JP2011107267A - Lens system, optical apparatus, method for manufacturing the lens system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens system which establishes both of an internal focusing system and a decentering lens group, is made compact and has excellent imaging performance, to provide an optical apparatus including the lens system, and a method for manufacturing the lens system. <P>SOLUTION: The lens system includes, in order from an object side, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. When zooming from a wide-angle end state W to a telephoto end state T, a distance between the first lens group G1 and the second lens group G2 varies, and the second lens group G2 moves. The second lens group G2 includes a focusing lens group Gf that carries out focusing from an infinity object to a close object, and a decentering lens group Gs that is movable so as to have a component in a direction perpendicular to an optical axis. <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, in order from the object side, a first lens group having negative refractive power and a second lens group having positive refractive power, from the wide-angle end state to the telephoto end state. , The distance between the first lens group and the second lens group changes, the second lens group moves, and the second lens group focuses from an object at infinity to a near object. And a decentering lens group capable of moving so as to have a component in a direction perpendicular to the optical axis.

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

  In addition, the present invention is a method for manufacturing a lens system having, in order from the object side, a first lens group having negative refractive power and a second lens group having positive refractive power, from the wide-angle end state to the telephoto end state. During zooming, the distance between the first lens group and the second lens group can be changed, the second lens group can be moved, and focusing can be performed from an object at infinity to a near object. A lens group and a decentered lens group that can move so as to have a component in a direction perpendicular to the optical axis are disposed in the second lens group, and the focusing lens group is located on the object side of the decentered lens group. A method of manufacturing a lens system is provided.

  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 (0.1 mm) of the infinite focus state of the lens system which concerns on 1st Example is shown, (a) shows a wide-angle end state, (b) shows a telephoto end state, respectively. 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 (0.1 mm) of the infinite focus state of the lens system which concerns on 2nd Example is shown, (a) shows a wide angle end state, (b) shows a telephoto end state, respectively. 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 (0.1 mm) of the infinite focus state of the lens system which concerns on 3rd Example is shown, (a) shows a wide-angle end state, (b) shows a telephoto end state, respectively. 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 (0.1 mm) of the infinite focus state of the lens system which concerns on 4th Example is shown, (a) shows a wide-angle end state, (b) shows a telephoto end state, respectively. 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 (0.1 mm) of the infinite focus state of the lens system which concerns on 5th Example is shown, (a) shows a wide-angle end state, (b) shows a telephoto end state, respectively. 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 (0.1 mm) of the infinite focus state of the lens system which concerns on 6th Example is shown, (a) shows a wide-angle end state, (b) shows a telephoto end state, respectively. 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 (0.1 mm) of the infinite focus state of the lens system which concerns on 7th Example is shown, (a) shows a wide angle end state, (b) shows a telephoto end state, respectively. It is sectional drawing which shows the structure of the lens system which concerns on 8th Example. The aberration diagrams of the lens system according to Example 8 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 8 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 infinite focus state of the lens system which concerns on 8th 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 9th Example. The aberration diagrams of the lens system according to Example 9 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 shows various aberration diagrams of the lens system according to Example 9 in a short distance in-focus state (imaging magnification: 0.01 times), (a) is a wide-angle end state, (b) is an intermediate focal length 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 9th 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 10th Example. The aberration diagrams of the lens system according to Example 10 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 10 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 10th 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 11th Example. The aberration diagrams of the lens system according to Example 11 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 11 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 infinite focus state of the lens system which concerns on 11th 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 12th Example. The aberration diagrams of the lens system according to Example 12 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. 12A illustrates various aberration diagrams of the lens system according to Example 12 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 infinite focus state of the lens system which concerns on 12th 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 13th Example. The aberration diagrams of the lens system according to Example 13 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 13 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 13th 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 14th Example. The aberration diagrams of the lens system according to Example 14 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 14 in a short distance in-focus state (capturing 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 14th 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 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, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and zooming from the wide-angle end state to the telephoto end state. At this time, the distance between the first lens group and the second lens group changes, the second lens group moves, and the second lens group includes a focusing lens group that performs focusing from an object at infinity to a near object. And a decentered lens group capable of moving so as to have a component in a direction perpendicular to the optical axis. The decentered lens group is an anti-vibration lens group that corrects image blur caused by camera shake, and indicates a shift lens group or a tilt lens group.

  By disposing the focusing lens group and the decentering lens group in the second lens group, performance degradation that occurs when the decentering lens group is decentered and performance degradation that occurs when the focusing lens group moves are changed Fluctuation can be reduced.

  In the lens system according to the present embodiment, it is desirable that the focusing lens group is arranged on the object side of the decentered lens group.

  By disposing the decentered lens group on the image side with respect to the focusing lens group, image formation deterioration that occurs when the decentered lens group is decentered is not affected by focusing and can be easily controlled.

  In addition, the lens system according to the present embodiment preferably has an auxiliary lens group on the image side of the decentered lens group.

By arranging the auxiliary lens group on the image side of the decentered lens group, it is effective for decentering coma during image stabilization and image plane tilting, and it is possible to alleviate the deterioration of the imaging performance.
It is desirable to have an auxiliary lens group in the second lens group.

