during close-up shooting from infinity increase, which is not preferable.

  On the other hand, if the lower limit value of conditional expression (4) is not reached, the refractive power of the focusing lens group becomes weak, and a large amount of movement of the focusing lens group is required. Further, the correction of coma aberration and field curvature is insufficient, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.60. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (4) to 0.54. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (4) to 0.48.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.09. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (4) to 0.12. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (4) to 0.16.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (5).
(5) 0.05 <| fγw | <2.75
However, fγw is an image plane movement coefficient (ratio of the moving amount of the image plane to the moving amount of the focusing lens group) in the wide-angle end state of the focusing lens group.

  Conditional expression (5) is a conditional expression for defining an appropriate range for the image plane movement coefficient in the wide-angle end state of the focusing lens group.

  When the upper limit of conditional expression (5) is exceeded, the refractive power of the focusing lens group becomes weak, and position control on the optical axis of the focusing lens group becomes difficult. Further, the correction of coma aberration and field curvature is insufficient, which is not preferable.

  On the other hand, when the lower limit of conditional expression (5) is not reached, the refractive power of the focusing lens group becomes strong, and spherical aberration and coma aberration occur in the focusing lens group alone. Furthermore, the performance degradation during close-up shooting becomes large, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (5) to 2.55. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (5) to 2.30. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (5) to 2.00.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.15. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (5) to 0.25. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (5) to 0.45.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (6).
(6) -4.00 <ff / fs <4.00
Here, ff is the focal length of the focusing lens group, and fs is the focal length of the eccentric lens group.

  Conditional expression (6) is a conditional expression for defining an appropriate range for the focal length ratio between the focusing lens group and the decentering lens group.

  When the upper limit of conditional expression (6) is exceeded, the refractive power of the focusing lens group becomes weak, and position control on the optical axis of the focusing lens group becomes difficult. Further, the correction of coma aberration and field curvature is insufficient, which is not preferable. Further, the refractive power of the decentered lens group becomes strong, and position control in the direction perpendicular to the optical axis of the decentered lens group becomes difficult. As a result, it is difficult to correct decentration coma and coma aberration, which is not preferable.

  Conversely, when the lower limit of conditional expression (6) is not reached, the refractive power of the focusing lens group becomes strong, and spherical aberration and coma aberration occur in the focusing lens group alone. Furthermore, the performance degradation during close-up shooting becomes large, which is not preferable. Further, the refractive power of the decentered lens group becomes weak, and a larger amount of lens shift is required to obtain a desired image shift amount. Further, the correction of coma aberration and field curvature is insufficient, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (6) to 3.32. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (6) to 2.66. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (6) to 2.00.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (6) to −3.34. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (6) to −2.67. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (6) to −2.00.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (7).
(7) 0.00 <(d1-2) / ft <1.50
However, d1-2 is the air space on the optical axis from the lens surface on the image side of the lens closest to the object side in the entire lens system to the lens surface on the object side of the lens immediately after that, and ft is the total lens distance in the telephoto end state. The focal length of the system.

  Conditional expression (7) is a conditional expression regarding the air space on the optical axis from the lens surface on the image side of the lens closest to the object side in the entire lens system to the lens surface on the object side of the lens immediately after that.

  When the upper limit value of conditional expression (7) is exceeded, the air space on the optical axis from the lens surface on the image side of the lens closest to the object side in the entire lens system to the lens surface on the object side of the lens immediately thereafter increases. End up. As a result, the lens unit closest to the object side in the entire lens system becomes thick. As a result, it is difficult to sufficiently correct coma and curvature of field, which is not preferable.

  On the other hand, if the lower limit value of conditional expression (7) is not reached, the refractive power of the lens closest to the object side becomes weak, and correction of curvature of field and curvature of field due to zooming becomes insufficient, which is not preferable. .

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (7) to 1.30. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (7) to 1.15. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (7) to 1.00.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (7) to 0.04. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (7) to 0.09. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (7) to 0.13.

  In the lens system according to this embodiment, it is desirable that the decentered lens group has an aspherical surface.

  With this configuration, it is possible to satisfactorily correct spherical aberration and coma generated by the decentered lens unit alone, and particularly to reduce performance degradation of coma due to decentration.

  In addition, the lens system according to the present embodiment includes a blur detection system and a driving unit that detect a blur of the lens system in order to prevent a shooting failure due to an image blur caused by a camera shake or the like that is likely to occur in a high-magnification zoom lens. Can be combined with the lens system, and all or a part of one lens group among the lens groups constituting the lens system can be decentered as an eccentric lens group. In other words, it is possible to drive the decentered lens group by the driving means and shift the image so as to correct image blur (fluctuation in image plane position) caused by the blur of the lens system detected by the blur detection system. . As described above, the lens system according to the present embodiment can function as a so-called vibration-proof optical system.

(Example)
Hereinafter, each example according to the present embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view showing a configuration of a lens system according to the first example.

  As shown in FIG. 1, the lens system according to the first example includes a first lens group G1 having negative refractive power and a second lens group G2 having positive refractive power in order from the object side along the optical axis. And the first lens group G1 and the second lens group so that the air gap between the first lens group G1 and the second lens group G2 is reduced upon zooming from the wide-angle end state W to the telephoto end state T. G2 moves.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. ing. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens having an aspheric surface on the image plane I side.

  The second lens group G2 includes, in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex lens L22, an aperture stop S, a biconvex lens L23, and the object side. A cemented positive lens with a negative meniscus lens L24 having a concave surface facing the lens, a negative meniscus lens L25 with a convex surface facing the object side, and a cemented positive lens with a negative meniscus lens L26 having a convex surface facing the object side and a biconvex lens L27. It is composed of The negative meniscus lens L21 located closest to the object side in the second lens group G2 is an aspheric lens having an aspheric surface on the object side. The biconvex lens L27 located closest to the image plane I in the second lens group G2 is an aspherical lens in which an aspheric surface is formed on the image plane I side.

  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 same applies to the following embodiments).

  The aperture stop S arranged in the second lens group G2 moves together with the second lens group G2 toward the object side during zooming from the wide-angle end state W to the telephoto end state T.

  The cemented positive lens of the biconvex lens L23 and the negative meniscus lens L24 is a focusing lens group Gf. By moving the focusing lens group Gf to the object side, focusing from an object at infinity to a near object is performed.

  The cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a decentered lens group Gs, and camera shake correction (anti-vibration) is performed by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The negative meniscus lens L25 and the cemented positive lens of the negative meniscus lens L26 and the biconvex lens L27 are the auxiliary lens group Ga having negative refractive power.

  Table 1 below lists specifications of the lens system according to the first example.

