JP5181776B2 - Magnifying optical system, optical apparatus equipped with the magnifying optical system, and magnifying method of the magnifying optical system - Google Patents

Description

  The present invention relates to a variable magnification optical system, an optical apparatus including the variable magnification optical system, and a variable magnification method for the variable magnification optical system.

Scaling that can change the image position by moving a part of the lens so that it has a component perpendicular to the optical axis, which is suitable for conventional photographic cameras, electronic still cameras, video cameras, etc. An optical system has been proposed (see, for example, Patent Document 1).
JP 2006-085155 A

  However, the conventional variable magnification optical system has a problem that when a part of the lenses is moved so as to have a component in a direction perpendicular to the optical axis, good optical performance cannot be achieved.

  The present invention has been made in view of such problems, and zooming that can achieve good optical performance even if some lenses are moved so as to have a component perpendicular to the optical axis. An object is to provide an optical system.

In order to solve the above-described problem, the variable magnification optical system according to the first aspect of the present invention includes a front lens group and a rear lens group in order from the object side along the optical axis. In order from the front lens group and the rear lens group, the rear lens group, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, The third lens group having a positive refractive power and substantially consisting of five lens groups as a whole, and the front lens group and the first lens group when the lens position changes from the wide-angle end state to the telephoto end state. the distance between the lens groups vary, a first lens group distance between the second lens group increases in d12t from d12w, a second lens group spacing between the third lens group decreases the d23t from d23w, front Front lens group of lens group Distance between rear lens group changes, the second lens group includes in order from the object side, a first 2a partial lens unit having negative refractive power, and a portion 2b lens group having a negative refractive power Any one of the 2a partial lens group and the 2b partial lens group is configured to be movable so as to have a component in a direction perpendicular to the optical axis, and the 2a partial lens group is arranged in order from the object side. It consists of a cemented lens in which a concave lens and a positive meniscus lens having a convex surface facing the object side are cemented. In this variable magnification optical system, the combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group and the second lens group in the wide-angle end state are When the combined magnification with the third lens group is βw123 , the refractive index for the d-line of the positive meniscus lens of the 2a partial lens group is Np, and the refractive index for the d-line of the biconcave lens of the 2a partial lens group is Nn The following formula 0.002 <(d12t−d12w) /BL≦0.064
0.002 <(d23w-d23t) / BL <0.090
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
It is configured to satisfy the following conditions.
The variable magnification optical system according to the second aspect of the present invention includes a front lens group and a rear lens group in order from the object side along the optical axis, and the front lens group includes a front partial lens in order from the object side. The rear lens group includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group is composed of the third lens group, and substantially consists of five lens groups as a whole. The distance between the first lens group and the second lens group increases from d12w to d12t, the distance between the second lens group and the third lens group decreases from d23w to d23t, and the front portion of the front lens group Between the lens group and the rear lens group Interval changes, the second lens group includes in order from the object side, a first 2a partial lens unit having negative refractive power, and a portion 2b lens group having a negative refractive power, the 2a partial lens unit Alternatively, either one of the second-b partial lens groups is configured to be movable so as to have a component in a direction perpendicular to the optical axis, and the second-a partial lens group is convex from the object side to the biconcave lens and the object side. It consists of a cemented lens cemented with a positive meniscus lens facing. In this variable magnification optical system, the combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group and the second lens group in the wide-angle end state are When the combined magnification with the third lens group is βw123 , the refractive index for the d-line of the positive meniscus lens of the 2a partial lens group is Np, and the refractive index for the d-line of the biconcave lens of the 2a partial lens group is Nn The following formula 0.002 <(d12t−d12w) / BL <0.110
0.002 <(d23w−d23t) /BL≦0.064
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
It is configured to satisfy the following conditions.

Further, the variable magnification optical system according to the third aspect of the present invention includes a front lens group and a rear lens group in order from the object side along the optical axis, and the front lens group includes a front partial lens in order from the object side. The rear lens group includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group is composed of the third lens group, and substantially consists of five lens groups as a whole. The distance between the first lens group and the second lens group increases from d12w to d12t, the distance between the second lens group and the third lens group decreases from d23w to d23t, and the front portion of the front lens group Between the lens group and the rear lens group. Interval changes, the second lens group includes in order from the object side, a first 2a partial lens unit having negative refractive power, and a portion 2b lens group having a negative refractive power, the 2a partial lens unit Alternatively, either one of the second-b partial lens groups is configured to be movable so as to have a component in a direction perpendicular to the optical axis, and the second-a partial lens group is convex from the object side to the biconcave lens and the object side. It consists of a cemented lens cemented with a positive meniscus lens facing. In this variable magnification optical system, the combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group and the second lens group in the wide-angle end state are The composite magnification with the third lens group is βw123, the distance between the first lens group and the third lens group in the wide-angle end state is d13w, and the distance between the first lens group and the third lens group in the telephoto end state Is d13t , the refractive index for the d-line of the positive meniscus lens of the 2a partial lens group is Np, and the refractive index for the d-line of the biconcave lens of the 2a partial lens group is Nn, d12t−d12w) / BL <0.110
0.002 <(d23w-d23t) / BL <0.090
0.010 <(d12w / d13w) <0.400
0.050 ≦ (d23t / d13t) <0.400
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
It is configured to satisfy the following conditions.

The variable magnification optical system according to the fourth aspect of the present invention includes a front lens group and a rear lens group in order from the object side along the optical axis, and the front lens group includes a front partial lens in order from the object side. The rear lens group includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group is composed of the third lens group, and substantially consists of five lens groups as a whole. The distance between the first lens group and the second lens group increases from d12w to d12t, the distance between the second lens group and the third lens group decreases from d23w to d23t, and the front portion of the front lens group Between the lens group and the rear lens group. Interval changes, the second lens group includes in order from the object side, a first 2a partial lens unit having negative refractive power, and a portion 2b lens group having a negative refractive power, the 2a partial lens unit Alternatively, either one of the second-b partial lens groups is configured to be movable so as to have a component in a direction perpendicular to the optical axis, and the second-a partial lens group is convex from the object side to the biconcave lens and the object side. It consists of a cemented lens cemented with a positive meniscus lens facing. In this variable magnification optical system, the combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group and the second lens group in the wide-angle end state are When the combined magnification with the third lens group is βw123, and the amount of movement of the first lens group with respect to the image plane when the lens position changes from the wide-angle end state to the telephoto end state is Δx1, the following expression 0.002 < (D12t-d12w) / BL <0.110
0.002 <(d23w-d23t) / BL <0.090
0.440 <| Δx1 | / BL <1.00
However, BL = fw123 × (1-βw123)
It is configured to satisfy the following conditions.

Further, in the zoom optical system according to the first, second or fourth present invention, the distance between the first lens group and the third lens group in the wide-angle end state is d13w, and in the telephoto end state, When the distance between the first lens group and the third lens group is d13t, the following expression 0.010 <(d12w / d13w) <0.400
0.010 <(d23t / d13t) <0.400
It is preferable to satisfy the following conditions.

In the variable power optical systems according to the first to third aspects of the present invention, the amount of movement of the first lens unit relative to the image plane when the lens position changes from the wide-angle end state to the telephoto end state is Δx1, and The combined focal length of the first lens group, the second lens group, and the third lens group in the end state is fw123, and the combined magnification of the first lens group, the second lens group, and the third lens group in the wide-angle end state is βw123. Then, the following formula 0.300 <| Δx1 | / BL <1.00
However, BL = fw123 × (1-βw123)
It is preferable to satisfy the following conditions.

In such a variable magnification optical system, the focal length of the second lens group is f2, and the combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123. When the combined magnification of the first lens group, the second lens group, and the third lens group in the end state is βw123, the following expression 0.050 <(− f2) / BL <0.900
However, BL = fw123 × (1-βw123)
It is preferable to satisfy the following conditions.

In such a variable magnification optical system, the 2a partial lens group is movable so as to have a component in a direction perpendicular to the optical axis so as to change the image position. When the focal length of the group is fR2a and the focal length of the second b partial lens group is fR2b, the following expression 0.050 <fR2a / fR2b <3,000.
It is preferable to satisfy the following conditions.

Also, in such a variable magnification optical system, when the radius of curvature of the cemented surface of the cemented lens of the 2a partial lens group is Rs and the focal length of the second lens group is f2, the following formula 0.200 <Rs / (-F2) <3.0000
It is preferable to satisfy the following conditions.

In the variable magnification optical system according to the fourth aspect of the present invention , the refractive index with respect to the d-line of the positive meniscus lens of the second-a partial lens group is Np, and the refraction of the biconcave lens of the second-a partial lens group with respect to the d-line. When the rate is Nn, the following formula −0.150 <Np−Nn <0.150
It is preferable to satisfy the following conditions.

Also, in such a variable magnification optical system, when the Abbe number of the biconcave lens of the 2a partial lens group is νn and the Abbe number of the positive meniscus lens of the 2a partial lens group is νp, the following formula 5.000 < νn−νp <30.000
It is preferable to satisfy the following conditions.

  In such a variable magnification optical system, it is preferable that the second-b partial lens unit is composed of a negative meniscus lens having a concave surface facing the object side.

  In such a variable magnification optical system, it is preferable that the second lens group has at least one aspheric surface.

  In such a variable magnification optical system, it is preferable that the third lens group has at least one aspheric surface.

Further, in such a variable magnification optical system, the front lens group have a positive refractive power, the rear lens group have a negative refractive power, the lens position state changes from the wide-angle end state to the telephoto end state In doing so, it is preferable that the distance between the front lens group and the rear lens group is increased.

  In such a variable magnification optical system, it is preferable that the rear lens group has at least one aspherical surface.

  In addition, such a variable magnification optical system moves the first lens group and the third lens group in the object direction when the lens position changes from the wide-angle end state to the telephoto end state, and is relative to the image plane. It is preferable that the amount of movement is equal.

  Such a variable magnification optical system preferably has an aperture stop in the vicinity of the first lens group or in the first lens group.

  Further, in such a variable magnification optical system, it is preferable that the distance between the front lens group and the first lens group is reduced when the lens position state changes from the wide-angle end state to the telephoto end state.

  Also, such a variable magnification optical system moves the image of the second lens group so as to have a component in the direction perpendicular to the optical axis at the time of occurrence of camera shake. It is preferable that the correction is performed.

  An optical apparatus according to the present invention includes any of the above-described variable magnification optical systems.

The zooming method of the zooming optical system according to the present invention includes a front lens group and a rear lens group arranged in order from the object side along the optical axis, and the front lens group is arranged in front from the object side in order. A partial lens group and a rear partial lens group are arranged, and as a rear lens group, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refraction. When the lens position state changes from the wide-angle end state to the telephoto end state, the front lens group and the first lens group are arranged. the distance between the lens groups vary, a first lens group distance between the second lens group increases in d12t from d12w, a second lens group spacing between the third lens group decreases the d23t from d23w, front Front lens group and rear lens group Distance between lens groups is varied, the second lens group includes in order from the object side, a first 2a partial lens unit having negative refractive power, and a portion 2b lens group having negative refractive power, a Either the 2a partial lens group or the 2b partial lens group is configured to be movable so as to have a component in the direction perpendicular to the optical axis, and the second a partial lens group includes a biconcave lens in order from the object side. It consists of a cemented lens joined with a positive meniscus lens having a convex surface facing the object side, and the combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and in the wide-angle end state The combined magnification of the first lens group, the second lens group, and the third lens group is βw123 , the refractive index with respect to the d-line of the positive meniscus lens of the 2a partial lens group is Np, and the biconcave lens of the 2a partial lens group d When the refractive index with respect to the line is Nn , the following formula 0.002 <(d12t−d12w) /BL≦0.064
0.002 <(d23w-d23t) / BL <0.090
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
Satisfy the conditions.

