JP7564512B2 - Variable magnification optical system, optical device, and method for manufacturing variable magnification optical system - Google Patents

Description

The present invention relates to a variable magnification optical system, an optical device, and a method for manufacturing a variable magnification optical system.

Conventionally, variable power optical systems suitable for photo cameras, electronic still cameras, video cameras, etc. have been proposed (see, for example, Japanese Patent Application Laid-Open No. 2004-198529). However, conventional variable power optical systems have not been able to sufficiently suppress fluctuations in various aberrations during focusing.

JP 2004-198529 A

The first aspect of the present invention is a method for producing a cellular membrane comprising the steps of:
A lens group includes:
When the magnification is changed, the distance between the lens groups changes.
the plurality of lens groups include an object-side focusing lens group that moves during focusing, and at least one image-side focusing lens group that is disposed closer to the image side than the object-side focusing lens group and moves during focusing along a locus different from that of the object-side focusing lens group;
The variable magnification optical system satisfies the following conditional expressions:
MTF1/MTF2 < 5.0
0.2 < BFw/fw < 2.0
however,
MTF1: Absolute value of the amount of movement of the object-side focusing lens group when focusing from an object at infinity to an object at a close distance in the telephoto end state MTF2: Absolute value of the amount of movement of the focusing lens group arranged closest to the object among the image-side focusing lens groups when focusing from an object at infinity to an object at a close distance in the telephoto end state BFw: Back focus of the variable magnification optical system in the wide-angle end state fw: Focal length of the variable magnification optical system in the wide-angle end state

The second aspect of the present invention is
A manufacturing method of a variable magnification optical system having a plurality of lens groups, comprising the steps of:
The distance between the lens groups is changed during magnification change,
the plurality of lens groups are configured to include an object-side focusing lens group that moves during focusing, and at least one image-side focusing lens group that is disposed closer to the image side than the object-side focusing lens group and moves during focusing along a different locus than that of the object-side focusing lens group;
The present invention relates to a manufacturing method for a variable magnification optical system that is configured to satisfy the following conditional expressions:
MTF1/MTF2 < 5.0
0.2 < BFw/fw < 2.0
however,
MTF1: Absolute value of the amount of movement of the object-side focusing lens group when focusing from an object at infinity to an object at a close distance in the telephoto end state MTF2: Absolute value of the amount of movement of the focusing lens group arranged closest to the object among the image-side focusing lens groups when focusing from an object at infinity to an object at a close distance in the telephoto end state BFw: Back focus of the variable magnification optical system in the wide-angle end state fw: Focal length of the variable magnification optical system in the wide-angle end state

FIG. 1 is a cross-sectional view of a variable magnification optical system according to a first embodiment. 2A, 2B, and 2C are diagrams showing various aberrations when the variable magnification optical system according to Example 1 is focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 3A, 3B, and 3C are diagrams showing various aberrations of the variable magnification optical system according to Example 1 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 4 is a cross-sectional view of a variable magnification optical system according to the second embodiment. 5A, 5B, and 5C are diagrams showing various aberrations when the variable magnification optical system according to Example 2 is focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 6A, 6B, and 6C are diagrams showing various aberrations of the variable magnification optical system according to Example 2 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 7 is a cross-sectional view of a variable magnification optical system according to the third embodiment. 8A, 8B, and 8C are diagrams showing various aberrations of the variable magnification optical system according to Example 3 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 9A, 9B, and 9C are diagrams showing various aberrations of the variable magnification optical system according to Example 3 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 10 is a cross-sectional view of a variable magnification optical system according to the fourth embodiment. 11A, 11B, and 11C are diagrams showing various aberrations of the variable power optical system according to Example 4 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 12A, 12B, and 12C are diagrams showing various aberrations of the variable magnification optical system according to Example 4 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 13 is a cross-sectional view of a variable magnification optical system according to a fifth embodiment. 14A, 14B, and 14C are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 15A, 15B, and 15C are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 16 is a cross-sectional view of a variable magnification optical system according to the sixth example. 17A, 17B, and 17C are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 18A, 18B, and 18C are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 19 is a cross-sectional view of a variable magnification optical system according to the seventh example. 20A, 20B, and 20C are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 21A, 21B, and 21C are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 22 is a cross-sectional view of a variable magnification optical system according to the eighth example. 23A, 23B, and 23C are diagrams showing various aberrations of the variable magnification optical system according to Example 8 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 24A, 24B, and 24C are diagrams showing various aberrations of the variable magnification optical system according to Example 8 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 25 is a cross-sectional view of a variable magnification optical system according to a ninth example. 26A, 26B, and 26C are diagrams showing various aberrations of the variable magnification optical system according to Example 9 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 27A, 27B, and 27C are diagrams showing various aberrations of the variable magnification optical system according to Example 9 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 28 is a cross-sectional view of a variable magnification optical system according to a tenth example. 29A, 29B, and 29C are diagrams showing various aberrations of the variable magnification optical system according to Example 10 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 30A, 30B, and 30C are diagrams showing various aberrations of the variable magnification optical system according to Example 10 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 31 is a cross-sectional view of a variable magnification optical system according to an eleventh example. 32A, 32B, and 32C are diagrams showing various aberrations of the variable magnification optical system according to Example 11 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. 33A, 33B, and 33C are diagrams showing various aberrations of the variable magnification optical system according to Example 11 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. FIG. 34 is a diagram showing the configuration of a camera equipped with a variable magnification optical system. FIG. 35 is a flow diagram showing an outline of a method for manufacturing a variable magnification optical system.

The variable magnification optical system, the optical device, and the method for manufacturing the variable magnification optical system according to the present embodiment will be described below.
The variable magnification optical system of this embodiment has a plurality of lens groups, and the spacing between each of the lens groups changes during magnification. The plurality of lens groups include an object-side focusing lens group that moves during focusing, and at least one image-side focusing lens group that is positioned closer to the image side than the object-side focusing lens group and moves on a different trajectory from that of the object-side focusing lens group during focusing, and is configured to satisfy the following conditional expressions (1) and (2).
(1) MTF1/MTF2 < 5.0
(2) 0.2 < BFw/fw < 2.0
however,
MTF1: Absolute value of the amount of movement of the object-side focusing lens group when focusing from an object at infinity to an object at a close distance in the telephoto end state MTF2: Absolute value of the amount of movement of the focusing lens group arranged closest to the object among the image-side focusing lens groups when focusing from an object at infinity to an object at a close distance in the telephoto end state BFw: Back focus of the variable magnification optical system in the wide-angle end state fw: Focal length of the variable magnification optical system in the wide-angle end state

The variable magnification optical system of this embodiment has a plurality of lens groups, and by changing the intervals between the lens groups when changing magnification from the wide-angle end state to the telephoto end state, it is possible to achieve good aberration correction during magnification. In addition, the variable magnification optical system of this embodiment has a plurality of lens groups, an object-side focusing lens group that moves when focusing from an object at infinity to an object at a close distance, and at least one image-side focusing lens group that is arranged on the image side of the object-side focusing lens group and moves on a different trajectory from the object-side focusing lens group when focusing, so that it is possible to effectively suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.
The lens group refers to a portion having at least one lens separated by an air gap, and the lens component refers to a single lens or a cemented lens.

Conditional expression (1) defines the ratio between the absolute value of the movement amount of the object-side focusing lens group when focusing from an object at infinity to a close object in the telephoto end state and the absolute value of the movement amount of the focusing lens group arranged closest to the object among the image-side focusing lens groups when focusing from an object at infinity to a close object in the telephoto end state. By satisfying this conditional expression (1), the variable magnification optical system of this embodiment can effectively suppress the fluctuation of spherical aberration when focusing from an object at infinity to a close object.

If the corresponding value of conditional expression (1) of the variable magnification optical system of this embodiment exceeds the upper limit, the amount of movement of the object-side focusing lens group becomes too large relative to the focusing lens group arranged closest to the object among the image-side focusing lens groups, making it difficult to correct the variation in spherical aberration when focusing from an object at infinity to an object at a close distance. Note that by setting the upper limit of conditional expression (1) to 4.7, the effect of this embodiment can be made more certain. Also, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit of conditional expression (1) to 4.5 ... accordance with conditional expression (1),
It is preferable to set the upper limit value to 4.0, more preferably 3.5, further preferably 2.8, and even more preferably 2.4.