  In (surface data) in the table, the object surface is the object surface, the surface number is the surface number from the object side, r is the radius of curvature, d is the surface spacing, and nd is the refraction at the d-line (wavelength λ = 587.6 nm). The ratio, νd represents the Abbe number in the d-line (wavelength λ = 587.6 nm), (variable) represents the variable surface interval, (diaphragm) represents the aperture stop S, and the image plane represents the image plane I. Note that the description of the refractive index nd of air = 1.000 is omitted. Further, “∞” in the radius of curvature r column indicates a plane.

In (Aspheric data), the aspheric surface is expressed by the following equation.
X (y) = (y ² / r) / [1+ [1-κ (y ² / r ² )] ^1/2 ]
+ A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ + A10 × y ¹⁰
Here, the height in the direction perpendicular to the optical axis is y, and the amount of displacement in the optical axis direction at the height y (the distance along the optical axis from the tangential plane of each aspheric surface to each aspheric surface) is X ( y) Let r be the radius of curvature (paraxial radius of curvature) of the reference sphere, κ be the conic coefficient, and An be the n-th aspherical coefficient. “En” represents “× 10 ⁻ⁿ ”, for example “1.234E-05” represents “1.234 × 10 ⁻⁵ ”. Each aspherical surface is indicated with “*” on the right side of the surface number in (surface data).

  (Various data), the zoom ratio is the zoom ratio of the lens system, W is the wide angle end state, M is the intermediate focal length state, T is the telephoto end state, f is the focal length, FNO is the F number, 2ω is the angle of view ( (Unit: “°”), Y is the image height, TL is the entire length of the lens system, Bf is the back focus, and di is the variable surface interval value at surface number i.

  In (focusing lens group movement amount data), W is the wide-angle end state, M is the intermediate focal length state, T is the telephoto end state, f is the focal length, and ΔFx is the movement amount of the focusing lens group during close-up shooting. (Movement to the object side is positive).

  (Zoom lens group data) indicates the start surface number of each lens group and the focal length of the lens group.

  (Conditional expression corresponding value) indicates the corresponding value of each conditional expression.

  In all the following specification values, “mm” is generally used as the focal length f, radius of curvature r, surface interval d and other lengths, etc. unless otherwise specified, but the optical system is proportional. Even if it is enlarged or proportionally reduced, the same optical performance can be obtained. Further, the unit is not limited to “mm”, and other appropriate units may be used. Further, the explanation of these symbols is the same in the other embodiments, and the explanation is omitted.

(Table 1)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 18.6779 1.30 1.85135 40.10
2 * 7.8525 7.25
3 -94.6821 1.00 1.83481 42.72
4 34.1506 0.31
5 18.6651 2.51 1.86074 23.06
6 78.9142 (variable)

7 * 18.1125 1.30 1.83441 37.28
8 12.2772 1.76 1.59319 67.87
9 -2494.0282 3.99
10 (Aperture) ∞ 1.00
11 23.3375 1.67 1.74400 44.78
12 -19.5626 1.00 1.67270 32.11
13 -219.6865 2.59
14 106.9379 1.53 1.80486 24.73
15 28.0039 1.36
16 352.0524 0.83 1.79952 42.24
17 10.0128 2.17 1.69350 53.20
18 * -38.1016 (Bf)
Image plane ∞

(Aspheric data)
Second side κ = 0.6460
A4 = 1.2719E-05
A6 = 5.3251E-07
A8 = -4.7392E-09
A10 = 4.5963E-11
7th surface κ = -1.0893
A4 = 3.0467E-05
A6 = 9.8555E-08
A8 = -1.0556E-08
A10 = 2.2926E-10
18th surface κ = 1.0000
A4 = 6.6102E-05
A6 = 5.9125E-08
A8 = 3.8159E-08
A10 = -1.1681E-09

(Various data)
Zoom ratio 2.825
W M T
f = 10.30 17.30 29.10
FNO = 3.31 4.22 5.78
2ω = 77.59 49.65 30.52
Y = 7.96 7.96 7.96
TL = 73.80 67.53 72.19
Bf = 18.7255 26.4381 39.4394

d6 23.5020 9.5180 1.1743

(Focus lens group movement data)
W M T
f = 10.3000 17.3000 29.0999
ΔFx = 0.0669 0.0967 0.1445

(Zoom lens group data)
Group Start surface Focal length 1 1 -17.744
2 7 19.8044

(Values for conditional expressions)
fw = 10.3000
ft = 29.0999
ff = 26.0978
fs = 36.6504
fa = −98.3425
d1-2 = 7.2500
fγw = 1.5400
(1) fa / fs = −2.6833
(4) | fw / ff | = 0.3947
(5) | fγw | = 1.5400
(6) ff / fs = 0.7121
(7) (d1-2) /ft=0.2491

  2A and 2B are graphs showing various aberrations of the lens system according to Example 1 in an infinitely focused state, where FIG. 2A is a wide-angle end state, FIG. 2B is an intermediate focal length state, and FIG. 2C is a telephoto end state. Respectively.

  FIGS. 3A and 3B are graphs showing various aberrations of the lens system according to Example 1 in a short-distance in-focus state (shooting magnification—0.01 times), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  4A and 4B are coma aberration diagrams in the lens shift state (0.2 mm) in the infinitely focused state of the lens system according to Example 1. FIG. 4A is a wide-angle end state, and FIG. 4B is an intermediate focal length. The state (c) shows the telephoto end state.

  In each aberration diagram, FNO is an F number, A is a half angle of view (unit: “°”), NA is a numerical aperture, and H0 is an object height (unit: “mm”). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane.

  In the following examples, the same symbols are used, and the following description is omitted.

  From each aberration diagram, it can be seen that the lens system according to the first example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Second embodiment)
FIG. 5 is a cross-sectional view showing a configuration of a lens system according to the second example.

  As shown in FIG. 5, the lens system according to the second example includes a first lens group G1 having negative refractive power and a second lens group G2 having positive refractive power in order from the object side along the optical axis. And the first lens group G1 and the second lens group so that the air gap between the first lens group G1 and the second lens group G2 is reduced upon zooming from the wide-angle end state W to the telephoto end state T. G2 moves.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface directed toward the object side, a biconcave lens L12, a positive meniscus lens L13 having a convex surface directed toward the object side, and an object side And a positive meniscus lens L14 having a convex surface. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens having an aspheric surface on the image plane I side.