  When the variable power optical system according to the present invention, the optical apparatus including the variable power optical system, and the variable power method of the variable power optical system are configured as described above, a part of the variable power optical system is configured with respect to the optical axis. Therefore, even if it is moved so as to have a vertical component, good optical performance can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the present specification, the wide-angle end state and the telephoto end state refer to an infinitely focused state unless otherwise specified. As shown in FIG. 1, the variable magnification optical system ZL includes a front lens group FG and a rear lens group RG in order from the object side along the optical axis. The rear lens group RG has a positive refractive power. Is composed of a first lens group RG1 having a negative refractive power, a second lens group RG2 having a negative refractive power, and a third lens group RG3 having a positive refractive power. When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the first lens group RG1 and the second lens group RG2 in the telephoto end state is d12t, and the first lens group RG1 in the wide-angle end state is set. The distance between the second lens group RG2 and the second lens group RG2 is d12w, the distance between the second lens group RG2 and the third lens group RG3 in the telephoto end state is d23t, and the second lens group RG2 and the third lens group RG3 in the wide-angle end state. Is the distance between the front lens group FG and the first lens group RG1, the distance between the first lens group RG1 and the second lens group RG2 increases from d12w to d12t, and the second lens The interval between the group RG2 and the third lens group RG3 is configured to decrease from d23w to d23t. With such a configuration, at the time of zooming from the wide-angle end state to the telephoto end state, the principal point position of the rear lens group RG can be moved from the image plane side to the object side, and the variable obtained by the rear lens group RG can be obtained. It is possible to make the entire system a highly variable optical system by increasing the double amount. Furthermore, it is possible to satisfactorily correct variations in field curvature and spherical aberration during zooming.

  In addition, the zoom optical system ZL moves at least a part of the second lens group RG2 so as to have a component in a direction perpendicular to the optical axis at the time of occurrence of camera shake. It is desirable to be configured to perform the correction. As described above, since the image plane fluctuation can be corrected at the time of occurrence of camera shake, the variable magnification optical system ZL can be used as an image stabilization optical system. Further, the second lens group RG2 is composed of a relatively small optical element, and it is possible to achieve both the size and weight reduction of the lens barrel and the image forming performance when image plane correction is performed when camera shake occurs. Note that at least a part of the second lens group RG2 may be moved so as to have at least a component in the direction perpendicular to the optical axis. Therefore, at least a part of the second lens group RG2 moves in a direction perpendicular to the optical axis, moves in an oblique direction with respect to the optical axis, or draws an arc with respect to the direction perpendicular to the optical axis. You may move.

  Further, in the zoom optical system ZL, the first lens group RG1 and the third lens group RG3 move in the object direction when the lens position changes from the wide-angle end state to the telephoto end state, and the image plane It is desirable that the amount of movement with respect to be equal. As described above, during zooming from the wide-angle end state to the telephoto end state, the first lens group RG1 and the third lens group RG3 are moved in the object direction, thereby reducing the overall length at the wide-angle end and various aberrations. Good correction can be achieved at the same time. Further, by making the movement amounts of the first lens group RG1 and the third lens group RG3 equal, the first lens group RG1 and the third lens group RG3 can be integrated. With this structure, the change in mutual decentration between the first lens group RG1 and the third lens group RG3 can be suppressed small during zooming from the wide-angle end state to the telephoto end state, and optical performance due to manufacturing errors can be suppressed. Degradation can be mitigated.

  Further, such a variable magnification optical system ZL has a combined focal length of the first lens group RG1, the second lens group RG2, and the third lens group RG3 in the wide-angle end state as fw123, and the first lens group in the wide-angle end state. When the combining magnification of RG1, the second lens group RG2, and the third lens group RG3 is βw123, it is desirable that the following conditional expressions (1) and (2) are satisfied.

0.002 <(d12t-d12w) / BL <0.110 (1)
0.002 <(d23w−d23t) / BL <0.090 (2)
However, BL = fw123 × (1-βw123)

  Conditional expression (1) defines the amount of change in the distance between the first lens group RG1 and the second lens group RG2 when the variable magnification optical system ZL moves from the wide-angle end state to the telephoto end state. Conditional expression (2) defines the amount of change in the distance between the second lens group RG2 and the third lens group RG3 when the variable magnification optical system ZL moves from the wide-angle end state to the telephoto end state. is there. By satisfying the conditional expressions (1) and (2), the zooming optical system ZL can satisfactorily change the aberration when the image plane is corrected when the camera shake occurs while ensuring a large zooming ratio. It can be corrected.

  If the upper limit value of conditional expression (1) is exceeded, the distance between the first lens group RG1 and the second lens group RG2 at the telephoto end becomes large, and it becomes difficult to correct spherical aberration and coma at the telephoto end. Further, when image plane correction is performed when camera shake occurs, the decentration coma aberration becomes excessive at the telephoto end, which is not preferable. In addition, the effect of this invention can be made more reliable by making the upper limit of conditional expression (1) into 0.100, 0.090, 0.050. On the other hand, if the lower limit value of conditional expression (1) is not reached, the variation in spherical aberration becomes large and the correction becomes difficult at the time of zooming from the wide-angle end state to the telephoto end state. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (1) into 0.010, 0.020, 0.040.

  When the upper limit value of conditional expression (2) is exceeded, the distance between the second lens group RG2 and the third lens group RG3 at the wide angle end becomes large, and the ray height of the off-axis peripheral rays at the wide angle end at the third lens group RG3 becomes large. growing. This makes it difficult to correct curvature of field and coma at the wide-angle end, which is not preferable. Further, when image plane correction is performed when camera shake occurs, off-axis peripheral rays at the wide-angle end greatly vary in the third lens group RG3, making it difficult to correct the eccentric image plane taole. In addition, the effect of this invention can be made more reliable by making upper limit of conditional expression (2) into 0.080, 0.065, 0.050. On the other hand, if the lower limit value of conditional expression (2) is not reached, the variation in field curvature becomes large and the correction becomes difficult at the time of zooming from the wide-angle end state to the telephoto end state. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (2) into 0.010, 0.020, 0.040.

  Further, in the zoom optical system ZL, the distance from the most image side surface of the first lens unit FG1 in the wide-angle end state to the most object side surface of the third lens unit FG3 is d13w, and in the telephoto end state. When the distance from the most image side surface of the first lens group FG1 to the most object side surface of the third lens group FG3 is d13t, it is preferable to satisfy the following conditional expressions (3) and (4). .

0.010 <(d12w / d13w) <0.400 (3)
0.010 <(d23t / d13t) <0.400 (4)

  By satisfying conditional expression (3), the present variable magnification optical system ZL can satisfactorily correct field curvature and distortion at the wide-angle end while realizing miniaturization of the variable magnification optical system ZL. . Exceeding the upper limit of conditional expression (3) is not preferable because negative field curvature at the wide-angle end becomes excessive and correction becomes difficult. In addition, the effect of this invention can be made more reliable by making the upper limit of conditional expression (3) into 0.300, 0.200, 0.160. On the other hand, if the lower limit of conditional expression (3) is not reached, the positive curvature of field at the wide-angle end and the positive distortion become excessive, which is not preferable. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (3) into 0.030, 0.050, 0.110.

  In addition, the present variable magnification optical system ZL can satisfactorily correct spherical aberration and curvature of field at the telephoto end by satisfying conditional expression (4). Exceeding the upper limit of conditional expression (4) is not preferable because positive spherical aberration and curvature of field at the telephoto end become excessive and correction becomes difficult. In addition, the effect of this invention can be made more reliable by making the upper limit of conditional expression (4) into 0.300, 0.250, 0.210. On the other hand, if the lower limit value of conditional expression (4) is not reached, negative spherical aberration and field curvature at the telephoto end become excessive and correction becomes difficult, which is not preferable. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (4) into 0.030, 0.040, 0.050.

  Further, in this variable magnification optical system ZL, the amount of movement of the first lens group RG1 relative to the image plane when the lens position changes from the wide-angle end state to the telephoto end state is Δx1, and the first lens group RG1 in the wide-angle end state. The combined focal length of the first lens group RG2, the second lens group RG3, and the third lens group RG3 is fw123, and the combined magnification of the first lens group RG1, the second lens group RG2, and the third lens group RG3 in the wide-angle end state is βw123. When, it is desirable to satisfy the following conditional expression (5).

0.300 <| Δx1 | / BL <1.00 (5)
However, BL = fw123 × (1-βw123)

  Conditional expression (5) defines the amount of movement of the first lens group RG1 relative to the image plane when the zooming optical system ZL zooms from the wide-angle end state to the telephoto end state. The zooming optical system ZL satisfies the conditional expression (5), so that the zooming ratio exceeds 5 times while maintaining good imaging performance when the image plane is corrected when camera shake occurs. It is possible to realize a highly variable magnification optical system.

  If the upper limit value of conditional expression (5) is exceeded, the lateral magnification (absolute value) of the first lens group RG1 and the third lens group RG3 at the telephoto end of the variable magnification optical system ZL increases, and spherical aberration and It becomes difficult to correct coma. Further, when image plane correction is performed when camera shake occurs, the decentration coma aberration becomes excessive at the telephoto end, making correction difficult, which is not preferable. There is also a problem that the amount of extension of the first lens group RG1 becomes large and the mechanical configuration becomes difficult. In order to compensate for this, it is necessary to increase the optical total length at the wide-angle end, but this is not preferable because the total length of the lens barrel increases. In addition, the effect of this invention can be made more reliable by making the upper limit of conditional expression (5) into 0.850, 0.750, 0.660. On the other hand, if the lower limit of conditional expression (5) is not reached, the amount of zooming earned by the rear lens group RG will be small, making it difficult to obtain a predetermined zooming ratio. In order to compensate for this, if the refractive powers of the first lens group RG1, the second lens group RG2, and the third lens group RG3 are increased, it becomes difficult to correct spherical aberration and coma at the telephoto end. Furthermore, it is not preferable because there arises a problem that the imaging performance is deteriorated due to a manufacturing error such as decentration between the lens groups, that is, the decentration coma aberration and the decentered image plane taole increase. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (5) into 0.440, 0.500, 0.600.

  Further, the variable magnification optical system ZL sets the focal length of the second lens group RG2 to f2, and the combined focal length of the first lens group RG1, the second lens group RG2, and the third lens group RG3 in the wide-angle end state to fw123. When the combined magnification of the first lens group RG1, the second lens group RG2, and the third lens group RG3 in the wide-angle end state is βw123, it is desirable that the following conditional expression (6) is satisfied.

0.050 <(− f2) / BL <0.900 (6)
However, BL = fw123 × (1-βw123)

  Conditional expression (6) defines the focal length of the second lens group RG2. By satisfying this conditional expression (6), the present variable magnification optical system ZL alleviates optical performance degradation due to manufacturing errors while maintaining good imaging performance when image plane correction is performed when camera shake occurs. can do. When the upper limit value of conditional expression (6) is exceeded, the refractive power of the second lens group RG2 becomes small, and the image stabilization correction coefficient (image position movement amount perpendicular to the optical axis ÷ vibration group movement perpendicular to the optical axis). Amount) becomes smaller. Accordingly, it is not preferable to increase the movement amount of the image stabilizing group because the decentration coma aberration and the decentered image plane taole at the telephoto end are significantly deteriorated. In addition, there is a problem that the lens barrel becomes large. In addition, the effect of this invention can be made more reliable by making the upper limit of conditional expression (6) into 0.520, 0.460, 0.380. On the other hand, if the lower limit of conditional expression (6) is not reached, the refractive power of the second lens group RG2 becomes large, and it becomes difficult to correct field curvature and coma at the wide-angle end. Further, it is not preferable because deterioration of imaging performance due to manufacturing errors such as decentration between lens groups, that is, deterioration of the decentered image plane is significant. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (6) into 0.110, 0.200, 0.280.