  By arranging the auxiliary lens group in the second lens group, it is effective for image plane fluctuation during focusing, decentering coma during image stabilization, and image plane tilting, and degradation of imaging performance can be alleviated.

  In the lens system according to the present embodiment, it is desirable that the auxiliary lens unit moves integrally with the focusing lens unit and the decentering lens unit during zooming.

  This configuration is effective for decentering coma during image stabilization and image plane tilting, and can reduce degradation of imaging performance.

  In the lens system according to the present embodiment, it is desirable that the auxiliary lens group has negative refractive power.

  Since the auxiliary lens group has negative refracting power, it is effective for coma aberration generated by the decentered lens group alone at the time of decentering, and fluctuation in deterioration of imaging performance can be reduced.

  In the lens system according to the present embodiment, it is desirable that the auxiliary lens group has a positive refractive power.

  Since the auxiliary lens group has positive refracting power, it is effective for spherical aberration generated by the decentered lens group alone at the time of decentering, and fluctuation in deterioration of imaging performance can be reduced.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (1).
(1) −7.20 <fa / fs <6.35
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.

  Exceeding the upper limit value of conditional expression (1) is not preferable because the focal length of the decentered lens unit becomes small and correction of coma and decentration coma becomes difficult. Moreover, it becomes difficult to control the position of the decentered lens group, and sufficient optical accuracy cannot be obtained, which is not preferable.

  If the lower limit of conditional expression (1) is not reached, the focal length of the decentered lens group becomes large, and a larger amount of lens shift is required to obtain a desired image shift amount, resulting in an increase in the size of the shift lens group. This is not preferable. 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 5.51. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (1) to 4.68. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (1) to 3.84.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (1) to −7.02. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit value of conditional expression (1) to −6.35. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (1) to −5.50. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (1) to −4.65.

  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 curvature of field at the time of lens shift, the lens group capable of image shift must be lens-shifted with a lens group close to a diaphragm where off-axis light flux passes near the optical axis during zooming. Thus, it is possible to maintain good imaging performance. Further, by disposing the focusing lens group near the stop, it is possible to reduce fluctuations in the field curvature during focusing from infinity to the closest distance.

  The lens system according to the present embodiment desirably has a lens component between the focusing lens group and the decentering lens group.

  This configuration is preferable because it is possible to suppress fluctuations in field curvature during focusing from the telephoto state to the short-distance state.

  In the lens system according to this embodiment, the second lens group includes, in order from the object side, a focusing lens group, a lens component, an aperture stop, an eccentric lens group, and an auxiliary lens group. Is desirable.

  With this configuration, the lens component is effective in suppressing fluctuations in the field curvature during focusing from the telephoto state to the short-distance state.

  In the lens system according to the present embodiment, the second lens group includes, in order from the object side, a focusing lens group, an aperture stop, a lens component, an eccentric lens group, and an auxiliary lens group. Is desirable.

  With this configuration, it is effective to reduce deterioration due to an eccentric piece generated during vibration isolation.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (2).
(2) 0.15 <| fw / ff | <0.45
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 (2) is a conditional expression for defining an appropriate range for the ratio of the focal length of the entire lens system and the focal length of the focusing lens group in the wide-angle end state.

  If the upper limit value of conditional expression (2) is exceeded, the focal length of the focusing lens group becomes small and position control on the optical axis of the focusing lens group becomes difficult, and sufficient optical accuracy can be obtained. This is not preferable. Further, spherical aberration and coma aberration due to the focusing lens group alone are generated, which is not preferable.

  If the lower limit value of conditional expression (2) is not reached, the focal length of the focusing lens group becomes large, the amount of movement during focusing becomes large, the entire lens system becomes long and the diameter becomes large, and the zoom lens The entire system becomes large and it is not preferable to reduce the size. In addition, it is not preferable because correction of spherical aberration and coma aberration by the focusing lens unit alone is insufficient.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.43. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (2) to 0.41. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (2) to 0.38.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.17. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.19. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.21. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.23.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (3).
(3) 0.15 <| fγw | <0.60
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 (3) defines the image plane movement coefficient of the focusing lens group, and is a conditional expression for minimizing a change in imaging performance from infinity to the shortest shooting distance.

  If the upper limit of conditional expression (3) is exceeded, the focal length of the focusing lens group becomes large, the amount of movement during focusing becomes large, the entire lens system becomes long, and the diameter becomes large. The entire system becomes large and it is not preferable to reduce the size. In addition, it is not preferable because correction of spherical aberration and coma aberration by the focusing lens unit alone is insufficient.

  If the lower limit value of conditional expression (3) is not reached, the focal length of the focusing lens group becomes small and position control on the optical axis of the focusing lens group becomes difficult, and sufficient optical accuracy can be obtained. This is not preferable. Further, spherical aberration and coma aberration due to the focusing lens group alone are generated, 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 0.58. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (3) to 0.55. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (3) to 0.53.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.18. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (3) to 0.22. 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 addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (4).
(4) -3.70 <ff / fs <3.10
Here, ff is the focal length of the focusing lens group, and fs is the focal length of the eccentric lens group.