  The second lens group G2 includes, in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side, and an aperture stop S A cemented positive lens of a biconvex lens L23 and a negative meniscus lens L24 having a concave surface facing the object side, a positive meniscus lens L25 having a convex surface facing the object side, and a cemented negative lens of a biconcave lens L26 and a biconvex lens L27. It is composed of The negative meniscus lens L21 located closest to the object side in the second lens group G2 is an aspheric lens having an aspheric surface on the object side. The positive meniscus lens L25 located on the image plane I side of the decentered lens group Gs of the second lens group G2 is an aspheric lens having an aspheric surface on the object side. The biconvex lens L27 located closest to the image plane I in the second lens group G2 is an aspherical lens in which an aspheric surface is formed on the image plane I side.

  The aperture stop S arranged in the second lens group G2 moves together with the second lens group G2 toward the object side during zooming from the wide-angle end state W to the telephoto end state T.

  The positive meniscus lens L25 is a focusing lens group Gf, and the focusing lens group Gf is moved to the object side, thereby focusing from an infinite object to a short distance object.

  The cemented positive lens of the biconvex lens L23 and the negative meniscus lens L24 is a decentered lens group Gs, and camera shake correction (anti-vibration) is performed by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The cemented positive lens of the negative meniscus lens L21 and the positive meniscus lens L22 is the auxiliary lens group Ga.

  Table 2 below lists specifications of the lens system according to the second example.

(Table 2)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 16.2784 1.30 1.85135 40.10
2 * 8.9447 5.30
3 -301.3986 1.00 1.88300 40.76
4 12.6615 1.06
5 18.9306 1.56 1.76346 26.38
6 27.0707 1.36
7 18.2904 2.18 1.86074 23.06
8 58.5517 (variable)

9 * 16.7318 1.39 1.85135 40.10
10 11.1081 1.81 1.58090 57.73
11 676.4968 4.01
12 (Aperture) ∞ 1.00
13 134.3575 1.83 1.75197 47.49
14 -10.0350 1.00 1.83781 31.56
15 -34.0385 1.80
16 * 13.9946 1.35 1.77377 47.17
17 24.7571 2.13
18 -54.0166 0.80 1.89370 35.17
19 9.5527 1.80 1.73077 40.50
20 * -53.9739 (Bf)
Image plane ∞

(Aspheric data)
Second side κ = 0.1601
A4 = 9.1340E-05
A6 = 4.5205E-07
A8 = 5.5818E-09
A10 = -2.4977E-11
9th surface κ = -3.5386
A4 = 1.0402E-04
A6 = -8.0989E-07
A8 = 1.5095E-08
A10 = -1.1446E-10
16th surface κ = -0.0568
A4 = 1.5624E-04
A6 = 1.5318E-06
A8 = 1.2547E-08
A10 = 0.0000E + 00
20th surface κ = 1.0000
A4 = 1.9868E-04
A6 = 1.8409E-06
A8 = 9.4693E-08
A10 = -1.4396E-09

(Various data)
Zoom ratio 2.825
W M T
f = 10.30 17.30 29.10
FNO = 3.51 4.14 5.77
2ω = 78.05 49.64 30.55
Y = 7.96 7.96 7.96
TL = 74.56 70.81 77.93
Bf = 20.7334 29.3225 43.8013

d8 21.1546 8.8150 1.4524

(Focus lens group movement data)
W M T
f = 10.3000 17.3001 29.1002
ΔFx = 0.0672 0.0808 0.0889

(Zoom lens group data)
Group Start surface Focal length 1 1-16.0000
2 9 19.6321

(Values for conditional expressions)
fw = 10.3000
ft = 29.1002
ff = 39.4493
fs = 49.2923
fa = 37.5001
d1-2 = 5.2957
fγw = 1.5310
(1) fa / fs = 0.7608
(4) | fw / ff | = 0.2611
(5) | fγw | = 1.5310
(6) ff / fs = 0.003
(7) (d1-2) /ft=0.1820

  6A and 6B are graphs showing various aberrations of the lens system according to Example 2 in an infinitely focused state, where FIG. 6A is a wide-angle end state, FIG. 6B is an intermediate focal length state, and FIG. 6C is a telephoto end state. Respectively.

  FIG. 7 is a diagram illustrating various aberrations of the lens system according to Example 2 in a short distance in-focus state (imaging magnification: −0.01 times), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  8A and 8B show coma aberration diagrams in the lens shift state (0.2 mm) in the infinitely focused state of the lens system according to Example 2. FIG. 8A is a wide-angle end state, and FIG. 8B is an intermediate focal length. The state (c) shows the telephoto end state.

  From each aberration diagram, it can be seen that the lens system according to the second example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Third embodiment)
FIG. 9 is a cross-sectional view showing a configuration of a lens system according to the third example.

  As shown in FIG. 9, the lens system according to the third example includes, in order from the object side along the optical axis, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. And the first lens group G1 and the second lens group so that the air gap between the first lens group G1 and the second lens group G2 is reduced upon zooming from the wide-angle end state W to the telephoto end state T. G2 moves.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. It is composed of a positive meniscus lens L13 and a positive meniscus lens L14 having a convex surface facing the object side. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens having an aspheric surface on the image plane I side.

  The second lens group G2 includes, in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side, A positive meniscus lens L23 having a convex surface, an aperture stop S, a cemented positive lens having a biconvex lens L24 and a negative meniscus lens L25 having a concave surface facing the object side, and a cemented negative lens having a biconcave lens L26 and a biconvex lens L27 It is composed of The negative meniscus lens L21 located closest to the object side in the second lens group G2 is an aspheric lens having an aspheric surface on the object side. The positive meniscus lens L23 located on the object side of the aperture stop S of the second lens group G2 is an aspheric lens having an aspheric surface on the object side. The biconvex lens L27 located closest to the image plane I in the second lens group G2 is an aspherical lens in which an aspheric surface is formed on the image plane I side.

  The aperture stop S arranged in the second lens group G2 moves together with the second lens group G2 toward the object side during zooming from the wide-angle end state W to the telephoto end state T.

  The cemented negative lens of the biconcave lens L26 and the biconvex lens L27 is a focusing lens group Gf. By moving the focusing lens group Gf to the image plane I side, focusing from an infinite object to a short-distance object is performed. .

  The cemented positive lens of the biconvex lens L24 and the negative meniscus lens L25 is a decentered lens group Gs, and camera shake correction (anti-vibration) is performed by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The positive meniscus lens L23 is the auxiliary lens group Ga.

  Table 3 below lists specifications of the lens system according to the third example.