  In this variable magnification optical system ZL, the second lens group RG2 includes, in order from the object side, a second a partial lens group RG2a having a negative refractive power and a second b partial lens group RG2b having a negative refractive power. It is desirable that either the second-a partial lens group RG2a or the second-b partial lens group RG2b is movable so as to have a component perpendicular to the optical axis so as to change the image position. .

  With such a configuration, various aberrations of the positive refracting power component generated in the first lens group RG1 and the third lens group RG3 when the image plane correction at the time of the occurrence of camera shake is performed are the second lens group. It can be canceled by various aberrations of the negative refractive power component generated by the non-vibrated lens group in RG2, and can exhibit high aberration correction ability as a whole. Further, by dividing the second lens group RG2 into two, it becomes easy to change the refractive power of the image stabilization group, and the image stabilization correction coefficient (image position movement amount perpendicular to the optical axis / vertical to the optical axis). The direction of vibration isolation group movement in the direction) can be set to a desired value. As a result, for example, the amount of movement of the anti-vibration group in the direction perpendicular to the optical axis, which is a problem at the telephoto end of the high-magnification optical system, can be reduced, and the lens barrel diameter can be reduced.

  Further, in the variable magnification optical system ZL, it is preferable that the 2a partial lens group RG2a is configured to be movable so as to have a component in a direction perpendicular to the optical axis. At this time, when the focal length of the second-a partial lens group RG2a is fR2a and the focal length of the second-b partial lens group RG2b is fR2b, it is desirable to satisfy the following conditional expression (7).

0.050 <fR2a / fR2b <3,000 (7)

  Conditional expression (7) defines the focal length of the 2a partial lens group RG2a with respect to the focal length of the 2b partial lens group RG2b. By satisfying this conditional expression (7), the present variable magnification optical system ZL corrects decentration aberrations in a well-balanced manner at the time of image plane correction at the time of occurrence of camera shake in the entire region from the wide-angle end to the telephoto end. And good imaging performance can be obtained. When the upper limit value of conditional expression (7) is exceeded, the refractive power of the second b partial lens unit RG2b increases, and it becomes difficult to correct the decentered image plane at the wide-angle end when the image plane is corrected when camera shake occurs. Therefore, it is not preferable. In addition, the effect of this invention can be made more reliable by making the upper limit of conditional expression (7) into 1.500, 1.200, 1.050. On the other hand, if the lower limit of conditional expression (7) is not reached, the refractive power of the 2a partial lens group RG2a increases, and it is difficult to correct decentration coma at the telephoto end when image plane correction is performed when camera shake occurs. This is not preferable. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (7) into 0.300, 0.500, 0.850.

  In this variable magnification optical system ZL, it is desirable that the 2a partial lens group RG2a is composed of a cemented lens in which a biconcave lens and a positive meniscus lens having a convex surface facing the object side are cemented in order from the object side. With this configuration, the principal point position of the second lens group RG2 can be arranged on the image side, and the principal point interval between the second lens group RG2 and the third lens group RG3 can be reduced. This makes it possible to reduce the decentered image plane tilt at the wide-angle end of the variable magnification optical system ZL when performing image plane correction when camera shake occurs. In addition, there is an effect of reducing the diameter of the third lens group RG3.

  In the zoom optical system ZL, it is preferable that the second-b partial lens unit is composed of a negative meniscus lens having a concave surface facing the object side. By adopting such a configuration, it is possible to effectively compensate for a negative aberration component that is insufficient when image plane correction at the time of occurrence of camera shake is performed, and to suppress aberration fluctuation due to decentering to a small amount.

  When the 2a partial lens group RG2a is a cemented lens in this way, the radius of curvature of the cemented surface of the cemented lens of the 2a partial lens group RG2a is Rs, and the focal length of the second lens group RG2 is f2. In this case, it is desirable that the following conditional expression (8) is satisfied.

0.200 <Rs / (− f2) <3,000 (8)

  Conditional expression (8) defines the curvature of the cemented surface of the cemented lens of the 2a partial lens group RG2a with respect to the focal length of the second lens group RG2. Exceeding either the upper limit or the lower limit of conditional expression (8) is not preferable because it is difficult to correct spherical aberration, and decentration aberration is increased when image surface correction is performed when camera shake occurs. If the upper limit value of conditional expression (8) is exceeded, the curvature of the cemented surface becomes small and the positive spherical aberration becomes excessive, making correction difficult. In addition, the effect of this invention can be made more reliable by making the upper limit of conditional expression (8) 1.500, 1.000. On the other hand, if the lower limit of conditional expression (8) is not reached, the curvature of the cemented surface becomes large and the negative spherical aberration becomes excessive, making correction difficult. In addition, the effect of this invention can be made more reliable by making the minimum of conditional expression (8) into 0.400 and 0.800.

  In this case, when the refractive index with respect to the d line of the positive meniscus lens of the 2a partial lens group RG2a is Np and the refractive index with respect to the d line of the biconcave lens of the 2a partial lens group RG2a is Nn, the following conditions are satisfied. It is desirable to satisfy Expression (9).

-0.150 <Np-Nn <0.150 (9)

  Conditional expression (9) defines the relationship between the refractive index for the d-line of the biconcave lens of the 2a partial lens group RG2a and the refractive index for the d-line of the positive meniscus lens. Exceeding either the upper limit or the lower limit of conditional expression (9) is not preferable because the decentered image plane tilt at the time of image plane correction when camera shake occurs becomes large and correction becomes difficult. In order to secure the effect of the present invention, the upper limit of conditional expression (9) is preferably set to 0.100, 0.045, 0.020, and the lower limit of conditional expression (9) is set to −0. 100, −0.030 is preferable.

  Further, when the Abbe number of the biconcave lens of the 2a partial lens group RG2a is νn and the Abbe number of the positive meniscus lens of the 2a partial lens group RG2a is νp, the following conditional expression (10) is satisfied. desirable.

5.000 <νn−νp <30.000 (10)

  Conditional expression (10) defines the relationship between the Abbe number of the biconcave lens of the 2a partial lens group RG2a and the Abbe number of the positive meniscus lens. Exceeding either the upper limit or the lower limit of conditional expression (10) is not preferable because chromatic aberration generated in the second lens unit RG2 becomes excessive and correction becomes difficult. In order to secure the effect of the present invention, it is preferable that the upper limit of conditional expression (10) is 25.000, 19.000, and the lower limit of conditional expression (10) is 8.000, 11. 500 is preferable.

  By satisfying the conditional expressions (8) to (10) as described above, various aberrations and decentration aberrations at the time of occurrence of camera shake can be suppressed, and good imaging performance can be obtained.

  In the variable magnification optical system ZL, it is desirable that the second lens group RG2 has at least one aspheric surface. Thereby, the spherical aberration at the telephoto end and the decentration coma aberration at the telephoto end when the image plane correction at the time of the occurrence of camera shake can be favorably corrected.

  In the zoom optical system ZL, it is desirable that the third lens group RG3 has at least one aspheric surface. As a result, it is possible to satisfactorily correct the decentered image plane taole at the wide angle end when the image plane correction at the time of occurrence of camera shake is performed while satisfactorily correcting the image plane aberration and distortion at the wide angle end.

  In this variable magnification optical system ZL, the front lens group FG includes, in order from the object side, a front partial lens group FG1 having a positive refractive power and a rear partial lens group FG2 having a negative refractive power, When the lens position state changes from the wide-angle end state to the telephoto end state, it is desirable that the distance between the front partial lens group FG1 and the rear partial lens group FG2 increases. By adopting such a configuration, a large zoom ratio can be obtained, and high zoom ratio of the entire system can be achieved. Further, the zoom ratio of the first lens group RG1, the second lens group RG2, and the third lens group RG3 of the rear lens group RG can be reduced, and image formation is performed when image plane correction is performed when camera shake occurs. It is possible to improve performance.

  In the variable magnification optical system ZL, it is desirable that the rear lens group FG2 has at least one aspheric surface. Thereby, curvature of field and distortion at the wide-angle end can be corrected well, and a wide angle of view at the wide-angle end can be achieved.

  The variable magnification optical system ZL preferably has an aperture stop S on the object side of the second lens group RG2, that is, in the vicinity of the first lens group RG1 or in the first lens group RG1. By adopting such a structure, it is possible to achieve both a reduction in the front lens diameter and good correction of various aberrations.

  FIGS. 21 and 22 show a configuration of an electronic still camera 1 (hereinafter simply referred to as a camera) as an optical apparatus including the above-described variable magnification optical system ZL. In the camera 1, when a power button (not shown) is pressed, a shutter (not shown) of the photographing lens (variable magnification optical system ZL) is opened, and light from a subject (not shown) is condensed by the variable magnification optical system ZL. The image is formed on an image sensor C (for example, a CCD or a CMOS) disposed on the surface I. The subject image formed on the image sensor C is displayed on the liquid crystal monitor 2 disposed behind the camera 1. The photographer determines the composition of the subject image while looking at the liquid crystal monitor 2, and then presses the release button 3 to photograph the subject image with the image sensor C and records and saves it in a memory (not shown).

  The camera 1 includes an auxiliary light emitting unit 4 that emits auxiliary light when the subject is dark, and a wide (W) when zooming the zoom optical system ZL from the wide-angle end state (W) to the telephoto end state (T). A tele (T) button 5 and function buttons 6 used for setting various conditions of the camera 1 are arranged. 22 illustrates a compact type camera in which the camera 1 and the variable magnification optical system ZL are integrally formed. However, as an optical device, the lens barrel having the variable magnification optical system ZL and the camera body main body are attached and detached. A possible single-lens reflex camera may be used.

  In the above description and the embodiments described below, the overall configuration shows a two-group configuration (front lens group FG and rear lens group RG), and the rear lens group shows a variable power optical system ZL with a three-group configuration. The above-described configuration conditions and the like can be applied to the front lens group FG as one group configuration, or to other group configurations such as the fourth group and the fifth group as a whole. For example, in the present embodiment, the lens system of the rear lens group RG is composed of three movable groups, but another lens group is added between each lens group, or on the image side or object side of the lens system. It is also possible to add another lens group adjacent to each other.

  Alternatively, 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. In this case, the focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (such as an ultrasonic motor). In particular, in the case of the variable magnification optical system ZL having a total of five groups, it is preferable that at least a part of the front lens group FG is a focusing lens group. Further, when the front lens group FG is composed of one lens group, it is preferable to perform focusing with the first lens group RG1 of the front lens group FG or the rear lens group RG and a part of the first lens group RG1.

  Further, in the present embodiment, in order to prevent a shooting failure due to an image blur caused by a camera shake or the like that is likely to occur in a high-magnification optical system, a blur detection system that detects a blur of the optical system and a driving unit are used as a lens system. In combination, the entire or part of one of the lens groups constituting the lens system is decentered as an anti-vibration lens group, so that the image blur (image caused by the blur of the lens system detected by the blur detection system) It is possible to correct image blur by shifting the image by vibrating the anti-vibration lens group so that it has a component in the direction perpendicular to the optical axis to correct the fluctuations in the surface position). It is. In particular, it is preferable that at least a part of the second lens group RG2 constituting the rear lens group RG is an anti-vibration lens group. Further, the first lens group RG1 of the rear lens group RG may be used as an anti-vibration lens group. Thus, the variable magnification optical system ZL according to the present embodiment can function as a so-called vibration-proof optical system.

  In the above description, at least one aspheric lens is provided in either the second lens group RG2 or the third lens group RG3 of the rear lens group RG, or the rear lens group FG2 of the front lens group FG. Although the case of arrangement is shown, the lens surfaces of other lens groups may be aspherical. At this time, any one of an aspheric surface by grinding, a glass mold aspheric surface in which glass is formed into an aspheric shape by a mold, and a composite aspheric surface in which resin is formed in an aspheric shape on the surface of the glass may be used.

  The aperture stop S is preferably disposed on the object side of the second lens group RG2 as described above. However, the role of the aperture stop may be substituted by a lens frame without providing a member as an aperture stop.