  Conditional expression (4) is a conditional expression for defining an appropriate range for the focal length ratio of the focusing lens group and the decentering lens group.

  If the upper limit of conditional expression (4) is exceeded, the focal length of the focusing lens group becomes large, the amount of movement during focusing becomes large, the entire lens system becomes long and the diameter becomes large, and the zoom lens The entire system becomes large and it is not preferable to reduce the size. In addition, it is not preferable because correction of spherical aberration and coma aberration by the focusing lens unit alone is insufficient. Alternatively, the focal length of the decentered lens group becomes small, and it becomes difficult to control the position in the direction perpendicular to the optical axis of the decentered lens group, making it difficult to correct coma and decentration coma, and sufficient optical accuracy. It cannot be obtained, which is not preferable.

  If the lower limit value of conditional expression (4) is not reached, the focal length of the focusing lens group becomes small and position control on the optical axis of the focusing lens group becomes difficult, and sufficient optical accuracy can be obtained. This is not preferable. Further, spherical aberration and coma aberration due to the focusing lens group alone are generated, which is not preferable. Alternatively, the focal length of the decentered lens group is increased, and a larger amount of lens shift is required to obtain a desired image shift amount, which increases the size of the shift lens group, which is not preferable. 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 2.68. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (4) to 2.25. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (4) to 1.83.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (4) to −3.27. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (4) to −2.84. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (4) to −2.41.

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

  With this configuration, it is possible to control the eccentric coma during image stabilization and correct the curvature of field well.

  In the lens system according to the present embodiment, it is desirable that the most object side lens of the first lens group has an aspherical surface.

  With this configuration, it is possible to satisfactorily correct curvature of field and curvature of field due to zoom variation.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (5).
(5) 0.00 <(d1-2) / ft <1.20
Here, d1-2 is the air space on the optical axis from the image side lens surface of the lens closest to the object side of the first lens group to the object side lens surface of the lens immediately after that, and ft is the lens in the telephoto end state. The focal length of the entire system.

  Conditional expression (5) 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 of the first lens group to the lens surface on the object side of the lens immediately thereafter.

  When the upper limit value of conditional expression (5) is exceeded, the air space on the optical axis from the image side lens surface of the lens closest to the object side in the first lens group to the lens surface on the object side of the lens immediately thereafter is remarkably large. Become wider. As a result, the first lens group having negative refracting power is thickened, the lens on the most image side is enlarged, the manufacturing cost is increased, and the entire lens system is enlarged, which is not preferable. Further, the correction of spherical aberration is insufficient, which is not preferable.

  If the lower limit value of conditional expression (5) is not reached, the focal length of the lens closest to the object side becomes large, and correction of distortion aberration, astigmatism due to zoom fluctuation, and field curvature 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 (5) to 1.11. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (5) to 1.03. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (5) to 0.94.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (5) 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 (5) 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 (5) to 0.13.

  In the lens system according to the present embodiment, it is desirable that the lens located closest to the image side of the entire lens system has an aspherical surface.

  With this configuration, it is possible to satisfactorily correct astigmatism and field curvature.

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

  With this configuration, it is possible to suppress fluctuations in field curvature during focusing from the telephoto state to the short-distance state.

  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 fluctuations in spherical aberration and coma generated by the decentered lens unit alone, and to minimize performance degradation during lens shift, which is also advantageous for correcting curvature of field. It becomes.

  In the lens system according to the present embodiment, it is desirable that the most object side lens of the auxiliary lens group has an aspherical surface.

  With this configuration, astigmatism, field curvature, and distortion can be favorably corrected.

  In the lens system according to the present embodiment, it is desirable that the focusing lens group has positive refractive power.

  With this configuration, spherical aberration can be corrected satisfactorily.

  In the lens system according to the present embodiment, it is desirable that the decentered lens group has positive refractive power.

  This configuration is effective in suppressing the variation of spherical aberration that occurs during decentration.

  The lens system according to the present embodiment can satisfactorily correct the spherical aberration, the sine condition, and the Petzval sum so that the image is good when the lens is shifted. The spherical aberration and the sine condition are corrected in order to suppress decentration coma generated at the center of the screen when the shift lens group is shifted in a direction substantially orthogonal 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 in a direction substantially orthogonal to the optical axis. In addition, when the lens is shifted, it is preferable to perform image shift by shifting the whole or a part of the decentered lens group in a direction substantially orthogonal to the optical axis to correct image blur on the image plane when camera shake occurs.

  In the lens system according to the present embodiment, it is desirable that the decentered lens group is composed of a cemented lens.

  With this configuration, it is possible to satisfactorily correct chromatic aberration and spherical aberration generated by the decentered lens group alone.

  In the lens system according to the present embodiment, it is desirable that the decentered lens group is composed of a single lens.

  This configuration is preferable because the decentered lens group can be reduced in size and reduced in weight.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (6).
(6) | βG2fw |> 2.00
However, βG2fw is the imaging magnification of the focusing lens group in the wide-angle end state.

  Conditional expression (6) is a conditional expression regarding the imaging magnification of the focusing lens group in the wide-angle end state.