(Table 3)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 18.4021 1.30 1.85135 40.10
2 * 9.4660 5.19
3 106.6621 1.00 1.88300 40.76
4 12.4920 1.75
5 18.3528 1.77 1.84666 23.78
6 28.9480 0.65
7 17.1399 2.08 1.80809 22.79
8 32.7787 (variable)

9 * 15.0062 0.80 1.83441 37.28
10 9.9310 1.70 1.74100 52.67
11 36.5917 4.24
12 * 20.2806 1.24 1.58913 61.25
13 519.9944 0.80
14 (Aperture) ∞ 1.00
15 33.1718 2.09 1.61720 54.01
16 -13.7000 1.00 1.74077 27.78
17 -47.2996 0.81
18 ∞ 1.00
19 -12.0144 0.80 1.83400 37.16
20 10.7146 3.37 1.73077 40.50
21 * -14.3627 (Bf)
Image plane ∞

(Aspheric data)
Second side κ = -0.8688
A4 = 2.2426E-04
A6 = -1.1858E-07
A8 = 2.0865E-09
A10 = 0.0000E + 00
9th surface κ = 1.5382
A4 = -4.3414E-05
A6 = 1.8507E-08
A8 = -3.1873E-08
A10 = 9.2225E-10
12th surface κ = 1.0000
A4 = 6.9511E-05
A6 = 8.0932E-07
A8 = -2.7525E-09
A10 = 0.0000E + 00
21st surface κ = 1.0000
A4 = 7.5377E-05
A6 = 6.6313E-07
A8 = 0.0000E + 00
A10 = 0.0000E + 00

(Various data)
Zoom ratio 2.825
W M T
f = 10.30 17.30 29.10
FNO = 3.57 4.27 5.80
2ω = 77.45 49.72 30.58
Y = 7.96 7.96 7.96
TL = 74.59 69.93 76.27
Bf = 19.7396 28.1183 42.2423

d8 22.2705 9.2305 1.4500

(Focus lens group movement data)
W M T
f = 10.3000 17.3001 29.1002
ΔFx = -0.0718 -0.0883 -0.0984

(Zoom lens group data)
Group Start surface Focal length 1 1-16.6530
2 9 19.9329

(Values for conditional expressions)
fw = 10.3000
ft = 29.0999
ff = −52.4471
fs = 40.0000
fa = 35.7888
d1-2 = 5.1881
fγw = −1.4369
(1) fa / fs = 0.8947
(4) | fw / ff | = 0.1964
(5) | fγw | = 1.4369
(6) ff / fs = −1.3112
(7) (d1-2) /ft=0.1783

  FIGS. 10A and 10B are graphs showing various aberrations of the lens system according to Example 3 in an infinitely focused state, where FIG. 10A is a wide-angle end state, FIG. 10B is an intermediate focal length state, and FIG. 10C is a telephoto end state. Respectively.

  FIG. 11 is a diagram illustrating various aberrations of the lens system according to Example 3 in a short distance in-focus state (imaging magnification: -0.01 times), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  12A and 12B are coma aberration diagrams in the lens shift state (0.2 mm) in the infinitely focused state of the lens system according to Example 3, wherein FIG. 12A is a wide-angle end state, and FIG. 12B is an intermediate focal length. The state (c) shows the telephoto end state.

  From each aberration diagram, it can be seen that the lens system according to Example 3 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Fourth embodiment)
FIG. 13 is a cross-sectional view showing a configuration of a lens system according to the fourth example.

  As shown in FIG. 13, the lens system according to the fourth example includes, in order from the object side along the optical axis, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. And the first lens group G1 and the second lens group so that the air gap between the first lens group G1 and the second lens group G2 is reduced upon zooming from the wide-angle end state W to the telephoto end state T. G2 moves.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. ing. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens in which aspheric surfaces are formed on both surfaces. The biconcave lens L12 of the first lens group G1 is an aspheric lens in which an aspheric surface is formed on the image plane I side.

  The second lens group G2 includes, in order from the object side along the optical axis, a positive meniscus lens L21 having a convex surface facing the object side, an aperture stop S, a biconvex lens L22, and a negative meniscus lens L23 having a concave surface facing the object side. A cemented positive lens, a cemented positive lens of a negative meniscus lens L24 having a convex surface facing the object side and a biconvex lens L25, a positive meniscus lens L26 having a convex surface facing the image surface I, and a convex surface facing the image surface I. And a negative meniscus lens L27. The negative meniscus lens L27 located closest to the image plane I in the second lens group G2 is an aspheric lens having an aspheric surface formed on the image plane I side.

  The aperture stop S arranged in the second lens group G2 moves together with the second lens group G2 toward the object side during zooming from the wide-angle end state W to the telephoto end state T.

  The cemented positive lens of the negative meniscus lens L24 and the biconvex lens L25 is a focusing lens group Gf. By moving the focusing lens group Gf to the object side, focusing from an object at infinity to a near object is performed.

  The positive meniscus lens L21 is a decentered lens group Gs, and performs camera shake correction (anti-vibration) by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The positive meniscus lens L26 and the negative meniscus lens L27 are an auxiliary lens group Ga having a positive refractive power.

  Table 4 below lists specifications of the lens system according to the fourth example.

(Table 4)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 * 65.6582 1.80 1.76802 49.23
2 * 11.1606 10.60
3 -41.8065 3.20 1.76802 49.23
4 * 17.5136 3.80
5 14.4408 2.30 1.92286 20.88
6 23.0940 (variable)

7 13.2190 1.50 1.75500 52.32
8 37.9290 1.60
9 (Aperture) ∞ 1.50
10 21.6826 6.50 1.49782 82.56
11 -9.3713 1.00 1.88300 40.77
12 -50.0183 1.42
13 11.9486 1.20 1.90366 31.31
14 7.9899 2.50 1.49782 82.56
15 -409.7597 1.25
16 -5817.7134 1.80 1.49782 82.56
17 -17.3100 0.40
18 -13.7854 1.20 1.76802 49.23
19 * -21.3255 (Bf)
Image plane ∞

(Aspheric data)
First side κ = 11.2695
A4 = 6.5208E-08
A6 = 4.5111E-09
A8 = 0.0000E + 00
A10 = 0.0000E + 00
Second side κ = -0.6591
A4 = 0.0000E + 00
A6 = 0.0000E + 00
A8 = 0.0000E + 00
A10 = 0.0000E + 00
4th surface κ = 2.7380
A4 = 1.5432E-04
A6 = 3.8186E-07
A8 = 0.0000E + 00
A10 = 0.0000E + 00
19th surface κ = -21.6774
A4 = -1.3542E-04
A6 = 5.0739E-06
A8 = -6.2280E-08
A10 = 0.0000E + 00

(Various data)
Zoom ratio 1.828
W M T
f = 6.90 9.50 12.61
FNO = 3.62 4.52 5.77
2ω = 98.83 79.61 63.97
Y = 7.96 7.96 7.96
TL = 70.23 68.58 69.98
Bf = 14.6644 19.2561 24.7483

d6 11.9986 5.7487 1.6581

(Focus lens group movement data)
W M T
f = 6.9000 9.5000 12.6100
ΔFx = 0.1039 0.1452 0.2194

(Zoom lens group data)
Group Start surface Focal length 1 1 -9.4458
2 7 16.6813

(Values for conditional expressions)
fw = 6.9000
ft = 12.6100
ff = 35.2637
fs = 26.1912
fa = 101.5495
d1-2 = 10.6000
fγw = 0.6637
(1) fa / fs = 3.88772
(4) | fw / ff | = 0.1957
(5) | fγw | = 0.6637
(6) ff / fs = 1.3464
(7) (d1-2) /ft=0.8406

  FIGS. 14A and 14B show various aberration diagrams of the lens system according to Example 4 in an infinitely focused state, where FIG. 14A is a wide-angle end state, FIG. 14B is an intermediate focal length state, and FIG. 14C is a telephoto end state. Respectively.