  Furthermore, an antireflection film having a high transmittance in a wide wavelength region is applied to each lens surface, thereby reducing flare and ghost and achieving high optical performance with high contrast.

  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 it goes without saying that the present invention is not limited to this.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing the configuration of the variable magnification optical system ZL according to the present embodiment. The refractive power distribution of the variable magnification optical system ZL and the focal point from the wide-angle end state (W) to the telephoto end state (T). The state of movement of each lens group in the change of the distance state is indicated by an arrow below FIG. As shown in FIG. 1, the variable magnification optical system ZL according to the present embodiment includes a front lens group FG and a rear lens group RG in order from the object side along the optical axis. The front lens group FG includes, in order from the object side, a front partial lens group FG1 having a positive refractive power and a rear partial lens group FG2 having a negative refractive power. The rear lens group RG includes, in order from the object side, a first lens group RG1 having a positive refractive power, a second lens group RG2 having a negative refractive power, and a third lens group RG3 having a positive refractive power. Is done.

In each embodiment, the height of the aspheric surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangential plane of the apex of each aspheric surface to each aspheric surface at height y. Is S (y), r is the radius of curvature of the reference sphere (paraxial radius of curvature), κ is the conic constant, and An is the nth-order aspheric coefficient, and is expressed by the following equation (a). . In the following examples, “E−n” indicates “× 10 ⁻ⁿ ”.

S (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 (a)

  In each embodiment, the secondary aspheric coefficient A2 is zero. In the table of each example, an aspherical surface is marked with * on the left side of the surface number.

[First embodiment]
FIG. 1 is a diagram showing a configuration of a variable magnification optical system ZL1 according to the first example. The zoom optical system ZL1 in FIG. 1 includes, in order from the object side, a front partial lens group FG1 having a positive refractive power, a rear partial lens group FG2 having a negative refractive power, and a first refractive power having a positive refractive power. It includes a lens group RG1, a 2a partial lens group RG2a having a negative refractive power, a second b partial lens group RG2b having a negative refractive power, and a third lens group RG3 having a positive refractive power. In the zoom optical system ZL1, when the lens position changes from the wide-angle end state to the telephoto end state, the air gap between the front partial lens group FG1 and the rear partial lens group FG2 changes, and the rear partial lens group FG2 The air gap between the first lens group RG1 decreases, the air gap between the first lens group RG1 and the second a partial lens group RG2a changes from d12w to d12t, and the second b partial lens group RG2b, the third lens group RG3, When the camera shake occurs, the distance between the lens groups is changed so as to change from d23w to d23t, and the 2a partial lens group RG2a is moved so as to have a component orthogonal to the optical axis. The image position is corrected. Note that the distance d12w or d12t between the first lens group RG1 and the second lens group RG2 in the wide-angle end state or the telephoto end state corresponds to d3 in the table showing the values of the specifications of each example, and the wide-angle end state or The distance d23w or d23t between the second lens group RG2 and the third lens group RG3 in the telephoto end state corresponds to d4 in the table showing the values of the specifications in each example.

  The front lens group FG1 includes, in order from the object side, a cemented lens of a negative meniscus lens FL11 having a convex surface facing the object side and a positive meniscus lens FL12 having a convex surface facing the object side, and a positive lens having a convex surface facing the object side. It comprises a meniscus lens FL13. The rear partial lens group FG2 includes, in order from the object side, a negative meniscus lens FL21 having a convex surface facing the object side, a biconcave lens FL22, a biconvex lens FL23, and a negative meniscus lens FL24 having a concave surface facing the object side. The negative meniscus lens FL21 located closest to the object side of the partial lens group FG2 is a compound aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The first lens group RG1 includes, in order from the object side, a cemented lens of a negative meniscus lens RL11 and a biconvex lens RL12 having a convex surface facing the object side, and a positive meniscus lens RL13 having a convex surface facing the object side. The second-a partial lens group RG2a includes, in order from the object side, a cemented lens of a biconcave lens RL21 and a positive meniscus lens RL22 having a convex surface facing the object side, and is located on the most object side of the second-a partial lens group RG2a. The concave lens RL21 is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface. The second b partial lens group RG2b includes a negative meniscus lens RL23 having a concave surface directed toward the object side. The third lens group RG3 includes, in order from the object side, a biconvex lens RL31, and a cemented lens of the biconvex lens RL32 and a negative meniscus lens RL33 having a concave surface facing the object side, and is the most image side of the third lens group RG3. The negative meniscus lens RL33 located at is a glass mold type aspherical lens having an aspherical lens surface on the image side.

  The aperture stop S is located between the rear partial lens group FG2 and the first lens group RG1, and moves together with the first lens group RG1 upon zooming from the wide-angle end state to the telephoto end state. Focusing from a long distance to a short distance is performed by moving the rear partial lens group FG2 in the object direction.

  In addition, in a lens where the focal length of the entire system is f and the image stabilization correction coefficient (ratio of the moving amount of the image position on the imaging surface to the moving amount of the moving lens group in shake correction) is K, the rotational blurring of the angle θ is performed. In order to correct this, the moving lens group for blurring correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the wide-angle end state of the first embodiment, the image stabilization correction coefficient is 1.04, and the focal length is 18.4 (mm). Therefore, the 2a portion for correcting the rotation blur of 1.50 ° The moving amount of the lens group RG2a is 0.46 (mm). In the telephoto end state of the first embodiment, since the image stabilization correction coefficient is 1.85 and the focal length is 102.5 (mm), the second portion a for correcting the rotation blur of 0.60 °. The movement amount of the lens group RG2a is 0.58 (mm). In this embodiment, it is assumed that double rotational shake (in the range of 0 ° to 0.60 °) has occurred as compared with the normal case, and a moving lens group (first lens) for correcting rotational shake is used. The amount of movement of the 2a partial lens group RG2a) is considered as a double amount. These descriptions are the same in the following embodiments.

  Table 1 below lists values of specifications of the first embodiment. In Table 1, f represents a focal length, FNO represents an F number, ω represents a half field angle, and Bf represents a back focus. Furthermore, the surface number is the order of the lens surfaces from the object side along the direction of travel of the light beam, the surface interval is the distance on the optical axis from each optical surface to the next optical surface, and the refractive index and Abbe number are each The value for the d-line (λ = 587.6 nm) is shown. Here, “mm” is generally used for the focal length f, the radius of curvature, the surface interval, and other length units listed in all the following specifications, but the optical system is proportionally enlarged or reduced. However, since the same optical performance can be obtained, it is not limited to this. The radius of curvature of 0.0000 indicates a plane, and the refractive index of air of 1.0000 is omitted. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1)
Surface number Curvature radius Surface spacing Abbe number Refractive index
1 148.6804 1.8000 23.78 1.846660
2 53.5195 6.9847 56.45 1.672275
3 1203.8588 0.1000
4 45.7199 4.4150 48.95 1.770984
5 136.8162 (d1)
* 6 87.1098 0.2000 38.09 1.553890
7 65.0000 1.0000 50.73 1.764943
8 12.2656 6.3636
9 -29.3430 1.0000 42.62 1.833873
10 36.0783 0.6211
11 29.3049 5.2003 23.07 1.847995
12 -27.3230 1.0791
13 -19.6728 1.0028 39.93 1.833079
14 -72.9545 (d2)
15 0.0000 1.1000
16 31.0569 1.7500 23.78 1.846660
17 18.9160 4.1954 69.20 1.519000
18 -28.5216 0.2000
19 22.7713 2.4518 82.49 1.498000
20 172.4901 (d3)
* 21 -47.0722 0.1500 38.09 1.553890
22 -44.0722 1.0000 37.16 1.834000
23 14.9882 3.0239 25.43 1.805181
24 182.1551 4.8081
25 -16.4968 1.0000 43.03 1.818577
26 -34.2785 (d4)
27 61.8619 5.5935 65.57 1.538373
28 -19.6512 0.7000
29 50.3975 7.5000 70.41 1.487490
30 -15.1843 1.4000 40.78 1.806100
* 31 -55.8591 (Bf)

Wide angle end Intermediate focal length Telephoto end
f = 18.4 to 55.0 to 102.5
FNO = 3.5 to 4.7 to 5.8
ω = 38.7 to 14.0 to 7.7
Image height = 14.0 to 14.0 to 14.0
Total length = 130.936-161.050-185.048
Bf = 40.000 to 60.991 to 82.306

[Focal length of each lens group]
Lens group Start surface Focal length FG1 1 75.683
FG2 6 -12.500
RG1 15 21.900
RG2 21 -18.673
RG3 27 25.435

[Focal length of front lens group FG and rear lens group RG]
Lens group Start surface Wide angle end Intermediate focal length Telephoto end FG 1 -17.447 -28.905 -38.479
RG 15 31.603 30.660 30.261

  In the first embodiment, the lens surfaces of the sixth surface, the twenty-first surface and the thirty-first surface are formed in an aspherical shape. Table 2 below shows aspheric data, that is, the values of the conic constant κ and the aspheric constants A4 to A10.

(Table 2)
κ A4 A6 A8 A10
6th surface -46.1784 2.75110E-05 -7.34000E-08 1.31870E-10 5.44290E-14
Side 21 10.3116 2.43420E-05 2.48240E-08 0.00000E + 00 0.00000E + 00
31st surface 4.0858 1.21100E-05 -3.67070E-09 -4.27560E-11 -2.41150E-13

  In the first embodiment, the axial air distance d1 between the front partial lens group FG1 and the rear partial lens group FG2, the axial air distance d2 between the rear partial lens group FG2 and the first lens group RG1, and the first lens group RG1. The axial air gap d3 between the second lens group RG2 and the axial air gap d4 between the second lens group RG2 and the third lens group RG3 changes during zooming. Table 3 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 3)
Wide angle end Intermediate focal length Telephoto end
d1 1.814 23.307 31.451
d2 18.119 5.749 0.289
d3 2.471 4.753 5.363
d4 3.892 1.611 1.000

  Table 4 below shows values corresponding to the conditional expressions in the first embodiment. In Table 4, d12t is the distance between the first lens group RG1 and the second lens group RG2 in the telephoto end state, and d12w is the distance between the first lens group RG1 and the second lens group RG2 in the wide angle end state. d23t is the distance between the second lens group RG2 and the third lens group RG3 in the telephoto end state, d23w is the distance between the second lens group RG2 and the third lens group RG3 in the wide-angle end state, and BL is a conditional expression ( As shown in 1) to (4), the combined picture focal length fw123 of the first lens group RG1, the second lens group RG2, and the third lens group RG3, and the first lens group RG1 and the second lens in the wide-angle end state. A value obtained from the combined magnification βw123 of the lens group RG2 and the third lens group RG3, Δx1 is the first lens group RG1 when the lens position state changes from the wide-angle end state to the telephoto end state. F2 is the focal length of the second lens group RG2, fR2a is the focal length of the second a partial lens group RG2a, fR2b is the focal length of the second b partial lens group RG2b, and Rs is the second a. The radius of curvature of the cemented surface of the cemented lens of the partial lens group RG2a, Np the refractive index with respect to the d-line of the positive meniscus lens of the 2a partial lens group RG2a, and Nn with respect to the d-line of the biconcave lens of the 2a partial lens group RG2a Νp represents the refractive index, νp represents the Abbe number of the positive meniscus lens of the 2a partial lens group RG2a, and νn represents the Abbe number of the biconcave lens of the 2a partial lens group RG2a. The description of this symbol is the same in the following embodiments.