  If the lower limit value of conditional expression (6) is not reached, the change due to zooming of the focusing lens group is large, which is not preferable.

In addition, it is desirable that the lens system according to the present embodiment satisfies the following conditional expression (7).
(7) | βG2ft |> 2.00
However, βG2ft is the imaging magnification of the focusing lens group in the telephoto end state.

  Conditional expression (7) is a conditional expression regarding the imaging magnification of the focusing lens group in the telephoto end state.

  If the lower limit value of conditional expression (7) is not reached, the change due to zooming of the focusing lens group is large, which is not preferable.

(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 negative meniscus lens L21 and the biconvex lens L22 is a focusing lens group Gf. By moving the focusing lens group Gf to the image plane I side, focusing from an object at infinity to a near object is performed. Do.

  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 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). D0 is the distance from the object to the lens surface closest to the object.

  (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 (variable)

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 = 77.58 49.65 30.52
Y = 7.962 7.962 7.962
TL = 73.80 67.53 72.19
Bf = 18.7255 26.4381 39.4394

d6 23.5020 9.5180 1.1743
d9 3.9922 3.9922 3.9922

(Focus lens group movement data)
W M T
f = 10.3000 17.3000 29.0999
ΔFx = 0.36655 0.18679 0.11743
Interval data at shooting magnification -0.01x
d0 1007.2359 1711.1536 2893.2744
f 10.16856 17.14450 28.85935
d6 23.86855 9.70478 1.29170
d9 3.62564 3.80541 3.87477
Bf 18.72545 26.43808 39.43937

(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 = 36.6504
fs = 26.0978
fa = −98.3425
d1-2 = 7.2500
fγw = −0.282
βG2fw = −2.668
βG2ft = 4.265
(1) fa / fs = −3.7768
(2) | fw / ff | = 0.281
(3) | fγw | = 0.282
(4) ff / fs = 1.404
(5) (d1-2) /ft=0.249
(6) | βG2fw | = 2.668
(7) | βG2ft | = 4.265

  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 (0.1 mm) in the infinitely focused state of the lens system according to the first example, where FIG. 4A is a wide-angle end state and FIG. 4B is a telephoto end state. Respectively.

  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”). D represents a d-line (λ = 587.6 nm), and g represents a g-line (λ = 435.8 nm). 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 cemented positive lens of the negative meniscus lens L21 and the positive meniscus lens L22 is a focusing lens group Gf. By moving the focusing lens group Gf to the image plane I side, focusing from an object at infinity to a near object is performed. I do.

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

  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 (variable)

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 = 78.16 49.68 30.56
Y = 7.962 7.962 7.962
TL = 74.56 70.81 77.93
Bf = 20.7334 29.3225 43.8013

d8 21.1546 8.8150 1.4524
d11 4.0108 4.0108 4.0108

(Focus lens group movement data)
W M T
f = 10.3000 17.3001 29.1002
ΔFx = 0.26202 0.14965 0.09679
Interval data at shooting magnification -0.01x
d0 1010.2853 1712.6264 2894.1760
f 10.20052 17.16716 28.88711
d8 21.41652 8.96456 1.54914
d11 3.74878 3.86115 3.91401
Bf 20.73340 29.32251 43.80132

(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 = 37.5001
fs = 46.2923
fa = 136.987
d1-2 = 5.2957
fγw = −0.394
βG2fw = −4.4851
βG2ft = 3.3066
(1) fa / fs = 2.959
(2) | fw / ff | = 0.275
(3) | fγw | = 0.394
(4) ff / fs = 0.810
(5) (d1-2) /ft=0.182
(6) | βG2fw | = 4.485
(7) | βG2ft | = 3.307

  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 (0.1 mm) in the infinitely focused state of the lens system according to Example 2, where FIG. 8A is a wide-angle end state and FIG. 8B is a telephoto end state. Respectively.

  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 positive lens of the negative meniscus lens L21 and the positive meniscus lens L22 is a focusing lens group Gf. By moving the focusing lens group Gf to the image plane I side, focusing from an object at infinity to a near object is performed. I do.

  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 cemented negative lens of the biconcave lens L26 and the biconvex lens L27 is the auxiliary lens group Ga.

  A positive meniscus lens L23, which is a lens component, is disposed between the focusing lens group Gf and the decentering lens group Gs.

  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 (variable)

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 = 7.962 7.962 7.962
TL = 74.59 69.93 76.27
Bf = 19.7396 28.1183 42.2423

d8 22.2705 9.2305 1.4500
d11 4.2370 4.2370 4.2370

(Focus lens group movement data)
W M T
f = 10.3000 17.3001 29.1002
ΔFx = 0.29387 0.16110 0.10384
Interval data at shooting magnification -0.01x
d0 1008.7799 1711.7323 2893.5651
f 10.19058 17.16189 28.88227
d8 22.56436 9.39160 1.55387
d11 3.94313 4.07590 4.13316
Bf 19.73960 28.11827 42.24230

(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 = 36.2513
fs = 40.0000
fa = −52.4471
d1-2 = 5.1881
fγw = −0.3513
βG2fw = 3.5011
βG2ft = 3.4637
(1) fa / fs = −1.311
(2) | fw / ff | = 0.284
(3) | fγw | = 0.351
(4) ff / fs = 0.906
(5) (d1-2) /ft=0.178
(6) | βG2fw | = 3.501
(7) | βG2ft | = 3.464

  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 (0.1 mm) in the infinitely focused state of the lens system according to Example 3. FIG. 12A is a wide-angle end state, and FIG. 12B is a telephoto end state. Respectively.