  FIGS. 15A and 15B are graphs showing various aberrations of the lens system according to Example 4 in a short-distance in-focus state (shooting magnification—0.01 times), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  16A and 16B are coma aberration diagrams in the lens shift state (0.2 mm) in the infinitely focused state of the lens system according to Example 4, wherein FIG. 16A is a wide-angle end state, and FIG. 16B is an intermediate focal length. The state (c) shows the telephoto end state.

  From each aberration diagram, it can be seen that the lens system according to the fourth example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(5th Example)
FIG. 17 is a sectional view showing the structure of a lens system according to the fifth example.

  As shown in FIG. 17, the lens system according to Example 5 includes, in order from the object side along the optical axis, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. And the first lens group G1 and the second lens group so that the air gap between the first lens group G1 and the second lens group G2 is reduced upon zooming from the wide-angle end state W to the telephoto end state T. G2 moves.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. It comprises a positive meniscus lens L13. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens having an aspheric surface on the image plane I side.

  The second lens group G2 includes, in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L21 having a convex surface directed toward the object side and a biconvex lens L22, and a positive meniscus lens L23 having a convex surface directed toward the object side. And an aperture stop S, a biconcave lens L24, a cemented negative lens of a biconvex lens L25 and a biconcave lens L26, and a biconvex lens L27. The biconcave lens L24 of the second lens group G2 is an aspheric lens in which an aspheric surface is formed on the image plane I side. The biconvex lens L27 located closest to the image plane I in the second lens group G2 is an aspherical lens in which an aspheric surface is formed on the image plane I side.

  The aperture stop S arranged in the second lens group G2 moves together with the second lens group G2 toward the object side during zooming from the wide-angle end state W to the telephoto end state T.

  The positive meniscus lens L23 is a focusing lens group Gf, and the focusing lens group Gf is moved to the object side, thereby focusing from an infinite object to a short distance object.

  The cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a decentered lens group Gs, and camera shake correction (anti-vibration) is performed by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The biconcave lens L24, the cemented negative lens of the biconvex lens L25 and the biconcave lens L26, and the biconvex lens L27 are an auxiliary lens group Ga having negative refractive power.

  Table 5 below lists specifications of the lens system according to Example 5.

(Table 5)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 25.0000 1.80 1.77377 47.17
2 * 8.2000 5.44
3 195.9606 0.80 1.75500 52.32
4 27.4972 1.32
5 16.4792 2.39 1.84666 23.78
6 33.0474 (variable)

7 48.1225 0.80 1.80810 22.76
8 29.9061 1.89 1.65160 58.55
9 -48.2389 2.96
10 9.6847 1.93 1.60300 65.44
11 26.0017 1.00
12 (Aperture) ∞ 1.30
13 -34215.1520 0.80 1.82080 42.71
14 * 16.7358 1.76
15 20.3058 1.72 1.49700 81.54
16 -90.6802 0.80 1.83400 37.16
17 17.5527 0.44
18 12.3817 2.16 1.66910 55.42
19 * -74.1839 (Bf)
Image plane ∞

(Aspheric data)
Second side κ = 0.6129
A4 = 1.9233E-05
A6 = 1.4470E-07
A8 = 1.3914E-09
A10 = 1.5950E-12
14th surface κ = 0.1365
A4 = -3.4023E-05
A6 = 1.6026E-06
A8 = -2.1064E-07
A10 = 7.1553E-09
19th surface κ = -8.5088
A4 = 2.4559E-04
A6 = 2.7667E-06
A8 = -3.1696E-08
A10 = 4.6513E-10

(Various data)
Zoom ratio 2.825
W M T
f = 10.30 18.75 29.10
FNO = 3.64 4.59 5.86
2ω = 78.83 46.51 30.69
Y = 7.96 7.96 7.96
TL = 73.78 67.23 71.78
Bf = 20.0062 29.3544 40.8045

d6 23.7984 7.8948 1.0000

(Focus lens group movement data)
W M T
f = 10.3000 18.7500 29.1000
ΔFx = 0.0603 0.0996 0.1542

(Zoom lens group data)
Group Start surface Focal length 1 1-18.1260
2 7 20.0528

(Values for conditional expressions)
fw = 10.3000
ft = 29.1000
ff = 24.5050
fs = 40.2798
fa = -149.0129
d1-2 = 5.4400
fγw = 1.7079
(1) fa / fs = −3.6994
(4) | fw / ff | = 0.4204
(5) | fγw | = 1.7079
(6) ff / fs = 0.6083
(7) (d1-2) /ft=0.1869

  FIG. 18 is a diagram illustrating various aberrations of the lens system according to Example 5 in the infinitely focused state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Respectively.

  FIGS. 19A and 19B are graphs showing various aberrations of the lens system according to Example 5 in a short-distance in-focus state (shooting magnification—0.01 times), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  FIG. 20 is a coma aberration diagram of the lens system according to Example 5 in a lens shift state (0.2 mm) in an infinitely focused state, where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  From each aberration diagram, it can be seen that the lens system according to Example 5 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Sixth embodiment)
FIG. 21 is a sectional view showing the structure of a lens system according to the sixth example.

  As shown in FIG. 21, the lens system according to Example 6 includes, in order from the object side along the optical axis, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. And the first lens group G1 and the second lens group so that the air gap between the first lens group G1 and the second lens group G2 is reduced upon zooming from the wide-angle end state W to the telephoto end state T. G2 moves.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface directed toward the object side, a biconcave lens L12, a positive meniscus lens L13 having a convex surface directed toward the object side, and an object side And a positive meniscus lens L14 having a convex surface. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens having an aspheric surface on the image plane I side.