(Table 4)
(1) (d12t-d12w) /BL=0.045
(2) (d23w-d23t) /BL=0.045
(3) (d12w / d13w) = 0.151
(4) (d23t / d13t) = 0.061
(5) | Δx1 | /BL=0.652
(6) (−f2) /BL=0.288
(7) fR2a / fR2b = 1.016
(8) Rs / (− f2) = 0.803
(9) Np−Nn = −0.029
(10) νn−νp = 11.730

  FIG. 2A shows an aberration diagram in the infinite focus state in the wide-angle end state of the first embodiment, FIG. 3 shows an aberration diagram in the infinite focus state in the intermediate focal length state, and FIG. FIG. 4A shows an aberration diagram in the infinitely focused state. Further, FIG. 2B shows a meridional lateral aberration diagram when the blur correction is performed with respect to the rotational blur of 1.50 ° in the infinity photographing state at the wide-angle end state in the first embodiment. FIG. 4B shows a meridional lateral aberration diagram when blur correction is performed for 0.60 ° rotational blur in the infinity shooting state at the telephoto end state.

  In each aberration diagram, FNO represents an F number, Y represents an image height, d represents a d-line (λ = 587.6 nm), and g represents a g-line (λ = 435.6 nm). In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. The description of this aberration diagram is the same in the following examples. As is apparent from the respective aberration diagrams, in the first embodiment, it is understood that various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

[Second Embodiment]
FIG. 5 is a diagram showing a configuration of the variable magnification optical system ZL2 according to the second example. The zoom optical system ZL2 in FIG. 5 includes, in order from the object side, a front partial lens group FG1 having a positive refractive power, a rear partial lens group FG2 having a negative refractive power, and a first lens having a positive refractive power. It includes a lens group RG1, a 2a partial lens group RG2a having a negative refractive power, a second b partial lens group RG2b having a negative refractive power, and a third lens group RG3 having a positive refractive power. In the variable magnification optical system ZL2, when the lens position changes from the wide-angle end state to the telephoto end state, the air gap between the front partial lens group FG1 and the rear partial lens group FG2 changes, and the rear partial lens group FG2 The air gap between the first lens group RG1 decreases, the air gap between the first lens group RG1 and the second a partial lens group RG2a increases from d12w to d12t, and the second b partial lens group RG2b, the third lens group RG3, The distance between the lens groups is changed so that the air distance decreases from d23w to d23t, and the second-a partial lens group RG2a is moved so as to have a component in a direction orthogonal to the optical axis. Perform position correction.

  The front lens group FG1 includes, in order from the object side, a cemented lens of a negative meniscus lens FL11 having a convex surface facing the object side and a biconvex lens FL12, and a positive meniscus lens FL13 having a convex surface facing the object side. The rear partial lens group FG2 includes, in order from the object side, a negative meniscus lens FL21 having a convex surface facing the object side, a biconcave lens FL22, a biconvex lens FL23, and a negative meniscus lens FL24 having a concave surface facing the object side. The negative meniscus lens FL21 located closest to the object side of the partial lens group FG2 is a compound aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The first lens group RG1 includes, in order from the object side, a cemented lens of a negative meniscus lens RL11 and a biconvex lens RL12 having a convex surface facing the object side, and a biconvex lens RL13. The second-a partial lens group RG2a includes, in order from the object side, a cemented lens of a biconcave lens RL21 and a positive meniscus lens RL22 having a convex surface facing the object side, and is located on the most object side of the second-a partial lens group RG2a. The concave lens RL21 is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface. The second b partial lens group RG2b includes a negative meniscus lens RL23 having a concave surface directed toward the object side. The third lens group RG3 is composed of, in order from the object side, a cemented lens of a biconvex lens RL31, a biconvex lens RL32, and a negative meniscus lens RL33 with a concave surface facing the object side, and is positioned closest to the image side of the third lens group RG3. The negative meniscus lens RL33 is a glass mold type aspheric lens having an aspheric lens surface on the image side.

  The aperture stop S is located between the rear partial lens group FG2 and the first lens group RG1, and moves together with the first lens group RG1 upon zooming from the wide-angle end state to the telephoto end state. Focusing from a long distance to a short distance is performed by moving the rear partial lens group FG2 in the object direction.

  In the wide-angle end state of the second embodiment, the image stabilization correction coefficient is 1.09, and the focal length is 18.4 (mm). Therefore, the second a for correcting the rotation blur of 1.50 ° The moving amount of the partial lens group RG2a is 0.44 (mm). In the telephoto end state of the second embodiment, the image stabilization correction coefficient is 1.81, and the focal length is 102.5 (mm). The moving amount of the 2a partial lens group RG2a is 0.59 (mm).

  Table 5 below lists values of specifications of the second embodiment.

(Table 5)
Surface number Curvature radius Surface spacing Abbe number Refractive index
1 141.9672 1.8000 23.78 1.846660
2 59.7282 7.1441 63.88 1.612832
3 -804.2555 0.1000
4 48.3636 4.4150 49.99 1.753624
5 134.2879 (d1)
* 6 82.4998 0.2000 38.09 1.553890
7 67.3309 1.0000 50.68 1.765402
8 12.0115 6.3636
9 -27.7455 1.0000 37.22 1.832009
10 30.1271 0.7433
11 27.3964 5.4311 23.01 1.848138
12 -24.9508 0.8224
13 -20.1588 1.0028 37.28 1.831988
14 -77.9331 (d2)
15 0.0000 1.1000
16 25.6704 1.7500 23.78 1.846660
17 14.9708 4.0262 53.27 1.519000
18 -77.3730 0.2000
19 26.5715 2.6614 80.31 1.507189
20 -108.7086 (d3)
* 21 -48.1707 0.1500 38.09 1.553890
22 -50.0223 1.0000 37.16 1.834000
23 16.6138 2.8272 25.43 1.805181
24 142.9395 4.6000
25 -17.7429 1.0000 54.65 1.729242
26 -23.9790 (d4)
27 49.0756 5.5104 66.05 1.494951
28 -20.6592 0.2115
29 32.8049 7.1815 70.41 1.487490
30 -15.5785 1.4000 40.78 1.806100
* 31 -656.8808 (Bf)

Wide angle end Intermediate focal length Telephoto end
f = 18.4 to 55.0 to 102.5
FNO = 3.6 to 5.1 to 5.8
ω = 38.7 to 13.9 to 7.6
Image height = 14.0 to 14.0 to 14.0
Total length = 128.696 to 160.617 to 179.982
Bf = 39.591 to 61.928 to 74.550

[Focal length of each lens group]
Lens group Start surface Focal length FG1 1 77.537
FG2 6 -12.500
RG1 15 25.028
RG2 21 -27.950
RG3 27 29.989
[Focal length of front lens group FG and rear lens group RG]
Lens group Start surface Wide angle end Intermediate focal length Telephoto end FG 1 -17.198 -28.191 -42.380
RG 15 29.655 29.105 28.925

  In the second embodiment, the lens surfaces of the sixth surface, the twenty-first surface, and the thirty-first surface are formed in an aspherical shape. Table 6 below shows the aspheric data, that is, the values of the conic constant κ and the aspheric constants A4 to A10.

(Table 6)
κ A4 A6 A8 A10
6th surface 14.0947 1.46960E-05 -6.48040E-08 1.01710E-10 -3.11160E-14
Side 21 0.9876 1.37770E-05 -2.43220E-08 0.00000E + 00 0.00000E + 00
31st surface 674.6493 1.01750E-05 -3.17940E-08 4.90920E-11 -9.15600E-13

  In the second embodiment, the axial air gap d1 between the front partial lens group FG1 and the rear partial lens group FG2, the axial air gap d2 between the rear partial lens group FG2 and the first lens group RG1, and the first lens group RG1. The axial air gap d3 between the second lens group RG2 and the axial air gap d4 between the second lens group RG2 and the third lens group RG3 changes during zooming. Table 7 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 7)
Wide angle end Intermediate focal length Telephoto end
d1 1.805 23.781 35.292
d2 17.359 4.967 0.200
d3 2.400 4.774 5.300
d4 3.900 1.526 1.000

  Table 8 below shows values corresponding to the conditional expressions in the second embodiment.

(Table 8)
(1) (d12t-d12w) /BL=0.047
(2) (d23w−d23t) /BL=0.047
(3) (d12w / d13w) = 0.151
(4) (d23t / d13t) = 0.063
(5) | Δx1 | /BL=0.570
(6) (−f2) /BL=0.455
(7) fR2a / fR2b = 0.403
(8) Rs / (− f2) = 0.594
(9) Np−Nn = −0.029
(10) νn−νp = 11.730

  FIG. 6A is an aberration diagram in the infinite focus state in the wide-angle end state of FIG. 6A, FIG. 7 is an aberration diagram in the infinite focus state in the intermediate focal length state, and FIG. FIG. 8A shows an aberration diagram of the in-focus state at infinity. FIG. 6B shows a meridional lateral aberration diagram when the blur correction is performed for the rotational blur of 1.50 ° in the infinity photographing state at the wide-angle end state of the second embodiment. FIG. 8B shows a meridional lateral aberration diagram when blur correction is performed for 0.60 ° rotation blur in the infinity shooting state at the telephoto end state. As is apparent from the respective aberration diagrams, in the second example, it is understood that various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

[Third embodiment]
FIG. 9 is a diagram illustrating a configuration of the variable magnification optical system ZL3 according to the third example. This third embodiment is shown as a reference example. The zoom optical system ZL3 in FIG. 9 includes, in order from the object side, a front partial lens group FG1 having a positive refractive power, a rear partial lens group FG2 having a negative refractive power, and a first refractive power having a positive refractive power. The lens group RG1 includes a second lens group RG2 having a negative refractive power, and a third lens group RG3 having a positive refractive power. In the variable magnification optical system ZL2, when the lens position changes from the wide-angle end state to the telephoto end state, the air gap between the front partial lens group FG1 and the rear partial lens group FG2 increases, and the rear partial lens group FG2 The air gap between the first lens group RG1 decreases, the air gap between the first lens group RG1 and the second lens group RG2 increases from d12w to d12t, and the air between the second lens group RG2 and the third lens group RG3. The distance between the lens groups changes so that the distance decreases from d23w to d23t, and the second lens group RG2 is moved so as to have a component orthogonal to the optical axis, thereby correcting the image position when camera shake occurs. .

  The front lens group FG1 includes, in order from the object side, a cemented lens of a negative meniscus lens FL11 having a convex surface facing the object side and a biconvex lens FL12, and a positive meniscus lens FL13 having a convex surface facing the object side. The rear partial lens group FG2 includes, in order from the object side, a negative meniscus lens FL21 having a convex surface directed toward the object side, a biconcave lens FL22, a biconvex lens FL23, and a biconcave lens FL24, and is the most object side of the rear partial lens group FG2. The negative meniscus lens FL21 located at is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The first lens group RG1 includes, in order from the object side, a cemented lens of a negative meniscus lens RL11 and a biconvex lens RL12 having a convex surface facing the object side, and a biconvex lens RL13. The second lens group RG2 includes, in order from the object side, a cemented lens of a biconcave lens RL21 and a positive meniscus lens RL22 having a convex surface facing the object side. The biconcave lens RL21 located closest to the object side of the second lens group RG2. Is a glass mold type aspheric lens having an aspheric lens surface on the object side. The third lens group RG3 includes, in order from the object side, a negative meniscus lens RL31 having a concave surface facing the object side, a biconvex lens RL32, and a cemented lens of a biconvex lens RL33 and a negative meniscus lens RL34 having a concave surface facing the object side. The second biconvex positive lens RL32 configured from the object side of the third lens group RG3 is a glass mold type aspheric lens having an aspheric lens surface on the image side.

  The aperture stop S is located between the rear partial lens group FG2 and the first lens group RG1, and moves together with the first lens group RG1 upon zooming from the wide-angle end state to the telephoto end state. The flare stop FS is located between the second lens group RG2 and the third lens group RG3, and moves together with the second lens group RG2 upon zooming from the wide-angle end state to the telephoto end state. Focusing from a long distance to a short distance is performed by moving the rear partial lens group FG2 in the object direction.