In order to ensure the effect of this embodiment, conditional expression (1) is set as follows:
2.0 < MTF1/MTF2 < 5.0
By setting the lower limit of condition (1) to 2.0 in this way, the fluctuation of spherical aberration during focusing can be suppressed more effectively.

Conditional expression (2) defines the ratio between the back focus of the variable magnification optical system in the wide-angle end state and the focal length of the variable magnification optical system in the wide-angle end state. By satisfying conditional expression (2), the variable magnification optical system of this embodiment can effectively correct various aberrations including coma in the wide-angle end state.
The back focus is the distance on the optical axis from the lens surface closest to the image side to the image plane.

When the corresponding value of conditional expression (2) of the variable magnification optical system of this embodiment exceeds the upper limit, the back focus at the wide-angle end state becomes large relative to the focal length at the wide-angle end state, making it difficult to correct various aberrations including coma at the wide-angle end state.
By setting the upper limit value of condition (2) to 1.70, the effect of this embodiment can be more reliably achieved.
It is preferable to set the upper limit of condition (2) to 1.20, and more preferably 1.00.
It is more preferable to set it to 0.80.

On the other hand, if the corresponding value of the conditional expression (2) of the variable magnification optical system of this embodiment falls below the lower limit, the back focus in the wide-angle end state becomes small relative to the focal length in the wide-angle end state, making it difficult to correct various aberrations, including coma aberration in the wide-angle end state. In addition, it becomes difficult to arrange the mechanical members of the lens barrel. Note that by setting the lower limit of the conditional expression (2) to 0.30, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of the conditional expression (2) to 0.40. It is also preferable to set the lower limit of the conditional expression (2) to 0.45, further 0.50, further 0.55, and further 0.60.
With the above configuration, it is possible to realize a variable magnification optical system that can effectively suppress aberration fluctuations when changing magnification from the wide-angle end state to the telephoto end state, and fluctuations in various aberrations when focusing from an object at infinity to an object at a close distance.

In the variable magnification optical system of this embodiment, it is desirable that at least one of the object-side focusing lens group and the image-side focusing lens group has at least one lens having negative refractive power and that the following conditional expression (3) is satisfied:
(3) 0.45 < (-fFN)/|fF| < 1.70
however,
fFN: focal length of the lens with the strongest negative refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group; fF: focal length of the lens with the strongest negative refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group;

In the variable magnification optical system of this embodiment, at least one of the object-side focusing lens group and the image-side focusing lens group has at least one lens with negative refractive power, which makes it possible to suppress fluctuations in spherical aberration and chromatic aberration when focusing from an object at infinity to an object at a close distance.
The above conditional expression (3) defines the ratio between the focal length of the lens with the strongest negative refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group, and the focal length of the focusing lens group with the strongest refractive power among the object-side focusing lens group and the image-side focusing lens group. By satisfying this conditional expression (3), the variable magnification optical system of this embodiment can suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.

When the corresponding value of the conditional expression (3) of the variable magnification optical system of this embodiment exceeds the upper limit, the refractive power of the focusing lens group with the strongest refractive power among the object side focusing lens group and the image side focusing lens group becomes too strong, and it becomes difficult to suppress the fluctuation of various aberrations including spherical aberration when focusing from an infinite object to a close object.The effect of this embodiment can be more assured by setting the upper limit of the conditional expression (3) to 1.60.In order to make the effect of this embodiment more assured, it is preferable to set the upper limit of the conditional expression (3) to 1.50.It is also preferable to set the upper limit of the conditional expression (3) to 1.40, further 1.30, and further 1.25.

On the other hand, if the corresponding value of the conditional expression (3) of the variable magnification optical system of this embodiment falls below the lower limit, the refractive power of the lens with the strongest negative refractive power among the lenses in the object side focusing lens group and the image side focusing lens group becomes too strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an infinite object to a close object. By setting the lower limit of the conditional expression (3) to 0.47, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of the conditional expression (3) to 0.50. It is also preferable to set the lower limit of the conditional expression (3) to 0.54, and further to 0.60.

In the variable magnification optical system of this embodiment, it is desirable that the object-side focusing lens group has a positive refractive power, which makes it possible to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a close object.

In the variable magnification optical system of the present embodiment, it is desirable that the focusing lens group arranged closest to the image side among the image-side focusing lens groups has a positive refractive power. With this configuration, it is possible to suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.

In the variable magnification optical system of this embodiment, it is preferable that the object-side focusing lens group is constructed of one or two lens components, which makes it possible to reduce the size and weight of the focusing lens group.

In the variable magnification optical system of this embodiment, it is preferable that the image-side focusing lens group is constructed of one or two lens components, which makes it possible to reduce the size and weight of the focusing lens group.

In addition, the variable magnification optical system of this embodiment preferably has a first lens group that is fixed during focusing, closest to the object side. This configuration makes it possible to prevent the lens barrel from becoming too large.

In addition, in the variable magnification optical system of this embodiment, it is desirable that at least one of the object-side focusing lens group and the image-side focusing lens group has at least one lens having negative refractive power and that the following conditional expression (4) is satisfied:
(4) 0.65 < nP/nN < 1.10
however,
nP: the refractive index of the lens with the strongest positive refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group. nN: the refractive index of the lens with the strongest negative refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group.

In the variable magnification optical system of this embodiment, at least one of the object-side focusing lens group and the image-side focusing lens group has at least one lens with negative refractive power, which makes it possible to suppress fluctuations in spherical aberration and chromatic aberration when focusing from an object at infinity to an object at a close distance.
The above conditional expression (4) defines the ratio between the refractive index of the lens with the strongest positive refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group, and the refractive index of the lens with the strongest negative refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group. By satisfying this conditional expression (4), the variable magnification optical system of this embodiment can suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.

When the corresponding value of the conditional expression (4) of the variable magnification optical system of this embodiment exceeds the upper limit, the positive refractive power of the lens with the strongest positive refractive power among the lenses in the object side focusing lens group and the image side focusing lens group becomes too strong, and it becomes difficult to suppress the fluctuation of various aberrations including spherical aberration when focusing from an infinite object to a close object. Note that the effect of this embodiment can be more assured by setting the upper limit value of the conditional expression (4) to 1.05. In addition, in order to make the effect of this embodiment more assured, it is preferable to set the upper limit value of the conditional expression (4) to 1.03. It is also preferable to set the upper limit value of the conditional expression (4) to 1.00, and further to 0.95.

On the other hand, if the value of the conditional expression (4) of the variable magnification optical system of this embodiment falls below the lower limit, the negative refractive power of the lens with the strongest negative refractive power among the lenses in the object side focusing lens group and the image side focusing lens group becomes too strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.
By setting the lower limit of condition (4) to 0.7, the effect of this embodiment can be ensured. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of condition (4) to 0.70. It is also preferable to set the lower limit of condition (4) to 0.75, more preferably 0.80, and even more preferably 0.83.

Moreover, it is desirable for the variable magnification optical system of this embodiment to satisfy the following conditional expression (5).
(5) 0.40 < |fF1|/|f1| <2.60
however,
fF1: focal length of the object-side focusing lens group f1: focal length of the first lens group

Conditional expression (5) defines the ratio between the focal length of the object-side focusing lens group and the focal length of the first lens group. By satisfying conditional expression (5), the variable magnification optical system of this embodiment can effectively suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance, and can suppress the fluctuation of various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

When the corresponding value of conditional expression (5) of the variable magnification optical system of this embodiment exceeds the upper limit, the refractive power of the first lens group becomes strong, and it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state. Note that by setting the upper limit value of conditional expression (5) to 2.55, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (5) to 2.50.
It is more preferable to set the upper limit of condition (5) to 2.30, and more preferably to 2.10.

On the other hand, if the corresponding value of conditional expression (5) of the variable magnification optical system of this embodiment falls below the lower limit, the refractive power of the object-side focusing lens group becomes strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.
By setting the value to 45, the effect of this embodiment can be ensured.
In order to ensure the effect of this embodiment, it is preferable to set the lower limit of condition (5) to 0.47, more preferably 0.50, further preferably 0.55, and further preferably 0.60.