  The second lens group G2, in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex lens L22, an aperture stop S, and a convex surface facing the object side. A positive meniscus lens L23, a positive meniscus lens L24 having a convex surface facing the object side, a cemented negative lens of a positive meniscus lens L25 having a concave surface facing the object side and a biconcave lens L26, and a biconvex lens L27. Yes. The positive meniscus lens L24 of the second lens group G2 is an aspheric lens having an aspheric surface on the image plane I side. The biconvex lens L27 located closest to the image plane I in the second lens group G2 is an aspherical lens in which an aspheric surface is formed on the image plane I side.

  The aperture stop S arranged in the second lens group G2 moves together with the second lens group G2 toward the object side during zooming from the wide-angle end state W to the telephoto end state T.

  The positive meniscus lens L24 is a focusing lens group Gf, and the focusing lens group Gf is moved to the object side, thereby focusing from an infinite object to a short-distance object.

  The cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a decentered lens group Gs, and camera shake correction (anti-vibration) is performed by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The positive meniscus lens L23 is the auxiliary lens group Ga.

  Table 6 below provides specifications of the lens system according to the sixth example.

(Table 6)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 21.5900 1.80 1.77377 47.17
2 * 8.3834 5.81
3 -330.2204 0.80 1.75500 52.32
4 20.4287 0.90
5 34.6426 1.58 1.69895 30.13
6 56.8065 0.20
7 17.3398 2.42 1.80518 25.42
8 40.5926 (variable)

9 38.9358 0.80 1.84666 23.78
10 20.3696 2.02 1.64000 60.08
11 -52.1553 3.41
12 (Aperture) ∞ 0.40
13 8.7558 2.14 1.60300 65.44
14 11.3294 2.22
15 25.7295 1.53 1.77377 47.17
16 * 836.1941 1.70
17 -63.5509 1.90 1.49700 81.54
18 -10.3135 0.80 1.83481 42.71
19 12.9668 0.50
20 13.3653 2.59 1.66910 55.42
21 * -20.7258 (Bf)
Image plane ∞

(Aspheric data)
Second side κ = 0.6895
A4 = 2.9268E-06
A6 = 5.0186E-08
A8 = 2.0720E-09
A10 = -2.1936E-11
16th surface κ = 11.0000
A4 = 1.1167E-05
A6 = 1.2804E-06
A8 = -9.7386E-08
A10 = 2.7299E-09
21st surface κ = 3.1942
A4 = 1.5565E-04
A6 = 1.5752E-06
A8 = 1.9610E-08
A10 = 9.0671E-11

(Various data)
Zoom ratio 2.825
W M T
f = 10.30 18.75 29.10
FNO = 3.64 4.57 5.86
2ω = 78.82 46.27 30.58
Y = 7.96 7.96 7.96
TL = 75.78 69.22 73.78
Bf = 18.4425 27.8042 39.2710

d8 23.8288 7.9040 1.0000

(Focus lens group movement data)
W M T
f = 10.3000 18.7500 29.1000
ΔFx = 0.0661 0.0871 0.1004

(Zoom lens group data)
Group Start surface Focal length 1 1-18.1250
2 9 20.0807

(Values for conditional expressions)
fw = 10.3000
ft = 29.1000
ff = 34.2797
fs = 42.2410
fa = 48.6750
d1-2 = 5.8071
fγw = 1.5555
(1) fa / fs = 1.1523
(4) | fw / ff | = 0.005
(5) | fγw | = 1.5555
(6) ff / fs = 0.8115
(7) (d1-2) /ft=0.1996

  22A and 22B show various aberration diagrams of the lens system according to Example 6 in the infinitely focused state, where FIG. 22A is a wide-angle end state, FIG. 22B is an intermediate focal length state, and FIG. 22C is a telephoto end state. Respectively.

  23A and 23B are graphs showing various aberrations of the lens system according to Example 6 in a short-distance in-focus state (shooting magnification—0.01 times), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  FIGS. 24A and 24B show coma aberration diagrams of the lens system according to Example 6 in a lens shift state (0.2 mm) in an infinite focus state, where FIG. 24A is a wide-angle end state, and FIG. 24B is an intermediate focal length. The state (c) shows the telephoto end state.

  From each aberration diagram, it can be seen that the lens system according to Example 6 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Seventh embodiment)
FIG. 25 is a sectional view showing the structure of a lens system according to the seventh example.

  As shown in FIG. 25, the lens system according to Example 7 includes, in order from the object side along the optical axis, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. The third lens group G3 having positive refracting power is configured so that the air gap between the first lens group G1 and the second lens group G2 is reduced upon zooming from the wide-angle end state W to the telephoto end state T. In addition, the first lens group G1, the second lens group G2, and the third lens group G3 move so that the air gap between the second lens group G2 and the third lens group G3 decreases.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. ing. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens having an aspheric surface on the image plane I side.

  The second lens group G2 includes, in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L21 having a convex surface directed toward the object side and a biconvex lens L22, and a positive meniscus lens L23 having a convex surface directed toward the object side. And an aperture stop S, and a cemented negative lens composed of a positive meniscus lens L24 having a concave surface facing the object side and a biconcave lens L25. The positive meniscus lens L24 of the second lens group G2 is an aspheric lens having an aspheric surface on the object side.

  The third lens group G3 includes, in order from the object side along the optical axis, a biconvex lens L31, and a negative meniscus lens L32 having a convex surface facing the object side and a cemented negative lens of the biconvex lens L33. The biconvex lens L31 of the third lens group G3 is an aspheric lens having an aspheric surface on the image plane I side.

  The aperture stop S arranged in the second lens group G2 moves together with the second lens group G2 toward the object side during zooming from the wide-angle end state W to the telephoto end state T.

  The positive meniscus lens L23 is a focusing lens group Gf, and the focusing lens group Gf is moved to the object side, thereby focusing from an infinite object to a short distance object.

  The cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a decentered lens group Gs, and camera shake correction (anti-vibration) is performed by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The cemented negative lens of the positive meniscus lens L24 and the biconcave lens L25 is the auxiliary lens group Ga.

  Table 7 below provides specifications of the lens system according to the seventh example.