  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 positive meniscus lens L21 is a focusing lens group Gf, and 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 negative meniscus lens L24 and the biconvex lens L25 is a decentered lens group Gs, and camera shake correction (antivibration) is performed 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.

  A cemented positive lens of a biconvex lens L22 and a negative meniscus lens L23, which are lens components, is disposed between the focusing lens group Gf and the decentered lens group Gs.

  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 (variable)

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 = 7.962 7.962 7.962
TL = 70.23 68.58 69.98
Bf = 14.6644 19.2561 24.7483

d6 11.9986 5.7487 1.6581
d8 1.5974 1.5974 1.5974

(Focus lens group movement data)
W M T
f = 6.9000 9.5000 12.6100
ΔFx = 0.14189 0.09426 0.07147
Interval data at shooting magnification -0.01x
d0 675.3095 936.2195 1247.7556
f 6.85007 9.44449 12.54231
d6 12.14042 5.84296 1.72955
d8 1.45551 1.50314 1.52593
Bf 14.66442 19.25605 24.74834

(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 = 26.1912
fs = 35.2637
fa = 101.5495
d1-2 = 10.6000
fγw = −0.4872
βG2fw = −3.3912
βG2ft = 10.0072
(1) fa / fs = 2.880
(2) | fw / ff | = 0.263
(3) | fγw | = 0.487
(4) ff / fs = 0.743
(5) (d1-2) /ft=0.841
(6) | βG2fw | = 3.391
(7) | βG2ft | = 10.007

  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.

  FIGS. 16A and 16B are coma aberration diagrams in the lens shift state (0.1 mm) in the infinitely focused state of the lens system according to Example 4, where FIG. 16A is a wide-angle end state and FIG. 16B is a telephoto end state. Respectively.

  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 cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a focusing lens group Gf. By moving the focusing lens group Gf to the image plane I side, focusing from an object at infinity to a near object is performed. Do.

  The biconcave lens L24 is an eccentric lens group Gs, and performs camera shake correction (anti-vibration) by moving the eccentric lens group Gs in a direction substantially perpendicular to the optical axis.

  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 a positive refractive power.

  A positive meniscus lens L23, which is a lens component, is disposed between the focusing lens group Gf and the decentering lens group Gs.

  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 (variable)

10 ∞ 0.67
11 9.6847 1.93 1.60300 65.44
12 26.0017 1.00
13 (Aperture) ∞ 1.10
14 ∞ 0.20
15 -34215.1520 0.80 1.82080 42.71
16 * 16.7358 0.61
17 ∞ 1.15
18 20.3058 1.72 1.49700 81.54
19 -90.6802 0.80 1.83400 37.16
20 17.5527 0.44
21 12.3817 2.16 1.66910 55.42
22 * -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
16th surface κ = 0.1365
A4 = -3.4023E-05
A6 = 1.6026E-06
A8 = -2.1064E-07
A10 = 7.1553E-09
22nd 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 = 7.962 7.962 7.962
TL = 73.78 67.23 71.78
Bf = 20.0062 29.3544 40.8045

d6 23.7984 7.8948 1.0000
d9 6.9185 6.9185 6.9185

(Focus lens group movement data)
W M T
f = 10.3000 18.7500 29.1000
ΔFx = 4.45572 1.20699 0.57516
Interval data at shooting magnification -0.01x
d0 880.7722 1768.0822 2809.2484
f 8.91478 17.71087 28.02997
d6 37.47672 18.32442 10.79778
d9 2.46278 5.71151 6.34334
Bf 26.97504 36.32324 47.77340

(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 = 40.2798
fs = -20.3795
fa = 27.6231
d1-2 = 5.4400
fγw = −0.2994
βG2fw = −3.77065
βG2ft = 3.3760
(1) fa / fs = −1.355
(2) | fw / ff | = 0.256
(3) | fγw | = 0.299
(4) ff / fs = −1.976
(5) (d1-2) /ft=0.187
(6) | βG2fw | = 3.707
(7) | βG2ft | = 3.376

  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.

  20A and 20B are coma aberration diagrams in the lens shift state (0.1 mm) in the infinitely focused state of the lens system according to Example 5. FIG. 20A is a wide-angle end state, and FIG. 20B is a telephoto end state. Respectively.

  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 cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a focusing lens group Gf. By moving the focusing lens group Gf to the image plane I side, focusing from an object at infinity to a near object is performed. Do.

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

  A positive meniscus lens L23, which is a lens component, is disposed between the focusing lens group Gf and the decentering lens group Gs.