  In the wide angle end state of the third embodiment, the image stabilization correction coefficient is 1.36 and the focal length is 18.4 (mm). Therefore, the second correction for correcting the 1.50 degree rotational shake is performed. The moving amount of the lens group RG2 is 0.35 (mm). Further, in the telephoto end state of the third embodiment, the image stabilization correction coefficient is 2.07 and the focal length is 102.5 (mm), so that the rotational shake of 0.60 ° is corrected. The movement amount of the second lens group RG2 is 0.52 (mm).

  Table 9 below lists values of specifications of the third example.

(Table 9)
Surface number Curvature radius Surface spacing Abbe number Refractive index
1 168.5241 1.8000 23.78 1.846660
2 63.9191 7.2344 60.67 1.603110
3 -300.0632 0.1000
4 46.7411 4.4000 55.52 1.696800
5 136.3067 (d1)
* 6 103.2719 0.2000 38.09 1.553890
7 90.0000 1.2500 42.72 1.834810
8 11.9191 5.6078
9 -56.6965 1.0000 42.72 1.834810
10 30.5436 0.3053
11 21.3769 5.4731 23.78 1.846660
12 -30.9544 0.3000
13 -25.6945 1.0000 42.72 1.834810
14 127.3435 (d2)
15 0.0000 0.4000
16 26.9094 1.0000 25.43 1.805180
17 14.3402 4.1000 64.11 1.516800
18 -54.4001 0.2000
19 28.1865 2.7770 82.56 1.497820
20 -48.6011 (d3)
* 21 -42.8743 1.0000 40.94 1.806100
22 15.6173 2.4000 23.78 1.846660
23 61.0904 3.0000 1.000000
24 0.0000 (d4)
25 -18.2298 1.0000 70.40 1.487490
26 -33.1351 0.1000
27 53.1321 5.8599 61.18 1.589130
* 28 -19.8760 0.5000
29 49.8623 7.2500 70.44 1.487490
30 -15.8905 1.4000 34.96 1.801000
31 -831.5220 (Bf)

Wide angle end Intermediate focal length Telephoto end
f = 18.4 to 54.0 to 102.5
FNO = 3.7 to 5.1 to 5.9
ω = 38.6 to 14.0 to 7.6
Image height = 14.0 to 14.0 to 14.0
Total length = 131.999 to 158.787 to 176.078
Bf = 38.400 to 56.889 to 67.200

[Focal length of each lens group]
Lens group Start surface Focal length FG1 1 76.048
FG2 6 -12.255
RG1 15 22.167
RG2 21 -32.817
RG3 25 41.054

[Focal length of front lens group FG and rear lens group RG]
Lens group Start surface Wide angle end Intermediate focal length Telephoto end FG 1 -16.844 -27.345 -41.734
RG 15 30.713 29.022 28.174

  In the third embodiment, the lens surfaces of the sixth surface, the twenty-first surface, and the twenty-eighth surface are formed in an aspherical shape. Table 10 below shows the aspheric data, that is, the values of the conic constant κ and the aspheric constants A4 to A10.

(Table 10)
κ A4 A6 A8 A10
6th surface 24.2949 2.55426E-06 -2.76351E-08 2.37730E-11 -3.74852E-14
Side 21 -4.6845 -3.66407E-06 2.99667E-08 0.00000E + 00 0.00000E + 00
28th surface 0.9199 1.18820E-05 1.03377E-08 1.69107E-11 -4.18115E-13

  In the third example, the axial air gap d1 between the front partial lens group FG1 and the rear partial lens group FG2, the axial air gap d2 between the rear partial lens group FG2 and the first lens group RG1, and the first lens group RG1. The axial air gap d3 between the second lens group RG2 and the axial air gap d4 between the second lens group RG2 and the third lens group RG3 changes during zooming. Table 11 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 11)
Wide angle end Intermediate focal length Telephoto end
d1 1.790 23.037 34.787
d2 20.718 7.770 3.000
d3 2.032 6.185 7.782
d4 9.402 5.249 3.652

  Table 12 below shows values corresponding to the conditional expressions in the third embodiment. In the third example, the 2a partial lens RG2a in the conditional expressions (8) to (10) corresponds to the second lens group RG2, and Rs is the curvature of the cemented surface of the cemented lens of the second lens group RG2. Np is the refractive index with respect to the d-line of the positive meniscus lens of the second lens group RG2, Nn is the refraction with respect to the d-line of the biconcave lens of the second lens group RG2, and νp is the positive meniscus lens of the second lens group RG2. Νn represents the Abbe number of the biconcave lens of the second lens group RG2.

(Table 12)
(1) (d12t-d12w) /BL=0.089
(2) (d23w−d23t) /BL=0.089
(3) (d12w / d13w) = 0.114
(4) (d23t / d13t) = 0.205
(5) | Δx1 | /BL=0.448
(6) (−f2) /BL=0.511
(7) fR2a / fR2b = (none)
(8) Rs / (− f2) = 0.476
(9) Np-Nn = 0.041
(10) νn−νp = 17.160

  FIG. 10A shows an aberration diagram in the infinite focus state in the wide-angle end state of this third embodiment, FIG. 11 shows an aberration diagram in the infinite focus state in the intermediate focal length state, and FIG. FIG. 12A shows an aberration diagram in the infinitely focused state. FIG. 10B shows a meridional lateral aberration diagram when the blur correction is performed for the rotational blur of 1.50 ° in the infinite distance photographing state at the wide-angle end state of the third example. FIG. 12B shows a meridional lateral aberration diagram when the blur correction for the 0.60 ° rotational blur is performed in the infinity photographing state at the telephoto end state. As is apparent from the respective aberration diagrams, in the third example, it is understood that various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

[Fourth embodiment]
FIG. 13 is a diagram showing a configuration of the variable magnification optical system ZL4 according to the fourth example. The variable magnification optical system ZL4 in FIG. 13 includes, in order from the object side, a front partial lens group FG1 having a positive refractive power, a rear partial lens group FG2 having a negative refractive power, and a first partial lens having a positive refractive power. It includes a lens group RG1, a 2a partial lens group RG2a having a negative refractive power, a second b partial lens group RG2b having a negative refractive power, and a third lens group RG3 having a positive refractive power. In the zoom optical system ZL4, when the lens position changes from the wide-angle end state to the telephoto end state, the air interval between the front partial lens group FG1 and the rear partial lens group FG2 changes, and the rear partial lens group FG2 The air gap between the first lens group RG1 decreases, the air gap between the first lens group RG1 and the second a partial lens group RG2a increases from d12w to d12t, and the second b partial lens group RG2b, the third lens group RG3, The distance between the lens groups is changed so that the air distance decreases from d23w to d23t, and the 2a partial lens group RG2a is moved so as to have a component in the direction orthogonal to the optical axis. Make corrections.

  The front lens group FG1 includes, in order from the object side, a cemented lens of a negative meniscus lens FL11 having a convex surface facing the object side and a positive meniscus lens FL12 having a convex surface facing the object side, and a positive lens having a convex surface facing the object side. It comprises a meniscus lens FL13. The rear partial lens group FG2 includes, in order from the object side, a negative meniscus lens FL21 having a convex surface facing the object side, a biconcave lens FL22, a biconvex lens FL23, and a negative meniscus lens FL24 having a concave surface facing the object side. The negative meniscus lens FL21 located closest to the object side of the partial lens group FG2 is a compound aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The first lens group RG1 includes, in order from the object side, a cemented lens of a negative meniscus lens RL11 and a biconvex lens RL12 having a convex surface facing the object side, and a biconvex lens RL13. The second-a partial lens group RG2a includes, in order from the object side, a cemented lens of a biconcave lens RL21 and a positive meniscus lens RL22 having a convex surface facing the object side, and is located on the most object side of the second-a partial lens group RG2a. The concave lens RL21 is a glass mold type aspheric lens having an aspheric lens surface on the object side. The second b partial lens group RG2b includes a negative meniscus lens RL23 having a concave surface directed toward the object side. The third lens group RG3 includes, in order from the object side, a biconvex lens RL31, and a cemented lens of the biconvex lens RL32 and a negative meniscus lens RL33 having a concave surface facing the object side, and is the most object side of the third lens group RG3. The biconvex lens RL31 located at is a glass mold type aspheric lens having an aspherical lens surface on the image side.

  The aperture stop S is located between the rear partial lens group FG2 and the first lens group RG1, and moves together with the first lens group RG1 upon zooming from the wide-angle end state to the telephoto end state. Focusing from a long distance to a short distance is performed by moving the rear partial lens group FG2 in the object direction.

  In the fourth embodiment, in the wide-angle end state, the image stabilization correction coefficient is 0.96 and the focal length is 18.4 (mm), so that the second 2a for correcting the rotation blur of 1.50 ° is used. The moving amount of the partial lens group RG2a is 0.50 (mm). Further, in the telephoto end state of the fourth embodiment, the image stabilization correction coefficient is 1.69 and the focal length is 131.2 (mm), so that it is necessary to correct the rotation blur of 0.60 °. The moving amount of the second a partial lens group RG2a is 0.81 (mm).

  Table 13 below provides values of specifications of the fourth example.

(Table 13)
Surface number Curvature radius Surface spacing Abbe number Refractive index
1 112.1569 1.8000 23.78 1.846660
2 58.9628 6.8193 65.36 1.603576
3 134933.2300 0.1000
4 46.6226 4.4150 58.17 1.656160
5 126.2737 (d1)
* 6 79.1072 0.2000 38.09 1.553890
7 65.0000 1.2500 41.28 1.833557
8 12.4412 6.3645
9 -30.7007 1.0000 37.30 1.832041
10 37.1726 0.5656
11 28.6372 5.0654 21.89 1.851566
12 -27.5478 0.8229
13 -19.8405 1.0028 42.62 1.833884
14 -83.9641 (d2)
15 0.0000 0.4000
16 33.4879 1.7500 23.78 1.846660
17 19.6805 4.1226 69.81 1.520350
18 -30.3359 0.2000
19 24.3031 2.5692 82.50 1.498000
20 -507.4183 (d3)
* 21 -63.2689 1.0600 42.51 1.834032
22 21.8379 2.3208 23.80 1.846000
23 90.2702 4.6000
24 -15.3335 1.0000 54.66 1.729157
25 -27.1645 (d4)
26 97.9379 5.6102 63.18 1.536981
* 27 -16.7260 0.2000
28 54.2066 6.4592 64.41 1.513811
29 -15.9610 1.4000 35.86 1.837905
30 -160.0000 (Bf)

Wide angle end Intermediate focal length Telephoto end
f = 18.4 to 56.3 to 131.2
FNO = 3.7 to 5.1 to 5.8
ω = 38.7 to 13.7 to 6.0
Image height = 14.0 to 14.0 to 14.0
Total length = 127.748 to 159.282 to 185.685
Bf = 39.272 to 60.150 to 77.217

[Focal length of each lens group]
Lens group Start surface Focal length FG1 1 80.846
FG2 6 -12.289
RG1 15 21.900
RG2 21 -22.542
RG3 26 29.108

[Focal length of front lens group FG and rear lens group RG]
Lens group Start surface Wide angle end Intermediate focal length Telephoto end FG 1 -16.892 -27.528 -47.980
RG 15 30.011 28.413 27.845

  In the fourth embodiment, the lens surfaces of the sixth surface, the twenty-first surface, and the twenty-seventh surface are formed in an aspherical shape. Table 14 below shows the aspheric data, that is, the values of the conic constant κ and the aspheric constants A4 to A10.