(Table 7)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 25.0000 1.80 1.74330 49.32
2 * 8.5722 5.23
3 -31.9974 0.80 1.49700 81.54
4 25.7099 0.15
5 16.2678 2.16 1.84666 23.78
6 33.0579 (variable)

7 27.3560 0.80 1.79504 28.69
8 12.7778 2.62 1.60300 65.44
9 -27.7840 3.04
10 10.6214 2.34 1.60300 65.44
11 28.5797 1.86
12 (Aperture) ∞ 1.10
13 * -27.4165 1.37 1.82115 24.06
14 -17.0648 0.80 1.75500 52.32
15 21.3149 (variable)

16 18.9858 2.05 1.67790 54.89
17 * -30.4460 0.15
18 155.5536 0.80 1.85026 32.35
19 12.8042 2.38 1.60300 65.44
20 -74.1840 (Bf)
Image plane ∞

(Aspheric data)
Second surface κ = 0.8028
A4 = -2.1183E-06
A6 = -2.6605E-09
A8 = 1.1966E-09
A10 = -3.0855E-11
13th surface κ = -7.4148
A4 = 2.7745E-05
A6 = -2.0384E-06
A8 = -2.7176E-07
A10 = -9.6003E-09
17th surface κ = 0.2983
A4 = 1.5880E-04
A6 = 1.8851E-06
A8 = -5.0971E-08
A10 = 8.8426E-10

(Various data)
Zoom ratio 2.825
W M T
f = 10.30 18.75 29.10
FNO = 3.64 4.23 5.86
2ω = 78.78 46.56 30.67
Y = 7.96 7.96 7.96
TL = 66.55 62.74 68.78
Bf = 15.4801 25.2812 36.7848

d6 17.8651 5.8489 1.0000
d15 3.7597 2.1640 1.5500

(Focus lens group movement data)
W M T
f = 10.3000 18.7500 29.1000
ΔFx = 0.0719 0.1246 0.1964

(Zoom lens group data)
Group Start surface Focal length 1 1 -15.542
2 7 26.5552
3 16 19.4757

(Values for conditional expressions)
fw = 10.3000
ft = 29.1000
ff = 26.7219
fs = 28.4536
fa = −15.9679
d1-2 = 5.2284
fγw = 1.4308
(1) fa / fs = −0.5612
(4) | fw / ff | = 0.3855
(5) | fγw | = 1.4308
(6) ff / fs = 0.9391
(7) (d1-2) /ft=0.1797

  FIG. 26 is a diagram illustrating various aberrations of the lens system according to Example 7 in an infinitely focused state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Respectively.

  FIGS. 27A and 27B are graphs showing various aberrations of the lens system according to Example 7 in a short-distance in-focus state (shooting magnification—0.01 times), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  28A and 28B are coma aberration diagrams in the lens shift state (0.2 mm) in the infinite focus state in the lens system according to Example 7. FIG. 28A is a wide-angle end state, and FIG. 28B is an intermediate focal length. The state (c) shows the telephoto end state.

  From the respective aberration diagrams, it can be seen that the lens system according to Example 7 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Eighth embodiment)
FIG. 29 is a sectional view showing the structure of a lens system according to the eighth example.

  As shown in FIG. 29, the lens system according to Example 8 is a single focus lens, and has a first lens group G1 having negative refractive power and positive refractive power in order from the object side along the optical axis. The second lens group G2.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. ing. The negative meniscus lens L11 located closest to the object side of the first lens group G1 is an aspheric lens having an aspheric surface on the image plane I side.

  The second lens group G2 includes, in order from the object side along the optical axis, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex lens L22, an aperture stop S, a biconvex lens L23, and the object side. A cemented positive lens with a negative meniscus lens L24 having a concave surface facing the lens, a negative meniscus lens L25 with a convex surface facing the object side, and a cemented positive lens with a negative meniscus lens L26 having a convex surface facing the object side and a biconvex lens L27. It is composed of The negative meniscus lens L21 located closest to the object side in the second lens group G2 is an aspheric lens having an aspheric surface on the object side. The biconvex lens L27 located closest to the image plane I in the second lens group G2 is an aspherical lens in which an aspheric surface is formed on the image plane I side.

  The cemented positive lens of the biconvex lens L23 and the negative meniscus lens L24 is a focusing lens group Gf. By moving the focusing lens group Gf to the object side, focusing from an object at infinity to a near object is performed.

  The cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a decentered lens group Gs, and camera shake correction (anti-vibration) is performed by moving the decentered lens group Gs in a direction substantially perpendicular to the optical axis.

  The negative meniscus lens L25 and the cemented positive lens of the negative meniscus lens L26 and the biconvex lens L27 are the auxiliary lens group Ga having negative refractive power.

  Table 8 below provides specification values of the lens system according to the eighth example. It should be noted that ft in conditional expression (7) corresponding to the conditional expression is the same as the focal length f of the entire lens system.

(Table 8)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 18.6779 1.30 1.85135 40.10
2 * 7.8525 7.25
3 -94.6821 1.00 1.83481 42.72
4 34.1506 0.31
5 18.6651 2.51 1.86074 23.06
6 78.9142 23.50
7 * 18.1125 1.30 1.83441 37.28
8 12.2772 1.76 1.59319 67.87
9 -2494.0282 3.99
10 (Aperture) ∞ 1.00
11 23.3375 1.67 1.74400 44.78
12 -19.5626 1.00 1.67270 32.11
13 -219.6865 2.59
14 106.9379 1.53 1.80486 24.73
15 28.0039 1.36
16 352.0524 0.83 1.79952 42.24
17 10.0128 2.17 1.69350 53.20
18 * -38.1016 18.73
Image plane ∞

(Aspheric data)
Second side κ = 0.6460
A4 = 1.2719E-05
A6 = 5.3251E-07
A8 = -4.7392E-09
A10 = 4.5963E-11
7th surface κ = -1.0893
A4 = 3.0467E-05
A6 = 9.8555E-08
A8 = -1.0556E-08
A10 = 2.2926E-10
18th surface κ = 1.0000
A4 = 6.6102E-05
A6 = 5.9125E-08
A8 = 3.8159E-08
A10 = -1.1681E-09

(Various data)
f = 10.30
FNO = 3.31
2ω = 77.59
Y = 7.96
TL = 73.80

(Focus lens group movement data)
f = 10.3000
ΔFx = 0.0669

(Values for conditional expressions)
f = 10.3000
ff = 26.0978
fs = 36.6504
fa = −98.3425
d1-2 = 7.2500
fγ = 1.5400
(1) fa / fs = −2.6833
(2) | f / ff | = 0.3947
(3) | fγ | = 1.5400
(6) ff / fs = 0.7121
(7) (d1-2) /ft=0.7039

  FIG. 30 shows various aberration diagrams of the lens system according to Example 8 in the infinite focus state.

  FIG. 31 is a diagram illustrating various aberrations of the lens system according to Example 8 in a short-distance in-focus state (imaging magnification: -0.01 times).

  FIG. 32 is a coma aberration diagram of the lens system according to Example 8 in the lens shift state (0.2 mm) in the infinite focus state.

  From each aberration diagram, it can be seen that the lens system according to the eighth example has excellent image forming performance with various aberrations corrected well.

  As described above, according to the present embodiment, it is possible to provide a lens system having a wide field angle, a small size, and high imaging performance by making the inner focusing method and the decentered lens group compatible.