  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 (variable)

12 ∞ 0.40
13 (Aperture) ∞ 0.40
14 8.7558 2.14 1.60300 65.44
15 11.3294 2.22
16 25.7295 1.53 1.77377 47.17
17 * 836.1941 0.55
18 ∞ 1.15
19 -63.5509 1.90 1.49700 81.54
20 -10.3135 0.80 1.83481 42.71
21 12.9668 0.50
22 13.3652 2.59 1.66910 55.42
23 * -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
17th surface κ = 11.0000
A4 = 1.1167E-05
A6 = 1.2804E-06
A8 = -9.7386E-08
A10 = 2.7299E-09
23rd plane 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 = 7.962 7.962 7.962
TL = 75.78 69.22 73.78
Bf = 18.4425 27.8042 39.2710

d8 23.8288 7.9040 1.0000
d11 3.0141 3.0141 3.0141

(Focus lens group movement data)
W M T
f = 10.3000 18.7500 29.1000
ΔFx = 0.33741 0.17897 0.12482
Interval data at shooting magnification -0.01x
d0 887.6920 1768.8032 2809.1446
f 10.18868 18.59343 28.86569
d8 24.16620 8.08298 1.12481
d11 2.67669 2.83513 2.88928
Bf 18.44270 27.80445 39.27122

(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 = 42.2410
fs = 34.2797
fa = -65.0250
d1-2 = 5.8071
fγw = −0.3059
βG2fw = −4.3491
βG2ft = 3.2206
(1) fa / fs = −1.897
(2) | fw / ff | = 0.244
(3) | fγw | = 0.306
(4) ff / fs = 1.232
(5) (d1-2) /ft=0.200
(6) | βG2fw | = 4.349
(7) | βG2ft | = 3.221

  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.

  24A and 24B are coma aberration diagrams in the lens shift state (0.1 mm) in the infinitely focused state of the lens system according to Example 6. FIG. 24A is a wide-angle end state, and FIG. 24B is a telephoto end state. Respectively.

  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 cemented positive lens of the negative meniscus lens L21 and the biconvex lens L22 is a focusing lens group Gf. By moving the focusing lens group Gf to the image plane I side, focusing from an object at infinity to a near object is performed. Do.

  The cemented negative lens of the positive meniscus lens L24 and the biconcave 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 third lens group G3 is an auxiliary lens group Ga.

  A positive meniscus lens L23, which is a lens component, is disposed between the focusing lens group Gf and the decentering lens group Gs.

  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 (variable)

10 ∞ 0.68
11 10.6214 2.34 1.60300 65.44
12 28.5797 1.86
13 (Aperture) ∞ 1.10
14 * -27.4165 1.37 1.82115 24.06
15 -17.0648 0.80 1.75500 52.32
16 21.3149 0.55
17 ∞ (variable)

18 18.9858 2.05 1.67790 54.89
19 * -30.4460 0.15
20 155.5536 0.80 1.85026 32.35
21 12.8042 2.38 1.60300 65.44
22 -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
14th surface κ = -7.4148
A4 = 2.7745E-05
A6 = -2.0384E-06
A8 = -2.7176E-07
A10 = -9.6003E-09
19th 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 = 7.962 7.962 7.962
TL = 66.55 62.74 68.78
Bf = 15.4801 25.2812 36.7848

d6 17.8651 5.8489 1.0000
d9 2.3653 2.3653 2.3653
d17 3.2097 1.6140 1.0000

(Focus lens group movement data)
W M T
f = 10.3000 18.7500 29.1000
ΔFx = 0.27154 0.12586 0.0844
Interval data at shooting magnification -0.01x
d0 1006.0724 1855.1767 2891.6589
f 10.17755 18.59081 28.86119
d6 18.13661 5.97474 1.08438
d9 2.09376 2.23944 2.28090
d17 3.20972 1.61399 1.00000
Bf 15.48033 25.28137 36.78498

(Zoom lens group data)
Group Start surface Focal length 1 1 -15.542
2 7 26.5552
3 18 19.4757

(Values for conditional expressions)
fw = 10.3000
ft = 29.1000
ff = 28.4536
fs = −15.9679
fa = 19.4757
d1-2 = 5.2284
fγw = −0.38103
βG2fw = −2.5541
βG2ft = 4.9702
(1) fa / fs = −1.220
(2) | fw / ff | = 0.362
(3) | fγw | = 0.381
(4) ff / fs = −1.782
(5) (d1-2) /ft=0.180
(6) | βG2fw | = 2.554
(7) | βG2ft | = 4.970

  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 show coma aberration diagrams in the lens shift state (0.1 mm) in the infinitely focused state of the lens system according to Example 7. FIG. 28A is a wide-angle end state, and FIG. 28B is a telephoto end state. Respectively.

  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 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 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 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 8 below provides specification values of the lens system according to the eighth example.

(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 (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
(2) | fw / ff | = 0.3947
(3) | fγw | = 1.5400
(4) ff / fs = 0.7121
(5) (d1-2) /ft=0.2491

  FIG. 30 shows various aberration diagrams of the lens system according to Example 8 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. 31A and 31B are graphs showing various aberrations of the lens system according to Example 8 in a short distance in-focus state (imaging magnification: −0.01 times). FIG. The state (c) shows the telephoto end state.