Moreover, it is desirable for the variable magnification optical system of this embodiment to satisfy the following conditional expression (6).
(6) 0.20 < |fF2|/|f1| < 3.80
however,
fF2: focal length of the focusing lens group arranged closest to the image side among the image-side focusing lens groups f1: focal length of the first lens group

Conditional expression (6) defines the ratio of the focal length of the focusing lens group arranged closest to the image side among the image-side focusing lens groups to the focal length of the first lens group.
By satisfying conditional expression (6), it is possible to effectively suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance, and to suppress fluctuations in various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state.

When the corresponding value of conditional expression (6) of the variable magnification optical system of this embodiment exceeds the upper limit, the refractive power of the first lens group becomes strong, and it becomes difficult to suppress the fluctuation of various aberrations, including spherical aberration, when changing magnification from the wide-angle end state to the telephoto end state. Note that by setting the upper limit value of conditional expression (6) to 3.60, the effect of this embodiment can be made more certain. Also, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (6) to 3.40.
It is more preferable to set the upper limit of condition (6) to 3.00, more preferably 2.50, and even more preferably 1.90.

On the other hand, if the corresponding value of conditional expression (6) of the variable magnification optical system of this embodiment falls below the lower limit, the refractive power of the focusing lens group arranged closest to the image side among the image-side focusing lens groups becomes strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance. Note that by setting the lower limit of conditional expression (6) to 0.25, the effect of this embodiment can be made more certain. Also, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (6) to 0.28. Also, it is preferable to set the lower limit of conditional expression (6) to 0.
It is preferable to set the ratio to 0.50, more preferably 0.70, even more preferably 0.90, and even more preferably 1.20.

In the variable magnification optical system of this embodiment, it is preferable that the object-side focusing lens group consists of, in order from the object side, a lens having a positive refractive power and a lens having a negative refractive power. With this configuration, it is possible to effectively suppress the fluctuation of spherical aberration and chromatic aberration when focusing from an object at infinity to an object at a close distance.

It is also preferable that the variable magnification optical system of the present embodiment has an aperture stop, and that the object-side focusing lens group is disposed on the image side of the aperture stop. With this configuration, the weight of the focusing lens group can be reduced.

Moreover, it is desirable for the variable magnification optical system of this embodiment to satisfy the following conditional expression (7).
(7) 0.10 < |fF1|/ft < 3.00
however,
fF1: focal length of the object-side focusing lens group ft: focal length of the variable magnification optical system in the telephoto end state

Conditional expression (7) defines the ratio between the focal length of the object-side focusing lens group and the focal length of the variable magnification optical system in the telephoto end state. By satisfying conditional expression (7), the variable magnification optical system of this embodiment can effectively suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.

When the corresponding value of conditional expression (7) of the variable magnification optical system of this embodiment exceeds the upper limit, the focal length of the object-side focusing lens group becomes long, the amount of movement of the object-side focusing lens group when focusing from an object at infinity to an object at a close distance becomes too large, and it becomes difficult to correct the fluctuation of various aberrations including spherical aberration when focusing from an object at infinity to an object at a close distance.
By setting the value to 80, the effect of this embodiment can be ensured.
In order to ensure the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (7) to 2.60, more preferably 2.20, further preferably 1.90, and further preferably 1.60.

On the other hand, if the corresponding value of conditional expression (7) of the variable magnification optical system of this embodiment falls below the lower limit, the refractive power of the object-side focusing lens group becomes strong, making it difficult to suppress the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.
By setting the value to 12, the effect of this embodiment can be ensured.
In order to ensure the effect of this embodiment, it is preferable to set the lower limit of condition (7) to 0.15.

Moreover, it is desirable for the variable magnification optical system of this embodiment to satisfy the following conditional expression (8).
(8) 0.10 < |fF2|/ft < 3.00
however,
fF2: focal length of the focusing lens group arranged closest to the image side among the image-side focusing lens groups ft: focal length of the variable magnification optical system in the telephoto end state

Conditional expression (8) defines the ratio between the focal length of the focusing lens group arranged closest to the image side among the image-side focusing lens groups and the focal length of the variable magnification optical system in the telephoto end state. By satisfying conditional expression (8), the variable magnification optical system of this embodiment can effectively suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance.

When the corresponding value of conditional expression (8) of the variable magnification optical system of this embodiment exceeds the upper limit, the focal length of the focusing lens group arranged closest to the image side among the image-side focusing lens groups becomes long, and the amount of movement of the focusing lens group arranged closest to the image side when focusing from an object at infinity to an object at a close distance becomes too large,
It becomes difficult to correct the fluctuation of various aberrations, including spherical aberration, when focusing from an object at infinity to an object at a close distance. By setting the upper limit value of conditional expression (8) to 2.80, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (8) to 2.60.

On the other hand, if the corresponding value of the conditional expression (8) of the variable magnification optical system of this embodiment falls below the lower limit, the refractive power of the focusing lens group arranged closest to the image side among the image side focusing lens groups becomes strong, and it becomes difficult to suppress the fluctuation of various aberrations including spherical aberration when focusing from an infinite object to a close object. Note that the effect of this embodiment can be made more certain by setting the lower limit of the conditional expression (8) to 0.12. In addition, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit of the conditional expression (8) to 0.15.

Moreover, it is desirable for the variable magnification optical system of this embodiment to satisfy the following conditional expression (9).
(9) |βWF1|/|βWF2| < 4.00
however,
βWF1: lateral magnification of the object-side focusing lens group in the wide-angle end state when focusing on an object at infinity βWF2: lateral magnification of the focusing lens group arranged closest to the object among the image-side focusing lens groups in the wide-angle end state when focusing on an object at infinity

Conditional expression (9) defines the ratio between the lateral magnification of the object-side focusing lens group in the wide-angle end state when focusing on an object at infinity and the lateral magnification of the focusing lens group arranged closest to the object among the image-side focusing lens groups in the wide-angle end state when focusing on an object at infinity.
By satisfying conditional expression (9), it is possible to effectively suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the wide-angle end state.

When the corresponding value of conditional expression (9) of the variable magnification optical system of this embodiment exceeds the upper limit, the lateral magnification of the object-side focusing lens group in the wide-angle end state when focusing on an object at infinity becomes larger than the lateral magnification of the focusing lens group arranged closest to the object among the image-side focusing lens groups in the wide-angle end state when focusing on an object at infinity, making it difficult to suppress the fluctuation of various aberrations including spherical aberration when focusing from an object at infinity to a close object in the wide-angle end state.
By setting the upper limit value of conditional expression (9) to 0.50, the effect of this embodiment can be made more certain. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (9) to 3.00. It is also preferable to set the upper limit value of conditional expression (9) to 2.50, further 2.00, further 1.50,
It is further preferable to set it to 1.20.

Moreover, it is desirable for the variable magnification optical system of this embodiment to satisfy the following conditional expression (10).
(10) |βRw|/|βRt| < 4.00
however,
βRw: composite lateral magnification from the object-side focusing lens group to the image plane in the wide-angle end state when focusing on an object at infinity βRt: composite lateral magnification from the object-side focusing lens group to the image plane in the telephoto end state when focusing on an object at infinity

Conditional expression (10) defines the ratio between the composite lateral magnification from the object-side focusing lens group to the image plane in the wide-angle end state when focusing on an object at infinity, and the composite lateral magnification from the object-side focusing lens group to the image plane in the telephoto end state when focusing on an object at infinity. By satisfying conditional expression (10), the variable magnification optical system of this embodiment can effectively suppress fluctuations in various aberrations, including spherical aberration, when focusing from an object at infinity to a close object in the wide-angle end state.

When the corresponding value of conditional expression (10) of the variable magnification optical system of this embodiment exceeds the upper limit, the composite lateral magnification from the object-side focusing lens group to the image plane in the wide-angle end state when focusing on an object at infinity becomes larger than the composite lateral magnification from the object-side focusing lens group to the image plane in the telephoto end state when focusing on an object at infinity, making it difficult to suppress the fluctuation of various aberrations including spherical aberration when focusing from an object at infinity to a close object in the wide-angle end state.
Setting it to 0 can ensure the effects of this embodiment. In order to ensure the effects of this embodiment, it is preferable to set the upper limit value of conditional expression (10) to 3.00. It is also preferable to set the upper limit value of conditional expression (10) to 2.60, more preferably 2.20, and even more preferably 1.90.