  Next, a camera equipped with the lens system according to this embodiment will be described. Although the case where the lens system according to the first example is mounted will be described, the same applies to other examples.

  FIG. 33 is a diagram illustrating a configuration of a camera including the lens system according to the first example.

  In FIG. 33, the camera 1 is a digital single-lens reflex camera provided with the lens system according to the first embodiment as the photographing lens 2. In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and is focused on the focusing screen 4 via the quick return mirror 3. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image through the eyepiece 6.

  When the release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 7. As a result, light from the subject is picked up by the image sensor 7 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

  By mounting the lens system according to the first embodiment as the photographing lens 2 on the camera 1, a camera having high performance can be realized.

  The outline of the manufacturing method of the lens system of the present application will be described below.

  FIG. 34 is a diagram showing a manufacturing method of the lens system of the present application.

  The lens system manufacturing method of the present application is a method of manufacturing a lens system that includes a plurality of lens groups, and the lens group on the image side of the lens group closest to the object side has a positive refractive power, and is shown in FIG. Includes S1 and S2.

  Step S1: A lens on the most object side includes a focusing lens group that performs focusing from an object at infinity to an object at a short distance, and an eccentric lens group that can move so as to have a component in a direction perpendicular to the optical axis. The lens group is located on the image side of the group.

  Step S2: The focusing lens group is disposed on the image side of the decentered lens group.

  According to the manufacturing method of the lens system of the present application, it is possible to manufacture a lens system that is compact and has high imaging performance by making the inner focusing method and the eccentric lens group compatible.

  The contents described below can be appropriately adopted as long as the optical performance is not impaired.

  In the embodiment, the two-group and three-group configurations are shown, but the present invention can also be applied to other group configurations such as the four groups. Further, a configuration in which a lens or a lens group is added to the most object side or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during zooming.

  A single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. The focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, it is preferable that at least a part of the second lens group is a focusing lens group.

  In addition, the lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or is rotated (swayed) in the in-plane direction including the optical axis to reduce image blur caused by camera shake. It may be a decentered lens group to be corrected. In particular, it is preferable that at least a part of the second lens group is an eccentric lens group.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface.

  When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance.

  When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  The aperture stop is preferably disposed in the second lens group, but the role may be substituted by a lens frame without providing a member as the aperture stop.

  Further, each lens surface may be provided with an antireflection film having a high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast.

  The lens system of the present embodiment has a zoom ratio of about 2-5.

  In the lens system of the present embodiment, it is preferable that the first lens group has one positive lens component and two negative lens components, or two positive lens components and two negative lens components. In the first lens group, it is preferable that lens components are arranged in the order of negative / negative / positive / negative / positive / positive in order from the object side with an air gap interposed therebetween.

  In the lens system of the present embodiment, it is preferable that the second lens group has at least one positive lens component and one negative lens component.

  In addition, the lens system (zoom lens or single focus lens) according to the present embodiment has the smallest distance (back focus) on the optical axis from the image side surface to the image surface of the lens component arranged closest to the image side. The thickness is preferably about 10 to 30 mm.

  In the lens system (zoom lens or single focus lens) according to the present embodiment, the image height is preferably 5 to 12.5 mm, and more preferably 5 to 9.5 mm.

  In addition, in order to explain the present invention in an easy-to-understand manner, the configuration requirements of the embodiment have been described, but the present invention is not limited to this.

G1 First lens group G2 Second lens group Gf Focusing lens group Gs Decentered lens group Ga Auxiliary lens group S Aperture stop L11 Negative meniscus lens I Image plane 1 Camera

Claims (16)

Consists of a plurality of lens groups, the lens group on the image side of the most object side lens group has positive refractive power,
The lens group located on the image side of the lens group closest to the object side moves so as to have a component in a direction perpendicular to the optical axis and a focusing lens group that performs focusing from an object at infinity to a near object. A decentered lens group capable of
The lens system, wherein the focusing lens group is disposed on the image side of the decentered lens group.   During zooming from the wide-angle end state to the telephoto end state, the distance between the lens unit closest to the object side and the lens unit located on the image side of the lens unit closest to the object side changes, and the lens group closest to the object side changes. The lens system according to claim 1, wherein the lens group on the image side moves toward the object side.   The lens system according to claim 1, wherein the lens group closest to the object has a negative refractive power.   4. The lens system according to claim 1, wherein the most object side lens group and the lens group on the image side of the most object side lens group are adjacent to each other. 5.   The lens system according to any one of claims 1 to 4, wherein an aperture stop is disposed between the focusing lens group and the decentered lens group.   6. The lens system according to claim 1, further comprising an auxiliary lens group on at least one of the object side and the image side of the decentered lens group. The lens system according to claim 6, wherein the following condition is satisfied.
-11.00 <fa / fs <11.00
However,
fa: focal length of the auxiliary lens group fs: focal length of the decentered lens group The lens system according to claim 1, wherein the following condition is satisfied.
0.05 <| f / ff | <0.65
However,
f: focal length of the entire lens system ff: focal length of the focusing lens group The lens system according to claim 1, wherein the following condition is satisfied.
0.05 <| fγ | <2.75
However,
fγ: image plane movement coefficient of the focusing lens group The lens system according to claim 2, wherein the following condition is satisfied.
0.05 <| fw / ff | <0.65
However,
fw: focal length of the entire lens system in the wide-angle end state ff: focal length of the focusing lens group The lens system according to claim 2, wherein the following condition is satisfied.
0.05 <| fγw | <2.75
However,
fγw: an image plane movement coefficient in the wide-angle end state of the focusing lens group The lens system according to claim 1, wherein the following condition is satisfied.
-4.00 <ff / fs <4.00
However,
ff: focal length of the focusing lens group fs: focal length of the decentering lens group The lens system according to claim 2, wherein the following condition is satisfied.
0.00 <(d1-2) / ft <1.50
However,
d1-2: Air space on the optical axis from the lens surface on the image side of the lens closest to the object side of the entire lens system to the lens surface on the object side of the lens immediately after that ft: Focal length of the entire lens system in the telephoto end state   The lens system according to claim 1, wherein the decentered lens group has an aspherical surface.   An optical apparatus comprising the lens system according to claim 1. The lens group which is composed of a plurality of lens groups and which is on the image side of the most object side lens group is a method for manufacturing a lens system having positive refractive power,
The focusing lens group for focusing from an object at infinity to an object at a short distance and an eccentric lens group capable of moving so as to have a component in a direction perpendicular to the optical axis Placed in the lens group on the image side,
A method of manufacturing a lens system, wherein the focusing lens group is disposed on the image side of the decentered lens group.

Images