  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, where (a) is the wide-angle end state, and (b) is the 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 8 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Ninth embodiment)
FIG. 33 is a sectional view showing the structure of a lens system according to the ninth example.

  As shown in FIG. 33, the lens system according to Example 9 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 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 9 below provides specifications of the lens system according to Example 9.

(Table 9)

(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
(2) | fw / ff | = 0.2611
(3) | fγw | = 1.5310
(4) ff / fs = 0.003
(5) (d1-2) /ft=0.1820

  FIG. 34 is a diagram illustrating various aberrations of the lens system according to Example 9 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. 35A and 35B are graphs showing various aberrations of the lens system according to Example 9 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. 36 is a coma aberration diagram of the lens system according to Example 9 in a lens shift state (0.2 mm) in an infinite focus 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 9 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Tenth embodiment)
FIG. 37 is a sectional view showing the structure of a lens system according to the tenth example.

  As shown in FIG. 37, the lens system according to the tenth 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 10 below lists specifications of the lens system according to Example 10.

(Table 10)

(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
(2) | fw / ff | = 0.1964
(3) | fγw | = 1.4369
(4) ff / fs = −1.3112
(5) (d1-2) /ft=0.1783

  FIG. 38 is a diagram illustrating various aberrations of the lens system according to Example 10 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.

  FIG. 39 is a diagram illustrating various aberrations of the lens system according to Example 10 in a short-distance focusing 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.

  40A and 40B are coma aberration diagrams in the lens shift state (0.2 mm) in the infinite focus state in the lens system according to Example 10. FIG. 40A is a wide-angle end state, and FIG. 40B 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 tenth example has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Eleventh embodiment)
FIG. 41 is a sectional view showing the structure of a lens system according to the eleventh example.

  As shown in FIG. 41, the lens system according to Example 11 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 11 below provides specifications of the lens system according to Example 11.

(Table 11)

(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
(2) | fw / ff | = 0.1957
(3) | fγw | = 0.6637
(4) ff / fs = 1.3464
(5) (d1-2) /ft=0.8406

  FIGS. 42A and 42B are graphs showing various aberrations of the lens system according to Example 11 in the infinite focus state, where FIG. 42A is a wide-angle end state, FIG. 42B is an intermediate focal length state, and FIG. 42C is a telephoto end state. Respectively.

  FIGS. 43A and 43B are graphs showing various aberrations of the lens system according to Example 11 in a short-distance in-focus state (shooting magnification−0.01 ×), where (a) is a wide-angle end state and (b) is an intermediate focal length. The state (c) shows the telephoto end state.

  44A and 44B show coma aberration diagrams in the lens shift state (0.2 mm) in the infinite focus state in the lens system according to Example 11, where FIG. 44A shows the wide-angle end state and FIG. 44B shows the 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 11 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Twelfth embodiment)
FIG. 45 is a sectional view showing the structure of a lens system according to the twelfth example.

  As shown in FIG. 45, the lens system according to Example 12 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 positive refractive power.

  Table 12 below provides specifications of the lens system according to Example 12.

(Table 12)

(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
(2) | fw / ff | = 0.4204
(3) | fγw | = 1.7079
(4) ff / fs = 0.06083
(5) (d1-2) /ft=0.1869

  46A and 46B show various aberration diagrams of the lens system according to Example 12 in the infinite focus state. FIG. 46A shows the wide-angle end state, FIG. 46B shows the intermediate focal length state, and FIG. 46C shows the telephoto end state. Respectively.

  47A and 47B are graphs showing various aberrations of the lens system according to Example 12 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. 48A and 48B are coma aberration diagrams in the lens shift state (0.2 mm) in the infinitely focused state of the lens system according to Example 12, where FIG. 48A is the wide-angle end state and FIG. 48B is the 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 12 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Thirteenth embodiment)
FIG. 49 is a sectional view showing the structure of a lens system according to the 13th example.

  As shown in FIG. 49, the lens system according to Example 13 includes, in order from the object side along the optical axis, a first lens group G1 having negative refracting power, and a second lens group G2 having positive refracting 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 13 below provides specifications of the lens system according to Example 13.

(Table 13)

(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
(2) | fw / ff | = 0.005
(3) | fγw | = 1.5555
(4) ff / fs = 0.8115
(5) (d1-2) /ft=0.1996

  FIG. 50 is a diagram illustrating various aberrations of the lens system according to Example 13 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. 51A and 51B are graphs showing various aberrations of the lens system according to Example 13 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. 52 is a coma aberration diagram of the lens system according to Example 13 in the lens shifted state (0.2 mm) in the infinite focus state, (a) is the wide-angle end state, and (b) is the 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 13 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(14th embodiment)
FIG. 53 is a sectional view showing the structure of a lens system according to the 14th example.

  As shown in FIG. 53, the lens system according to Example 14 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 a third lens group G3 having refractive power 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 14 below provides specifications of the lens system according to Example 14.

(Table 14)

(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
(2) | fw / ff | = 0.3855
(3) | fγw | = 1.4308
(4) ff / fs = 0.9391
(5) (d1-2) /ft=0.1797

  54A and 54B show various aberration diagrams of the lens system according to Example 14 in the infinitely focused state, where FIG. 54A is the wide-angle end state, FIG. 54B is the intermediate focal length state, and FIG. 54C is the telephoto end state. Respectively.