Moreover, it is desirable for the variable magnification optical system of this embodiment to satisfy the following conditional expression (11).
(11) 15.0°<ωw<85.0°
however,
ωw: half angle of view of the variable magnification optical system in the wide-angle end state

Conditional expression (11) is a condition that defines the optimum value of the angle of view in the wide-angle end state. By satisfying this conditional expression (11), the variable magnification optical system of this embodiment has a wide angle of view while
It is possible to satisfactorily correct various aberrations such as coma, distortion, and curvature of field.

In order to ensure the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (11) to 80.0°.More preferably, it is preferable to set the upper limit value of conditional expression (11) to 75.0°, more preferably to 70.0°, and even more preferably to 65.0°.
In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (11) to 16.0°. It is also preferable to set the lower limit of conditional expression (11) to 17.0°, more preferably 35.0°, more preferably 37.0°, more preferably 39.0°, more preferably 40.0°, and even more preferably 42.0°.

The optical device of this embodiment has a variable magnification optical system with the above-described configuration, which makes it possible to realize an optical device that can effectively suppress aberration fluctuations when changing magnification from the wide-angle end state to the telephoto end state, and when focusing from an object at infinity to an object at a close distance.

The manufacturing method of a variable magnification optical system of this embodiment is a manufacturing method of a variable magnification optical system having a plurality of lens groups, configured so that the spacing between each of the lens groups changes during magnification, the plurality of lens groups are configured to have an object-side focusing lens group that moves during focusing, and at least one image-side focusing lens group that is positioned closer to the image side than the object-side focusing lens group and moves on a trajectory different from that of the object-side focusing lens group during focusing, and is configured to satisfy the following conditional expressions (1) and (2).
(1) MTF1/MTF2 < 5.0
(2) 0.2 < BFw/fw < 2.0
however,
MTF1: Absolute value of the amount of movement of the object-side focusing lens group when focusing from an object at infinity to an object at a close distance in the telephoto end state MTF2: Absolute value of the amount of movement of the focusing lens group arranged closest to the object among the image-side focusing lens groups when focusing from an object at infinity to an object at a close distance in the telephoto end state BFw: Back focus of the variable magnification optical system in the wide-angle end state fw: Focal length of the variable magnification optical system in the wide-angle end state

This makes it possible to manufacture a variable magnification optical system that can effectively suppress aberration fluctuations when changing magnification from the wide-angle end state to the telephoto end state, and when focusing from an object at infinity to a close object.

Hereinafter, a variable magnification optical system according to a numerical example of this embodiment will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a cross-sectional view of a variable magnification optical system according to a first embodiment.
The arrows in Figs. 7, 10, 13, 16, 19, 22, 25, 28, and 31 indicate:
1 shows the movement locus of each lens group when changing magnification from the wide-angle end state (W) to the telephoto end state (T).
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
The sixth lens group G6 has a positive refractive power, and the seventh lens group G7 has a negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The optical system is made up of a biconcave negative lens L12 and a cemented negative lens L13 having a convex surface facing the object side.
The second lens group G2 is made up of a cemented positive lens consisting of a biconvex positive lens L21 and a negative meniscus lens L22 with its concave surface facing the object side.
The third lens group G3 is made up of a cemented positive lens consisting of a negative meniscus lens L31 with a convex surface facing the object side and a biconvex positive lens L32.

The fourth lens group G4 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L41 and a positive meniscus lens L42 with a convex surface facing the object side, and a positive meniscus lens L43 with a convex surface facing the object side.
The fifth lens group G5 is made up of a cemented positive lens consisting of a biconvex positive lens L51 and a negative meniscus lens L52 with its concave surface facing the object side.
The sixth lens group G6 is composed of a biconvex positive lens L61.
The seventh lens group G7 is composed of a negative meniscus lens L71 with its concave surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
All of the lens groups from the first lens group G1 to the seventh lens group G7 move along the optical axis so that the distance between the first lens group G1 and the seventh lens group G7, the distance between the fifth lens group G5 and the sixth lens group G6, and the distance between the sixth lens group G6 and the seventh lens group G7 change.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fifth lens group G5 toward the object along the optical axis as a focusing lens group, and moving the sixth lens group G6 toward the object along the optical axis on a trajectory different from that of the fifth lens group G5.

Table 1 below lists the values of the specifications of the variable magnification optical system according to this embodiment.
In Table 1, f indicates the focal length, and BF indicates the back focus, that is, the distance on the optical axis from the lens surface closest to the image side to the image plane I.
In [Surface Data], m is the order of the optical surface counted from the object side, r is the radius of curvature, d is the surface spacing (the spacing between the nth surface (n is an integer) and the n+1th surface), nd is the refractive index for the d-line (wavelength 587.6 nm), and νd is the Abbe number for the d-line (wavelength 587.6 nm). Additionally, OP is the object surface, variable is the variable surface spacing, S is the aperture stop, and I is the image surface. Note that the radius of curvature r=∞ indicates a plane. The refractive index of air nd=1.00000 is omitted. Additionally, if the lens surface is aspheric, an * is added to the surface number and the paraxial radius of curvature is shown in the column for radius of curvature r.

[Aspherical surface data] shows the aspherical surface coefficients and conic constants for the aspherical surface shown in [Surface data] when the shape is expressed by the following equation.
x=(h ² /r)/[1+{1-κ(h/r) ² } ^1/2 ]
+A4h ⁴ +A6h ⁶ +A8h ⁸ +A10h ¹⁰
Here, h is the height in the direction perpendicular to the optical axis, x is the sag amount which is the distance along the optical axis direction from the tangent plane of the apex of the aspheric surface at height h to the aspheric surface, κ is the conic constant, and A4, A6, A8, and A10 are
is the aspheric coefficient, and r is the paraxial radius of curvature, which is the radius of curvature of the reference sphere.
For example, "1.234E-05" indicates "1.234 ^× 10 ⁻⁵ ." The second-order aspheric coefficient A2 is 0, and is omitted.

In [Various Data], f is the focal length of the entire lens system, FNO is the F-number, 2ω is the angle of view (unit: "°"), Ymax is the maximum image height, TL is the total length of the variable magnification optical system according to this embodiment, i.e., the distance on the optical axis from the first surface to the image surface I, β is the imaging magnification between the object and the image, and d0 is the object surface OP.
The distance on the optical axis from the lens to the first surface, d0 = 0.000 is infinity, i.e., when focusing on an object at infinity, d0
= 641.690, etc., indicates the close distance, i.e., when focusing on a close-distance object, and dn indicates the variable distance between the nth surface and the n+1th surface. Note that f, β indicates f at infinity, β at close range, W at the wide-angle end state, M at the intermediate focal length state, and T at the telephoto end state.
[Lens Group Data] indicates the starting surface number ST and focal length f of each lens group.
[Values of Conditional Expressions] shows values of the respective conditional expressions of the variable magnification optical system according to this embodiment.

Here, the focal length f, the radius of curvature r, and other lengths listed in Table 1 are generally in units of "mm." However, the optical system is not limited to this because the same optical performance can be obtained even if the optical system is proportionally enlarged or reduced.
The symbols in Table 1 described above will be used in the tables of the respective embodiments described later in the same manner.