(Table 14)
κ A4 A6 A8 A10
6th surface 24.8303 9.11840E-06 -6.69300E-08 1.74540E-10 -5.56370E-13
Side 21 -0.4549 4.72520E-06 -8.61830E-09 0.00000E + 00 0.00000E + 00
27th surface 0.3588 -4.67110E-07 -1.27860E-09 -1.10550E-10 -8.78330E-14

  In the fourth example, the axial air gap d1 between the front partial lens group FG1 and the rear partial lens group FG2, the axial air gap d2 between the rear partial lens group FG2 and the first lens group RG1, and the first lens group RG1. The axial air gap d3 between the second lens group RG2 and the axial air gap d4 between the second lens group RG2 and the third lens group RG3 changes during zooming. Table 15 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 15)
Wide angle end Intermediate focal length Telephoto end
d1 1.749 24.474 39.858
d2 18.616 6.547 0.500
d3 2.200 5.386 6.213
d4 4.813 1.627 0.800

  Table 16 below shows values corresponding to the conditional expressions in the fourth embodiment.

(Table 16)
(1) (d21t-d21w) /BL=0.064
(2) (d23w-d23t) /BL=0.064
(3) (d12w / d13w) = 0.138
(4) (d23t / d13t) = 0.050
(5) | Δx1 | /BL=0.605
(6) (−f2) /BL=0.360
(7) fR2a / fR2b = 0.899
(8) Rs / (− f2) = 0.969
(9) Np-Nn = 0.012
(10) νn−νp = 18.710

  FIG. 14A shows an aberration diagram in the infinite focus state in the wide-angle end state of this fourth embodiment, FIG. 15 shows an aberration diagram in the infinite focus state in the intermediate focal length state, and FIG. FIG. 16A shows an aberration diagram of the infinitely focused state. Further, FIG. 14B shows a meridional lateral aberration diagram when the blur correction is performed with respect to the rotational blur of 1.50 ° in the infinity photographing state at the wide-angle end state of the fourth example. FIG. 16B shows a meridional lateral aberration diagram when blur correction is performed with respect to 0.60 ° rotation blur in the infinity shooting state at the telephoto end state. As is apparent from the respective aberration diagrams, in the fourth example, it is understood that various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

[Fifth embodiment]
FIG. 17 is a diagram showing a configuration of a variable magnification optical system ZL5 according to the fifth example. The zoom optical system ZL5 in FIG. 17 includes, in order from the object side, a front partial lens group FG1 having a positive refractive power, a rear partial lens group FG2 having a negative refractive power, and a first refractive power having a first refractive power. It includes a lens group RG1, a 2a partial lens group RG2a having a negative refractive power, a second b partial lens group RG2b having a negative refractive power, and a third lens group RG3 having a positive refractive power. In the variable magnification optical system ZL5, when the lens position changes from the wide-angle end state to the telephoto end state, the air gap between the front partial lens group FG1 and the rear partial lens group FG2 changes, and the rear partial lens group FG2 The air gap between the first lens group RG1 decreases, the air gap between the first lens group RG1 and the second a partial lens group RG2a increases from d12w to d12t, and the second b partial lens group RG2b, the third lens group RG3, The distance between the lens groups is changed so that the air distance decreases from d23w to d23t, and the 2a partial lens group RG2a is moved so as to have a component in the direction orthogonal to the optical axis. Make corrections.

  The front lens group FG1 includes, in order from the object side, a cemented lens of a negative meniscus lens FL11 having a convex surface facing the object side and a positive meniscus lens FL12 having a convex surface facing the object side, and a positive lens having a convex surface facing the object side. It comprises a meniscus lens FL13. The rear partial lens group FG2 includes, in order from the object side, a negative meniscus lens FL21 having a convex surface facing the object side, a biconcave lens FL22, a biconvex lens FL23, and a negative meniscus lens FL24 having a concave surface facing the object side. The negative meniscus lens FL21 located closest to the object side of the partial lens group FG2 is a compound aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The first lens group RG1 includes, in order from the object side, a cemented lens of a negative meniscus lens RL11 and a biconvex lens RL12 having a convex surface facing the object side, and a positive meniscus lens RL13 having a convex surface facing the object side. The second-a partial lens group RG2a includes, in order from the object side, a cemented lens of a biconcave lens RL21 and a positive meniscus lens RL22 having a convex surface facing the object side, and is located on the most object side of the second-a partial lens group RG2a. The concave lens RL21 is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface. The second b partial lens group RG2b includes a negative meniscus lens RL23 having a concave surface directed toward the object side. The third lens group RG3 includes, in order from the object side, a biconvex lens RL31, and a cemented lens of the biconvex lens RL32 and a negative meniscus lens RL33 having a concave surface facing the object side, and is the most image side of the third lens group RG3. The negative meniscus lens RL33 located at is a glass mold type aspheric lens having an aspheric surface on the image side.

  The aperture stop S is located between the rear partial lens group FG2 and the first lens group RG1, and moves together with the first lens group RG1 upon zooming from the wide-angle end state to the telephoto end state. Focusing from a long distance to a short distance is performed by moving the rear partial lens group FG2 in the object direction.

  In the wide angle end state of the fifth embodiment, the image stabilization correction coefficient is 1.01 and the focal length is 16.4 (mm), so that the second 2a for correcting the rotation blur of 1.50 ° is used. The moving amount of the partial lens group RG2a is 0.43 (mm). In the telephoto end state of the fifth embodiment, the image stabilization correction coefficient is 1.81, and the focal length is 102.0 (mm). The moving amount of the 2a partial lens group RG2a is 0.59 (mm).

  Table 17 below provides values of specifications of the fifth example.

(Table 17)
Surface number Curvature radius Surface spacing Abbe number Refractive index
1 153.8859 1.8000 23.78 1.846660
2 57.0964 7.0870 61.28 1.630009
3 3646.5256 0.1000
4 48.8123 4.4150 46.65 1.815470
5 138.1872 (d1)
* 6 99.0907 0.2000 38.09 1.553890
7 69.8084 1.0000 44.24 1.825495
8 11.3523 6.3636
9 -26.7608 1.0000 42.60 1.834000
10 37.8660 0.5309
11 29.7415 5.0776 22.93 1.848386
12 -24.9665 0.8398
13 -20.4861 1.0028 37.93 1.832305
14 -62.1035 (d2)
15 0.0000 1.1000
16 28.8737 1.7500 23.78 1.846660
17 17.2050 4.1402 59.42 1.519000
18 -28.5208 0.2000
19 22.7031 2.3510 82.49 1.498000
20 150.0469 (d3)
* 21 -41.4874 0.1500 38.09 1.553890
22 -36.4874 1.0000 37.16 1.834000
23 15.4285 3.0254 25.43 1.805181
24 480.3477 4.5000
25 -19.6899 1.0000 40.29 1.820865
26 -51.7953 (d4)
27 39.2092 5.9232 69.65 1.494313
28 -19.8633 0.6672
29 41.5729 7.0735 70.41 1.487490
30 -15.2714 1.4000 40.78 1.806100
* 31 -67.9910 (Bf)

Wide angle end Intermediate focal length Telephoto end
f = 16.4 to 55.0 to 102.0
FNO = 3.6 to 5.1 to 5.8
ω = 42.0 to 13.9 to 7.7
Image height = 14.0 to 14.0 to 14.0
Total length = 128.338 to 164.176 to 186.292
Bf = 38.199 to 62.873 to 78.620

[Focal length of each lens group]
Lens group Start surface Focal length FG1 1 80.125
FG2 6 -12.100
RG1 15 21.900
RG2 21 -18.488
RG3 27 24.700

[Focal length of front lens group FG and rear lens group RG]
Lens group Start surface Wide angle end Intermediate focal length Telephoto end FG 1 -16.109 -27.263 -39.344
RG 15 31.004 30.007 29.700

  In the fifth embodiment, the lens surfaces of the sixth surface, the twenty-first surface, and the thirty-first surface are aspherical. Table 18 below shows aspheric data, that is, the values of the conic constant κ and the aspheric constants A4 to A10.

(Table 18)
κ A4 A6 A8 A10
6th surface -157.1928 4.52590E-05 -2.08030E-07 7.04390E-10 -1.27000E-12
Side 21 9.3216 3.11160E-05 3.26730E-08 0.00000E + 00 0.00000E + 00
31st surface -1.2227 1.38530E-05 6.33000E-09 -1.41840E-10 1.56520E-13

  In the fifth embodiment, the axial air gap d1 between the front partial lens group FG1 and the rear partial lens group FG2, the axial air gap d2 between the rear partial lens group FG2 and the first lens group RG1, and the first lens group RG1. The axial air gap d3 between the second lens group RG2 and the axial air gap d4 between the second lens group RG2 and the third lens group RG3 changes during zooming. Table 19 below shows variable intervals at each focal length in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 19)
Wide angle end Intermediate focal length Telephoto end
d1 1.709 26.331 37.251
d2 18.207 4.749 0.200
d3 2.525 5.050 5.525
d4 4.000 1.475 1.000

  Table 20 below shows values corresponding to the conditional expressions in the fifth embodiment.

(Table 20)
(1) (d12t-d12w) /BL=0.048
(2) (d23w-d23t) /BL=0.048
(3) (d12w / d13w) = 0.156
(4) (d23t / d13t) = 0.062
(5) | Δx1 | /BL=0.646
(6) (−f2) /BL=0.295
(7) fR2a / fR2b = 1.032
(8) Rs / (− f2) = 0.835
(9) Np−Nn = −0.029
(10) νn−νp = 11.730

  FIG. 18A shows an aberration diagram in the infinite focus state in the wide-angle end state of this fifth embodiment, FIG. 19 shows an aberration diagram in the infinite focus state in the intermediate focal length state, and FIG. FIG. 20A shows an aberration diagram of the infinitely focused state. Further, FIG. 18B shows a meridional lateral aberration diagram when the blur correction is performed for the rotational blur of 1.50 ° in the infinity photographing state at the wide-angle end state of the fifth example, and FIG. FIG. 20B shows a meridional lateral aberration diagram when blur correction is performed for 0.60 ° rotational blur in the infinity shooting state at the telephoto end state. As is apparent from each aberration diagram, in the fifth example, it is understood that various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

It is sectional drawing which shows the structure of the variable magnification optical system by 1st Example. FIG. 2A is a diagram illustrating various aberrations in the infinitely focused state according to the first example, FIG. 3A is a diagram illustrating various aberrations in a wide-angle end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. FIG. 6 is an aberration diagram in an infinitely focused state at an intermediate focal length state in the first example. FIG. 4A is a diagram illustrating various aberrations in an infinitely focused state according to the first embodiment, FIG. 6A is a diagram illustrating various aberrations in a telephoto end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. It is sectional drawing which shows the structure of the variable magnification optical system by 2nd Example. FIG. 6A is a diagram illustrating various aberrations in the infinitely focused state according to the second embodiment, FIG. 5A is a diagram illustrating various aberrations in the wide-angle end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. It is an aberration diagram of the infinite focus state in the intermediate focal length state of the second embodiment. FIG. 7A is a diagram illustrating various aberrations in the infinitely focused state according to the second example, FIG. 9A is a diagram illustrating various aberrations in the telephoto end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. It is sectional drawing which shows the structure of the variable magnification optical system by 3rd Example. FIG. 4A is a diagram illustrating various aberrations in an infinitely focused state according to the third example, FIG. 4A is a diagram illustrating various aberrations in a wide-angle end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. It is an aberration diagram of the infinite focus state in the intermediate focal length state of the third embodiment. FIG. 7A is a diagram illustrating various aberrations in the infinite focus state according to the third example, FIG. 9A is a diagram illustrating various aberrations in the telephoto end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. It is sectional drawing which shows the structure of the variable magnification optical system by 4th Example. FIG. 9A is a diagram illustrating various aberrations in the infinitely focused state according to the fourth example, FIG. 9A is a diagram illustrating various aberrations in the wide-angle end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. FIG. 10 is an aberration diagram in an infinitely focused state at an intermediate focal length state in the fourth example. FIG. 9A is a diagram illustrating various aberrations in the infinitely focused state according to the fourth example, FIG. 10A is a diagram illustrating various aberrations in the telephoto end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. It is sectional drawing which shows the structure of the variable magnification optical system by 5th Example. FIG. 6A is a diagram illustrating various aberrations in the infinitely focused state according to the fifth example, FIG. 5A is a diagram illustrating various aberrations in the wide-angle end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. FIG. 10 is an aberration diagram in an infinitely focused state at an intermediate focal length state in the fifth example. FIG. 7A is a diagram illustrating various aberrations in the infinite focus state according to the fifth example, FIG. 9A is a diagram illustrating various aberrations in the telephoto end state, and FIG. FIG. 6 is a meridional transverse aberration diagram when shake correction is performed for rotational shake. The electronic still camera which mounts the variable magnification optical system which concerns on this invention is shown, (a) is a front view, (b) is a rear view. It is sectional drawing along the AA 'line of Fig.21 (a).