  FIGS. 55A and 55B are graphs showing various aberrations of the lens system according to Example 14 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.

  56A and 56B are coma aberration diagrams in the lens shift state (0.2 mm) in the infinite focus state in the lens system according to Example 14, where FIG. 56A is the wide-angle end state and FIG. 56B is the 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 14 has excellent imaging performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

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

  In FIG. 57, the camera 1 is a digital single-lens reflex camera provided with the lens system according to the first embodiment as the taking 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. 58 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 lens system manufacturing method including a first lens group having negative refractive power and a second lens group having positive refractive power in order from the object side, and is shown in FIG. Steps S1 to S3 are included.

  Step S1: At the time of zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group disposed in the cylindrical lens barrel can be changed, and the second lens group can be moved. To do.

  Step S2: 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 are used as the second lens group. Deploy.

  Step S3: The focusing lens group is disposed on the object 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 (30)

In order from the object side, the first lens group having a negative refractive power and the second lens group having a positive refractive power,
Upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the second lens group moves.
The second lens group includes a focusing lens group that performs focusing from an object at infinity to an object at a short distance, and a decentered lens group that can move so as to have a component in a direction perpendicular to the optical axis. A lens system characterized by that.   The lens system according to claim 1, wherein the focusing lens group is disposed on the object side of the decentered lens group.   The lens system according to claim 1, wherein an auxiliary lens group is provided on the image side of the decentered lens group.   The lens system according to claim 3, wherein the auxiliary lens group is included in the second lens group.   The lens system according to claim 3 or 4, wherein the auxiliary lens group moves integrally with the focusing lens group and the decentered lens group at the time of zooming.   The lens system according to claim 3, wherein the auxiliary lens group has a negative refractive power.   The lens system according to claim 3, wherein the auxiliary lens group has a positive refractive power. The lens system according to claim 3, wherein the following condition is satisfied.
−7.20 <fa / fs <6.35
However,
fa: focal length of the auxiliary lens group fs: focal length of the decentered lens group   The lens system according to any one of claims 1 to 8, wherein an aperture stop is disposed between the focusing lens group and the decentered lens group.   The lens system according to claim 1, further comprising a lens component between the focusing lens group and the decentered lens group.   The second lens group includes, in order from the object side, the focusing lens group, the lens component, the aperture stop, the decentered lens group, and the auxiliary lens group. Item 11. The lens system according to Item 10.   The second lens group includes, in order from the object side, the focusing lens group, the aperture stop, the lens component, the decentered lens group, and the auxiliary lens group. Item 11. The lens system according to Item 10. The lens system according to claim 1, wherein the following condition is satisfied.
0.15 <| fw / ff | <0.45
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 1, wherein the following condition is satisfied.
0.15 <| fγw | <0.60
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.
−3.70 <ff / fs <3.10
However,
ff: focal length of the focusing lens group fs: focal length of the decentering lens group   The lens system according to claim 10, wherein the lens component has an aspherical surface.   The lens system according to any one of claims 1 to 16, wherein the lens closest to the object side of the first lens group has an aspherical surface. The lens system according to claim 1, wherein the following condition is satisfied.
0.00 <(d1-2) / ft <1.20
However,
d1-2: the air space on the optical axis from the image side lens surface of the lens closest to the object side in the first lens group to the object side lens surface of the lens immediately thereafter ft: the entire lens system in the telephoto end state Focal length   The lens system according to any one of claims 1 to 18, wherein the lens located closest to the image side of the entire lens system has an aspherical surface.   The lens system according to claim 1, wherein the focusing lens group has an aspherical surface.   The lens system according to any one of claims 1 to 20, wherein the decentered lens group has an aspherical surface.   The lens system according to any one of claims 3 to 21, wherein a lens closest to the object side of the auxiliary lens group has an aspherical surface.   The lens system according to any one of claims 1 to 22, wherein the focusing lens group has a positive refractive power.   The lens system according to any one of claims 1 to 23, wherein the decentered lens group has a positive refractive power.   The lens system according to any one of claims 1 to 24, wherein the decentered lens group includes a cemented lens.   The lens system according to any one of claims 1 to 24, wherein the decentered lens group includes a single lens. 27. The lens system according to claim 1, wherein the following condition is satisfied.
| ΒG2fw |> 2.00
However,
βG2fw: imaging magnification of the focusing lens group in the wide-angle end state The lens system according to claim 1, wherein the following condition is satisfied.
| ΒG2ft |> 2.00
However,
βG2ft: imaging magnification of the focusing lens group in the telephoto end state   An optical apparatus comprising the lens system according to any one of claims 1 to 28. In order from the object side, a manufacturing method of a lens system having a first lens group having negative refractive power and a second lens group having positive refractive power,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group can be changed, and the second lens group can be moved,
A 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 are arranged in the second lens group. ,
A method of manufacturing a lens system, wherein the focusing lens group is disposed on the object side of the decentered lens group.

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