(Table 1) First Example [Surface Data]
m r d nd νd
OP ∞
1 270.0000 2.900 1.74389 49.53
* 2 33.2562 13.215
3 -1900.2102 2.100 1.59349 67.00
4 35.8236 7.700 2.00100 29.12
5 79.6938 Variable

6 271.3181 7.400 1.83481 42.73
7 -36.9149 1.500 1.75520 27.57
8 164.0000 Variable

9 39.7511 1.500 1.85000 27.03
10 25.6246 10.800 1.59319 67.90
11 -134.6401 Variable

12(S)∞2.350
13 -65.9523 1.300 1.80100 34.92
14 18.5797 4.700 1.90366 31.27
15 51.6074 0.919
16 45.9293 2.500 1.94595 17.98
17 120.0000 Variable

18 47.5350 7.100 1.48749 70.31
19 -24.2409 1.300 1.69895 30.13
20 -74.7188 Variable

21 113.0000 4.200 1.58913 61.15
*22 -108.0000 Variable

*23 -30.5616 1.500 1.58913 61.15
24 -81.9388 BF
I∞

[Aspheric data]
m: 2
Kappa = 0.0000
A4 = 2.97162E-06
A6 = 1.62510E-09
A8 = 2.42658E-13
A10 = 4.56491E-16
A12 = 8.02650E-19

m: 22
Kappa = 1.0000
A4 = 8.43912E-06
A6 = 6.68890E-10
A8 = 1.69267E-11
A10 = -5.36609E-14

m: 23
Kappa = 1.0000
A4 = 8.13845E-06
A6 = -4.05875E-09
A8 = 1.66491E-11
A10 = -5.84964E-14

[Various data]
Magnification ratio: 2.99
W.M.T.
f 22.7 50.0 67.9
FNO 2.92 2.92 2.92
2ω 91.10 45.68 33.64
Ymax 19.32 21.60 21.60
T.L. 188.45 157.95 163.95
BF 11.75 20.19 25.26

W.M.T. W.M.T.
f,β 22.700 50.000 67.900 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 641.690 1469.10 2002.79
d5 63.985 10.998 3.100 63.985 10.998 3.100
d8 1.000 1.763 1.000 1.000 1.763 1.000
d11 1.900 12.973 26.707 1.900 12.973 26.707
d17 20.431 12.752 12.052 20.013 11.839 10.654
d20 8.701 16.480 16.780 8.112 16.125 16.831
d22 7.699 9.815 6.069 8.705 11.084 7.415

[Lens group data]
Group ST f
1 1 -46.132
2 6 102.733
3 9 64.434
4 12 -89.031
5 18 92.237
6 21 94.399
7 23 -83.639

[Conditional expression corresponding value]
(1) MTF1/MTF2 = 1.038
(2) BFw/fw =0.518
(3) (-fFN)/|fF|= 0.563
(4) nP/nN= 0.876
(5) |fF1|/|f1| =1.999
(6) |fF2|/|f1| =2.046
(7) |fF1|/ft = 1.358
(8) |fF2|/ft = 1.390
(9) |βWF1|/|βWF2| =0.719
(10) |βRw|/|βRt| = 1.616
(11) ωw = 45.55°

2A, 2B, and 2C are diagrams showing various aberrations of the variable magnification optical system according to Example 1 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
3A, 3B, and 3C are diagrams showing various aberrations of the variable magnification optical system according to Example 1 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

In each of the aberration diagrams in Fig. 2 and Fig. 3, FNO indicates the F-number, NA indicates the numerical aperture, and Y indicates the image height. In the spherical aberration diagram, the F-number or numerical aperture value corresponding to the maximum aperture is shown, in the astigmatism diagram and the distortion diagram, the maximum value of the image height is shown, and in the coma aberration diagram, the value of each image height is shown. d indicates the d-line (λ=587.6 nm), and g indicates the g-line (λ=435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image surface, and the dashed line indicates the meridional image surface. In the aberration diagrams of each embodiment shown below, the same symbols as in this embodiment are used.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on close distances.

Second Example
FIG. 4 is a diagram showing the lens configuration of a variable magnification optical system according to the second embodiment.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, an aperture stop S, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having positive refractive power.
and a sixth lens group G6 having negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The optical system is made up of a cemented negative lens L1, a negative meniscus lens L12 having a convex surface facing the object side, and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 consists of, in order from the object side, a cemented positive lens consisting of a biconvex positive lens L21 and a negative meniscus lens L22 with its concave surface facing the object side, and a cemented positive lens consisting of a negative meniscus lens L23 with its convex surface facing the object side and a biconvex positive lens L24.

The third lens group G3 is composed of, in order from the object side, a biconcave negative lens L31, and a cemented positive lens consisting of a biconcave negative lens L32 and a biconvex positive lens L33.
The fourth lens group G4 is made up of a cemented positive lens consisting of a biconvex positive lens L41 and a negative meniscus lens L42 with its concave surface facing the object side.
The fifth lens group G5 is composed of a biconvex positive lens L51.
The sixth lens group G6 is made up of a negative meniscus lens L61 with a concave surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
and the distance between the fifth lens group G5 and the sixth lens group G6 are changed.
All of the lens groups from the lens group G1 to the sixth lens group G6 move along the optical axis.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fourth lens group G4 toward the object along the optical axis as a focusing lens group, and moving the fifth lens group G5 toward the object along the optical axis on a trajectory different from that of the fourth lens group G4.

The following Table 2 lists the values of the parameters of the variable magnification optical system in this embodiment.

(Table 2) Second Example [Surface Data]
m r d nd νd
OP ∞
1 217.2239 2.900 1.74389 49.53
* 2 30.2414 13.112
3 1223.5572 2.100 1.59349 67.00
4 35.8181 6.436 2.00069 25.46
5 72.5839 Variable

6 128.9112 7.447 1.81600 46.59
7 -39.6982 1.500 1.85000 27.03
8 -142.9408 1.000
9 40.8283 1.500 1.80518 25.45
10 25.0719 10.948 1.60300 65.44
11 -92.3055 Variable

12(S)∞2.486
13 -55.5201 1.300 1.90265 35.72
14 121.6217 1.190
15 -124.4061 1.300 1.67270 32.18
16 22.4038 6.400 1.80809 22.74
17 -97.2368 Variable

18 62.1388 6.900 1.48749 70.32
19 -23.2151 1.300 1.78472 25.64
20 -50.9732 Variable

21 186.2633 4.200 1.58913 61.15
*22 -79.5614 Variable

*23 -33.8149 1.500 1.58913 61.15
24 -131.2649 BF
I∞

[Aspheric data]
m:2
Kappa = 0.0000
A4 = 3.46899E-06
A6 = 3.81982E-09
A8 = -6.40834E-12
A10 = 1.09738E-14
A12 = -4.82160E-18

m: 22
Kappa = 1.0000
A4 = 6.88818E-06
A6 = -6.09818E-10
A8 = 8.44660E-12
A10 = -2.63571E-14

m: 23
Kappa = 1.0000
A4 = 8.06346E-06
A6 = -8.60497E-09
A8 = 2.28581E-11
A10 = -5.12367E-14

[Various data]
Magnification ratio: 2.99
W.M.T.
f 22.7 50.0 67.9
FNO 2.92 2.92 2.92
2ω 91.24 45.92 33.78
Ymax 19.34 21.60 21.60
TL 188.49 155.49 159.75
BF 16.19 19.69 24.21

W.M.T. W.M.T.
f,β 22.700 50.000 67.900 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 643.745 1470.35 2002.57
d5 63.857 10.035 2.501 63.857 10.035 2.501
d11 2.202 10.972 22.702 2.202 10.972 22.702
d17 19.524 10.852 10.688 19.122 9.959 9.322
d20 8.007 19.445 19.346 7.507 19.082 19.339
d22 5.193 10.974 6.787 6.095 12.231 8.161

[Lens group data]
Group ST f
1 1 -42.007
2 6 36.073
3 12 -74.292
4 18 96.221
5 21 95.186
6 23 -77.759

[Conditional expression corresponding value]
(1) MTF1/MTF2 =0.995
(2) BFw/fw =0.713
(3) (-fFN)/|fF|= 0.583
(4) nP/nN= 0.833
(5) |fF1|/|f1| =2.291
(6) |fF2|/|f1| =2.266
(7) |fF1|/ft = 1.417
(8) |fF2|/ft = 1.402
(9) |βWF1|/|βWF2| = 0.762
(10) |βRw|/|βRt| = 1.663
(11) ωw = 45.62°

5A, 5B, and 5C are diagrams showing the wide-angle end state of the variable magnification optical system according to the second embodiment,
6A to 6C are diagrams illustrating various aberrations when focusing on an object at infinity in an intermediate focal length state and in a telephoto end state.
6A, 6B, and 6C are diagrams showing the wide-angle end state of the variable magnification optical system according to the second embodiment,
6A to 6C are diagrams illustrating various aberrations when focusing on a close-distance object in an intermediate focal length state and in a telephoto end state.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

(Third Example)
FIG. 7 is a diagram showing the lens configuration of a variable magnification optical system according to the third example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
The sixth lens group G6 has a positive refractive power, and the seventh lens group G7 has a negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The optical system is made up of a cemented negative lens L1, a negative meniscus lens L12 having a convex surface facing the object side, and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 is made up of a cemented positive lens consisting of a biconvex positive lens L21 and a negative meniscus lens L22 with its concave surface facing the object side.
The third lens group G3 is made up of a cemented positive lens consisting of a negative meniscus lens L31 with a convex surface facing the object side and a biconvex positive lens L32.