Explanation of symbols

ZL (ZL1 to ZL5) Variable magnification optical system FG Front lens group FG1 Front partial lens group FG2 Rear partial lens group RG Rear lens group RG1 First lens group RG2 Second lens group RG2a 2a partial lens group RG2b 2b partial lens group RG3 Third lens group S Aperture stop 1 Electronic still camera (optical equipment)

Claims (22)

Along the optical axis, from the object side,
It consists of a front lens group and a rear lens group.
The front lens group is in order from the object side.
Front lens group,
It consists of a rear lens group,
The rear lens group, in order from the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having a positive refractive power, substantially consisting of five lens groups as a whole,
When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group changes, and the distance between the first lens group and the second lens group is d12w. The distance between the second lens group and the third lens group decreases from d23w to d23t, and the distance between the front lens group and the rear lens group of the front lens group changes. And
The second lens group is in order from the object side.
A 2a partial lens group having negative refractive power;
A 2b partial lens group having negative refractive power,
Either one of the second a partial lens group or the second b partial lens group is configured to be movable so as to have a component in a direction perpendicular to the optical axis,
The 2a partial lens group is composed of a cemented lens in which, in order from the object side, a biconcave lens and a positive meniscus lens having a convex surface facing the object side are cemented,
The combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group, the second lens group, and the third lens in the wide-angle end state are set. The combined magnification with the group is βw123, the refractive index of the positive meniscus lens of the 2a partial lens group with respect to the d line is Np, and the refractive index of the 2a partial lens group with respect to the d line of the biconcave lens is Nn . Then, the following formula 0.002 <(d12t−d12w) /BL≦0.064
0.002 <(d23w-d23t) / BL <0.090
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
Variable magnification optical system that satisfies the above conditions. Along the optical axis, from the object side,
It consists of a front lens group and a rear lens group.
The front lens group is in order from the object side.
Front lens group,
It consists of a rear lens group,
The rear lens group, in order from the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having a positive refractive power, substantially consisting of five lens groups as a whole,
When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group changes, and the distance between the first lens group and the second lens group is d12w. The distance between the second lens group and the third lens group decreases from d23w to d23t, and the distance between the front lens group and the rear lens group of the front lens group changes. And
The second lens group is in order from the object side.
A 2a partial lens group having negative refractive power;
A 2b partial lens group having negative refractive power,
Either one of the second a partial lens group or the second b partial lens group is configured to be movable so as to have a component in a direction perpendicular to the optical axis,
The 2a partial lens group is composed of a cemented lens in which, in order from the object side, a biconcave lens and a positive meniscus lens having a convex surface facing the object side are cemented,
The combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group, the second lens group, and the third lens in the wide-angle end state are set. The combined magnification with the group is βw123, the refractive index of the positive meniscus lens of the 2a partial lens group with respect to the d line is Np, and the refractive index of the 2a partial lens group with respect to the d line of the biconcave lens is Nn . Then, the following formula 0.002 <(d12t−d12w) / BL <0.110
0.002 <(d23w−d23t) /BL≦0.064
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
Variable magnification optical system that satisfies the above conditions. Along the optical axis, from the object side,
It consists of a front lens group and a rear lens group.
The front lens group is in order from the object side.
Front lens group,
It consists of a rear lens group,
The rear lens group, in order from the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having a positive refractive power, substantially consisting of five lens groups as a whole,
When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group changes, and the distance between the first lens group and the second lens group is d12w. The distance between the second lens group and the third lens group decreases from d23w to d23t, and the distance between the front lens group and the rear lens group of the front lens group changes. And
The second lens group is in order from the object side.
A 2a partial lens group having negative refractive power;
A 2b partial lens group having negative refractive power,
Either one of the second a partial lens group or the second b partial lens group is configured to be movable so as to have a component in a direction perpendicular to the optical axis,
The 2a partial lens group is composed of a cemented lens in which, in order from the object side, a biconcave lens and a positive meniscus lens having a convex surface facing the object side are cemented,
The combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group, the second lens group, and the third lens in the wide-angle end state are set. The combined magnification with the group is βw123, the distance between the first lens group and the third lens group in the wide-angle end state is d13w, and the first lens group and the third lens group in the telephoto end state are When the interval is d13t, the refractive index for the d-line of the positive meniscus lens of the 2a partial lens group is Np, and the refractive index for the d-line of the biconcave lens of the 2a partial lens group is Nn, 0.002 <(d12t-d12w) / BL <0.110
0.002 <(d23w-d23t) / BL <0.090
0.010 <(d12w / d13w) <0.400
0.050 ≦ (d23t / d13t) <0.400
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
Variable magnification optical system that satisfies the above conditions. Along the optical axis, from the object side,
It consists of a front lens group and a rear lens group.
The front lens group is in order from the object side.
Front lens group,
It consists of a rear lens group,
The rear lens group, in order from the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having a positive refractive power, substantially consisting of five lens groups as a whole,
When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group changes, and the distance between the first lens group and the second lens group is d12w. The distance between the second lens group and the third lens group decreases from d23w to d23t, and the distance between the front lens group and the rear lens group of the front lens group changes. And
The second lens group is in order from the object side.
A 2a partial lens group having negative refractive power;
A 2b partial lens group having negative refractive power,
Either one of the second a partial lens group or the second b partial lens group is configured to be movable so as to have a component in a direction perpendicular to the optical axis,
The 2a partial lens group is composed of a cemented lens in which, in order from the object side, a biconcave lens and a positive meniscus lens having a convex surface facing the object side are cemented,
The combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group, the second lens group, and the third lens in the wide-angle end state are set. When the combined magnification with the group is βw123, and the amount of movement of the first lens group with respect to the image plane when the lens position changes from the wide-angle end state to the telephoto end state is Δx1, the following expression 0.002 <(d12t -D12w) / BL <0.110
0.002 <(d23w-d23t) / BL <0.090
0.440 <| Δx1 | / BL <1.00
However, BL = fw123 × (1-βw123)
Variable magnification optical system that satisfies the above conditions. When the distance between the first lens group and the third lens group in the wide-angle end state is d13w, and the distance between the first lens group and the third lens group in the telephoto end state is d13t, 0.010 <(d12w / d13w) <0.400
0.010 <(d23t / d13t) <0.400
The zoom optical system according to claim 1, wherein the zoom lens system satisfies the following condition. When the refractive index with respect to the d-line of the positive meniscus lens of the 2a partial lens group is Np, and the refractive index with respect to the d-line of the biconcave lens of the 2a partial lens group is Nn, the following formula −0.150 < Np-Nn <0.150
The zoom optical system according to claim 4 , which satisfies the following condition. The amount of movement of the first lens group relative to the image plane when the lens position changes from the wide-angle end state to the telephoto end state is Δx1, and the first lens group, the second lens group, and the third lens in the wide-angle end state. When the combined focal length with the lens group is fw123 and the combined magnification of the first lens group, the second lens group, and the third lens group in the wide-angle end state is βw123, the following expression 0.300 <| Δx1 | / BL <1.000
However, BL = fw123 × (1-βw123)
The variable magnification optical system as described in any one of Claims 1-3 which satisfy | fills these conditions. The focal length of the second lens group is f2, the combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens in the wide-angle end state is When the combined magnification of the lens group, the second lens group, and the third lens group is βw123, the following expression 0.050 <(− f2) / BL <0.900
However, BL = fw123 × (1-βw123)
The variable magnification optical system as described in any one of Claims 1-7 which satisfies these conditions. The second-a partial lens group is movable so as to have a component perpendicular to the optical axis;
Furthermore, when the focal length of the 2a partial lens group is fR2a and the focal length of the 2b partial lens group is fR2b, the following expression 0.050 <fR2a / fR2b <3,000.
The variable magnification optical system as described in any one of Claims 1-8 which satisfy | fills these conditions. When the radius of curvature of the cemented surface of the cemented lens of the 2a partial lens group is Rs and the focal length of the second lens group is f2, the following formula 0.200 <Rs / (− f2) <3,000.
The variable magnification optical system as described in any one of Claims 1-9 which satisfies these conditions. When the Abbe number of the biconcave lens in the 2a partial lens group is νn and the Abbe number of the positive meniscus lens in the 2a partial lens group is νp, the following formula is 5.000 <νn−νp <30.000.
The zoom optical system according to any one of claims 1 to 10, which satisfies the following condition.   The variable magnification optical system according to any one of claims 1 to 11, wherein the second b partial lens group includes a negative meniscus lens having a concave surface directed toward the object side.   The variable power optical system according to claim 1, wherein the second lens group has at least one aspheric surface.   The variable power optical system according to any one of claims 1 to 13, wherein the third lens group has at least one aspherical surface. The front lens group has a positive refractive power;
The rear lens group has negative refractive power;
The variable power optical system according to any one of claims 1 to 14, wherein when the lens position state changes from the wide-angle end state to the telephoto end state, an interval between the front partial lens group and the rear partial lens group increases. system.   The variable magnification optical system according to claim 1, wherein the rear partial lens group has at least one aspheric surface.   The first lens group and the third lens group move in the object direction when the lens position state changes from the wide-angle end state to the telephoto end state, and the movement amount with respect to the image plane is equal. The zoom optical system according to any one of the above.   The variable power optical system according to any one of claims 1 to 17, further comprising an aperture stop in the vicinity of the first lens group or in the first lens group.   19. The variable magnification optical system according to claim 1, wherein when the lens position state changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group decreases. .   At the time of occurrence of camera shake, at least a part of the second lens group is moved so as to have a component in a direction perpendicular to the optical axis, thereby correcting the image position when the camera shake occurs. Item 20. The variable magnification optical system according to any one of Items 1 to 19.   An optical apparatus comprising the variable magnification optical system according to any one of claims 1 to 20. Along the optical axis, from the object side,
Arrange the front lens group and the rear lens group,
As the front lens group, in order from the object side,
Front lens group,
The rear lens group,
As the rear lens group, in order from the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having a positive refractive power, and substantially five lens groups as a whole,
When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the front lens group and the first lens group changes, and the distance between the first lens group and the second lens group is d12w. The distance between the second lens group and the third lens group decreases from d23w to d23t, and the distance between the front lens group and the rear lens group of the front lens group changes. And
The second lens group is in order from the object side.
A 2a partial lens group having negative refractive power;
A 2b partial lens group having negative refractive power,
Either one of the second a partial lens group or the second b partial lens group is configured to be movable so as to have a component in a direction perpendicular to the optical axis,
The 2a partial lens group is composed of a cemented lens in which, in order from the object side, a biconcave lens and a positive meniscus lens having a convex surface facing the object side are cemented,
The combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state is fw123, and the first lens group, the second lens group, and the third lens in the wide-angle end state are set. The combined magnification with the group is βw123, the refractive index of the positive meniscus lens of the 2a partial lens group with respect to the d line is Np, and the refractive index of the 2a partial lens group with respect to the d line of the biconcave lens is Nn . Then, the following formula 0.002 <(d12t−d12w) /BL≦0.064
0.002 <(d23w-d23t) / BL <0.090
-0.150 <Np-Nn <0.045
However, BL = fw123 × (1-βw123)
A zooming method for a zooming optical system that satisfies the above conditions.

Images