The fourth lens group G4 is made up of a cemented negative lens consisting of a biconcave negative lens L41 and a positive meniscus lens L42 with a convex surface facing the object side.
The fifth lens group G5 is made up of a cemented positive lens consisting of a biconvex positive lens L51 and a negative meniscus lens L52 with its concave surface facing the object side.
The sixth lens group G6 is composed of a biconvex positive lens L61.
The seventh lens group G7 is composed of a negative meniscus lens L71 with its concave surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
All of the lens groups from the first lens group G1 to the seventh lens group G7 move along the optical axis so that the distance between the first lens group G1 and the seventh lens group G7, the distance between the fifth lens group G5 and the sixth lens group G6, and the distance between the sixth lens group G6 and the seventh lens group G7 change.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fifth lens group G5 toward the object along the optical axis as a focusing lens group, and moving the sixth lens group G6 toward the object along the optical axis on a trajectory different from that of the fifth lens group G5.

The following Table 3 shows the values of the parameters of the variable magnification optical system in this embodiment.

(Table 3) Third Example [Surface Data]
m r d nd νd
OP ∞
1 259.2015 2.900 1.74389 49.53
* 2 30.9799 13.410
3 1201.6909 2.100 1.59349 66.99
4 36.4155 6.936 2.00100 29.14
5 81.5436 Variable

6 124.3745 6.555 1.80400 46.60
7 -55.7538 1.500 1.72825 28.38
8 -633.0468 Variable

9 44.9659 1.500 1.85000 27.03
10 27.3358 10.990 1.59319 67.90
11 -89.5168 Variable

12(S)∞2.562
13 -58.2664 1.300 1.68893 31.16
14 20.8969 4.742 1.80809 22.74
15 201.5296 Variable

16 52.2605 6.900 1.48749 70.31
17 -26.1209 1.300 1.69895 30.13
18 -72.7540 Variable

19 130.0000 4.200 1.58913 61.15
*20 -100.4826 Variable

*21 -44.3630 1.500 1.58913 61.15
22 -412.9422 BF
I∞

[Aspheric data]
m: 2
Kappa = 0.0000
A4 = 3.40299E-06
A6 = 1.78453E-09
A8 = -2.01869E-13
A10 = 1.07948E-15
A12 = 2.74510E-19

m: 20
Kappa = 1.0000
A4 = 8.80591E-06
A6 = -1.07404E-09
A8 = 1.74456E-11
A10 = -2.66494E-14

m: 21
Kappa = 1.0000
A4 = 6.66893E-06
A6 = -5.20154E-09
A8 = 5.00802E-12
A10 = -7.75803E-15

[Various data]
Magnification ratio: 2.99
W.M.T.
f 22.7 50.0 67.9
FNO 2.92 2.92 2.92
2ω 91.30 45.88 33.64
Ymax 19.36 21.60 21.60
TL 188.49 156.49 165.34
BF 14.19 20.41 24.73

W.M.T. W.M.T.
f,β 22.700 50.000 67.900 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 643.522 1473.82 2010.17
d5 64.909 10.197 2.263 64.909 10.197 2.263
d8 1.000 1.000 1.000 1.000 1.000 1.000
d11 2.200 12.573 28.831 2.200 12.573 28.831
d15 22.896 13.304 11.893 22.388 12.281 10.318
d18 8.047 19.430 19.884 7.707 19.294 20.259
d20 6.853 11.181 8.344 7.701 12.340 9.543

[Lens group data]
Group ST f
1 1 -45.334
2 6 112.275
3 9 63.547
4 12 -98.234
5 16 92.914
6 19 96.856
7 21 -84.494

[Conditional expression corresponding value]
(1) MTF1/MTF2 = 1.313
(2) BFw/fw =0.625
(3) (-fFN)/|fF|= 0.635
(4) nP/nN= 0.876
(5) |fF1|/|f1| =2.050
(6) |fF2|/|f1| =2.137
(7) |fF1|/ft = 1.368
(8) |fF2|/ft = 1.426
(9) |βWF1|/|βWF2| = 0.723
(10) |βRw|/|βRt| = 2.084
(11) ωw = 45.65°

8A, 8B, and 8C are diagrams showing the wide-angle end state of the variable magnification optical system according to the third embodiment,
6A to 6C are diagrams illustrating various aberrations when focusing on an object at infinity in an intermediate focal length state and in a telephoto end state.
9A, 9B, and 9C are diagrams showing the wide-angle end state of the variable magnification optical system according to the third embodiment,
6A to 6C are diagrams illustrating various aberrations when focusing on a close-distance object in an intermediate focal length state and in a telephoto end state.

It can be seen from each of the aberration diagrams that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

(Fourth Example)
FIG. 10 is a diagram showing the lens configuration of a variable magnification optical system according to the fourth example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having positive refractive power.
and a sixth lens group G6 having negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The lens 10 comprises a cemented negative lens made of a positive meniscus lens L12 having a convex surface facing the object side and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 includes, in order from the object side, a negative meniscus lens L2
1, a biconcave negative lens L22, a biconvex positive lens L23, and a cemented negative lens consisting of a biconcave negative lens L24 and a biconvex positive lens L25.

The third lens group G3 is composed of, in order from the object side, a biconvex positive lens L31, a negative meniscus lens L32 with a concave surface facing the object side, a biconvex positive lens L33, and a biconcave negative lens L34.
The fourth lens group G4 is made up of a cemented positive lens consisting of a biconvex positive lens L41 and a negative meniscus lens L42 with its concave surface facing the object side.
The fifth lens group G5 is composed of a biconvex positive lens L51.
The sixth lens group G6 is composed of, in order from the object side, a negative biconcave lens L61 and a positive meniscus lens L62 with a convex surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
and the distance between the fifth lens group G5 and the sixth lens group G6 are changed.
All of the lens groups from the lens group G1 to the sixth lens group G6 move along the optical axis.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fourth lens group G4 toward the image side along the optical axis and moving the fifth lens group G5 toward the object side along the optical axis as a focusing lens group.

The values of the parameters of the variable magnification optical system in this embodiment are shown in Table 4 below.

(Table 4) Fourth Example [Surface Data]
m r d nd νd
OP ∞
1 1059.3029 1.000 1.84666 23.80
2 88.2318 6.929 1.90265 35.72
3 403.3118 0.200
4 87.3429 6.677 1.81600 46.59
5 899.1448 Variable

*6 145.1405 1.000 1.81600 46.59
7 21.3498 7.013
8 -93.6905 1.000 1.77250 49.62
9 52.8889 0.200
10 40.8152 5.067 1.80518 25.45
11 -74.9610 1.472
12 -36.2791 1.000 1.80400 46.60
13 404.7262 2.056 2.00069 25.46
14 -319.9567 Variable

15(S) ∞ 0.200
16 88.2548 3.685 1.80400 46.60
17 -54.7142 1.284
18 -30.7175 1.000 1.68893 31.16
19 -74.0526 0.200
20 56.5407 4.903 1.71999 50.27
21 -44.3610 4.918
22 -36.9664 1.000 1.72342 38.03
23 80.5817 Variable

24 573.8232 6.525 1.59349 67.00
25 -22.0116 1.000 1.71736 29.57
26 -42.4849 Variable

27 50.5370 6.205 1.55332 71.68
*28 -153.3313 Variable

*29 -95.1749 3.228 1.59551 39.21
30 84.3183 7.544
31 40.5660 7.785 1.59551 39.21
32 180.7170 BF
I∞

[Aspheric data]
m:6
Kappa = 1.0000
A4 = 1.07708E-06
A6 = -2.41884E-09
A8 = 5.80958E-12
A10 = -5.58700E-15

m: 28
Kappa = 1.0000
A4 = 2.10709E-06
A6 = 4.40633E-09
A8 = -1.52762E-11
A10 = 2.31569E-14

m: 29
Kappa = 1.0000
A4 = -6.15448E-06
A6 = 7.32819E-09
A8 = -2.45254E-11
A10 = 3.72863E-14

[Various data]
Magnification ratio: 2.99
W.M.T.
f 22.7 50.3 67.9
FNO 2.92 2.92 2.92
2ω 91.78 46.78 34.60
Ymax 19.23 21.60 21.60
T.L. 155.45 174.13 187.93
BF 13.25 21.65 20.92

W.M.T. W.M.T.
f,β 22.700 50.288 67.900 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 638.473 1426.83 1927.07
d5 2.000 25.012 34.560 2.000 25.012 34.560
d14 29.544 7.040 2.000 29.544 7.040 2.000
d23 6.941 4.850 4.000 8.321 5.940 5.254
d26 12.867 12.278 14.712 10.219 9.978 12.178
d28 7.757 20.212 28.652 9.025 21.422 29.932

[Lens group data]
Group ST f
1 1 131.146
2 6 -21.329
3 15 56.760
4 24 81.373
5 27 69.446
6 29 -1467.881

[Conditional expression corresponding value]
(1) MTF1/MTF2 =0.980
(2) BFw/fw =0.584
(3) (-fFN)/|fF|= 0.936
(4) nP/nN= 0.928
(5) |fF1|/|f1| =0.620
(6) |fF2|/|f1| =0.530
(7) |fF1|/ft = 1.198
(8) |fF2|/ft = 1.023
(9) |βWF1|/|βWF2| = 0.014
(10) |βRw|/|βRt| = 0.005
(11) ωw = 45.89°

11A, 11B, and 11C are diagrams showing various aberrations of the variable magnification optical system according to Example 4 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
12A, 12B, and 12C are diagrams showing various aberrations of the variable magnification optical system according to Example 4 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

Fifth Example
FIG. 13 is a diagram showing the lens configuration of a variable magnification optical system according to the fifth example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
and a sixth lens group G6 having negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The lens 10 comprises a cemented positive lens L12 having a biconvex shape and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 includes, in order from the object side, a negative meniscus lens L2
1, a negative meniscus lens L22 having a concave surface facing the object side, a positive meniscus lens L23 having a concave surface facing the object side, and a negative meniscus lens L24 having a concave surface facing the object side.

The third lens group G3 is, in order from the object side, a positive meniscus lens L having a convex surface facing the object side.
The optical system is made up of a biconvex positive lens L31, a biconvex positive lens L32, and a cemented positive lens consisting of a biconvex positive lens L33 and a negative meniscus lens L34 with its concave surface facing the object side.
The fourth lens group G4 is composed of, in order from the object side, a biconcave negative lens L41 and a biconvex positive lens L42.
The fifth lens group G5 is composed of a biconvex positive lens L51.
The sixth lens group G6 is composed of, in order from the object side, a negative biconcave lens L61 and a positive meniscus lens L62 with a convex surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
and the distance between the fifth lens group G5 and the sixth lens group G6 are changed.
All of the lens groups from the lens group G1 to the sixth lens group G6 move along the optical axis.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fourth lens group G4 toward the object along the optical axis as a focusing lens group, and moving the fifth lens group G5 toward the object along the optical axis on a trajectory different from that of the fourth lens group G4.

The values of the parameters of the variable magnification optical system in this embodiment are shown in Table 5 below.

(Table 5) Fifth Example [Surface Data]
m r d nd νd
OP ∞
1 3049.4158 2.000 1.84666 23.80
2 109.9340 7.861 1.81600 46.59
3 -1409.8119 0.200
4 101.3915 6.059 1.81600 46.59
5 503.4410 Variable

*6 239.3378 1.300 1.81600 46.59
7 22.0458 9.224
8 -40.1436 1.300 1.77250 49.62
9 -121.4951 0.200
10 -196.1454 4.421 1.95000 29.37
11 -34.6549 1.015
12 -29.7495 1.300 1.59349 67.00
13 -185.4662 Variable

14(S) ∞ 0.200
15 47.0680 3.025 1.88300 40.66
16 271.9137 10.130
17 176.7677 2.592 1.59319 67.90
18 -179.0400 0.200
19 86.4232 5.895 1.59319 67.90
20 -27.4209 1.000 1.95000 29.37
21 -41.6214 Variable

22 -33.9616 1.000 1.72825 28.38
23 151.3178 0.200
24 84.0645 3.506 1.71999 50.27
25 -174.4171 Variable

26 140.7071 4.753 1.54814 45.78
*27 -72.5378 Variable

*28 -60.3860 1.300 1.74950 35.25
29 326.8097 1.986
30 45.0000 7.770 1.64000 60.19
31 459.8861 BF
I∞

[Aspheric data]
m:6
Kappa = 1.0000
A4 = 8.90328E-07
A6 = -2.96841E-09
A8 = 5.16084E-12
A10 = -3.05458E-15

m: 27
Kappa = 1.0000
A4 = 2.61448E-06
A6 = 8.65353E-09
A8 = -3.00982E-11
A10 = 4.50822E-14

m: 28
Kappa = 1.0000
A4 = -6.11667E-06
A6 = 9.18242E-09
A8 = -3.76607E-11
A10 = 4.75789E-14

[Various data]
Magnification ratio: 2.99
W.M.T.
f 22.7 49.7 67.9
FNO 2.92 2.92 2.92
2ω 91.48 45.84 32.90
Ymax 19.18 21.60 21.60
T.L. 157.45 170.49 182.85
BF 14.08 21.92 17.11

W.M.T. W.M.T.
f,β 22.701 49.700 67.907 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 640.708 1420.26 1939.82
d5 2.000 24.596 37.406 2.000 24.596 37.406
d13 35.154 8.040 2.000 35.154 8.040 2.000
d21 4.461 8.442 11.773 4.175 8.108 11.453
d25 20.335 18.256 18.682 18.556 15.932 15.718
d27 2.986 10.795 17.440 5.050 13.453 20.723

[Lens group data]
Group ST f
1 1 141.872
2 6 -24.424
3 14 30.546
4 22 -75.468
5 26 88.014
6 28 -713.321

[Conditional expression corresponding value]
(1) MTF1/MTF2 =0.098
(2) BFw/fw =0.620
(3) (-fFN)/|fF|= 0.504
(4) nP/nN= 0.995
(5) |fF1|/|f1| =0.532
(6) |fF2|/|f1| =0.620
(7) |fF1|/ft = 1.111
(8) |fF2|/ft = 1.296
(9) |βWF1|/|βWF2| = 2.449
(10) |βRw|/|βRt| = 1.034
(11) ωw = 45.74°

14A, 14B, and 14C are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
15A, 15B, and 15C are diagrams showing various aberrations of the variable magnification optical system according to Example 5 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

(Sixth Example)
FIG. 16 is a diagram showing the lens configuration of a variable magnification optical system according to the sixth example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.
The sixth lens group G6 has a positive refractive power, and the seventh lens group G7 has a negative refractive power.

The first lens group G1 includes, in order from the object side, a biconvex positive lens L11, and a cemented positive lens consisting of a negative meniscus lens L12 with a convex surface facing the object side and a biconvex positive lens L13.
The second lens group G2 consists of, in order from the object side, a biconcave negative lens L21, a positive meniscus lens L22 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L23 and a positive meniscus lens L24 with a convex surface facing the object side.
The third lens group G3 is composed of, in order from the object side, a biconvex positive lens L31, and a cemented positive lens consisting of a biconvex positive lens L32 and a biconcave negative lens L33.

The fourth lens group G4 is made up of a cemented positive lens consisting of a biconvex positive lens L41 and a negative meniscus lens L42 with its concave surface facing the object side.
The fifth lens group G5 is composed of a negative meniscus lens L51 having a convex surface facing the object side.
The sixth lens group G6 is made up of a positive meniscus lens L61 with its concave surface facing the object side.
The seventh lens group G7 includes, in order from the object side, a negative meniscus lens L7
1 and a biconvex positive lens L72.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
All of the lens groups from the first lens group G1 to the seventh lens group G7 move along the optical axis so that the distance between the first lens group G1 and the seventh lens group G7, the distance between the fifth lens group G5 and the sixth lens group G6, and the distance between the sixth lens group G6 and the seventh lens group G7 change.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fourth lens group G4 toward the object along the optical axis as a focusing lens group, and moving the sixth lens group G6 toward the object along the optical axis on a trajectory different from that of the fourth lens group G4.

The values of the parameters of the variable magnification optical system in this embodiment are shown in Table 6 below.

(Table 6) Sixth Example [Surface Data]
m r d nd νd
OP ∞
1 829.7998 3.542 1.48749 70.32
2 -352.7135 0.200
3 102.3920 1.700 1.67270 32.18
4 65.2892 8.627 1.49700 81.73
5 -4480.3970 Variable

6 -331.7733 1.000 1.77250 49.62
7 47.4606 2.120
8 45.4437 2.785 1.80518 25.45
9 90.1171 3.854
10 -70.4901 1.000 1.67003 47.14
11 34.7167 3.536 1.75520 27.57
12 116.6754 Variable

13 100.8918 3.650 1.80610 40.97
14 -72.8434 0.200
15 48.3355 4.843 1.49700 81.73
16 -53.3052 1.443 1.85026 32.35
17 226.4472 1.323
18(S) ∞ variable

19 56.3197 4.471 1.51680 63.88
20 -38.8956 1.000 1.80100 34.92
21 -92.0195 Variable

22 513.7755 3.255 1.85026 32.35
23 39.1334 Variable

24 -52.5225 4.182 1.71736 29.57
25 -30.1949 Variable

26 -25.8031 1.873 1.81600 46.59
27 -90.1071 0.200
28 139.7088 3.802 1.79504 28.69
29 -94.4559 BF
I∞

[Various data]
Magnification ratio: 4.05
W.M.T.
f 72.1 100.0 292.0
FNO 4.74 4.81 5.88
2ω 34.32 24.20 8.28
Ymax 21.60 21.60 21.60
T.L. 193.32 211.66 248.32
BF 38.32 39.78 62.52

W.M.T. W.M.T.
f,β 72.100 99.963 292.002 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 2117.00 2908.95 8607.60
d5 2.000 28.621 75.058 2.000 28.621 75.058
d12 43.058 34.009 2.000 43.058 34.009 2.000
d18 21.601 19.944 21.366 21.096 19.010 19.414
d21 2.000 3.657 2.235 2.505 4.591 4.188
d23 11.246 10.437 10.009 10.564 10.137 9.509
d25 16.489 16.614 16.522 17.171 16.914 17.022

[Lens group data]
Group ST f
1 1 167.538
2 6 -41.098
3 13 50.455
4 19 95.000
5 22 -49.977
6 24 91.830
7 26 -136.049

[Conditional expression corresponding value]
(1) MTF1/MTF2 =3.903
(2) BFw/fw =0.531
(3) (-fFN)/|fF|= 0.924
(4) nP/nN= 0.842
(5) |fF1|/|f1| = 0.567
(6) |fF2|/|f1| = 0.548
(7) |fF1|/ft = 0.325
(8) |fF2|/ft = 0.314
(9) |βWF1|/|βWF2| = 1.096
(10) |βRw|/|βRt| = 0.934
(11) ωw = 17.16°

17A, 17B, and 17C are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
18A, 18B, and 18C are diagrams showing various aberrations of the variable magnification optical system according to Example 6 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

Seventh Example
FIG. 19 is a diagram showing the lens configuration of a variable magnification optical system according to the seventh example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having positive refractive power.
The sixth lens group G6 has a negative refractive power, and the seventh lens group G7 has a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The lens 10 comprises a cemented positive lens L12 having a biconvex shape and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 includes, in order from the object side, a biconcave negative lens L21, a biconcave negative lens L22, and a cemented positive lens consisting of a biconvex positive lens L23 and a biconcave negative lens L24.

The third lens group G3 is composed of, in order from the object side, a biconvex positive lens L31, and a cemented positive lens consisting of a biconvex positive lens L32 and a biconcave negative lens L33.
The fourth lens group G4 is composed of, in order from the object side, a biconvex positive lens L41 and a negative meniscus lens L42 with a concave surface facing the object side.
The fifth lens group G5 is composed of a biconvex positive lens L51.
The sixth lens group G6 is made up of a cemented negative lens consisting of a positive meniscus lens L61 with its concave surface facing the object side and a biconcave negative lens L62.
The seventh lens group G7 is composed of a positive meniscus lens L71 with its concave surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
All of the lens groups from the first lens group G1 to the seventh lens group G7 move along the optical axis so that the distance between the first lens group G1 and the seventh lens group G7, the distance between the fifth lens group G5 and the sixth lens group G6, and the distance between the sixth lens group G6 and the seventh lens group G7 change.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fourth lens group G4 toward the image side along the optical axis and moving the fifth lens group G5 toward the object side along the optical axis as a focusing lens group.

The following Table 7 lists the values of the parameters of the variable magnification optical system in this embodiment.

(Table 7) Seventh Example [Surface Data]
m r d nd νd
OP ∞
1 137.2611 2.000 1.85000 27.03
2 66.9538 6.897 1.59319 67.90
3 -677.5498 0.200
4 107.1491 4.136 1.61800 63.34
5 9353.1970 Variable

*6 -150.8738 2.000 1.90265 35.72
7 25.5606 4.779
8 -260.6181 1.000 1.81600 46.59
9 86.2883 0.200
10 41.4737 5.687 1.84666 23.78
11 -48.7116 1.000 1.81600 46.59
12 54.7043 Variable

13(S) ∞ 0.200
14 44.1680 2.899 1.77250 49.62
15 -280.6415 0.200
16 27.1646 4.022 1.59319 67.90
17 -146.4206 1.000 1.95000 29.37
18 51.2305 Variable

19 50.9241 2.999 1.83481 42.73
20 -182.3279 2.176
21 -80.2256 1.000 1.88300 40.66
22 -715.7217 Variable

23 101.2327 2.235 1.83481 42.73
*24 -257.5032 Variable

*25 -283.1336 4.085 1.58144 40.98
26 -18.4049 1.000 1.90366 31.27
27 87.0702 Variable

28 -136.5964 6.525 1.59319 67.90
29 -38.7359
I∞

[Aspheric data]
m:6
Kappa = 1.0000
A4 = 1.67289E-07
A6 = -1.03260E-09
A8 = 5.37315E-12
A10 = -4.58982E-15

m: 24
Kappa = 1.0000
A4 = 4.43454E-06
A6 = 2.09008E-08
A8 = -1.49527E-10
A10 = 8.49155E-13

m: 25
Kappa = 1.0000
A4 = -2.21915E-05
A6 = 1.15956E-07
A8 = -1.94063E-09
A10 = 9.93961E-12

[Various data]
Magnification ratio: 8.50
W.M.T.
f 24.7 70.0 210.0
FNO 3.47 5.31 6.52
2ω 85.94 32.52 11.08
Ymax 19.90 21.60 21.60
T.L. 141.66 173.63 194.45
BF 23.35 32.36 13.26

W.M.T. W.M.T.
f,β 24.700 70.005 209.991 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 706.534 2031.32 6175.90
d5 2.002 22.984 54.077 2.002 22.984 54.077
d12 37.630 16.703 2.000 37.630 16.703 2.000
d18 9.388 7.991 4.000 9.688 8.290 4.039
d22 7.722 6.619 11.160 6.491 5.369 9.139
d24 2.215 7.801 20.136 3.147 8.752 21.938
d27 3.110 22.940 33.576 3.110 22.940 33.576

[Lens group data]
Group ST f
1 1 113.050
2 6 -19.624
3 13 42.460
4 19 84.928
5 23 87.292
6 25 -33.119
7 28 88.941

[Conditional expression corresponding value]
(1) MTF1/MTF2 =0.022
(2) BFw/fw = 0.945
(3) (-fFN)/|fF|= 1.206
(4) nP/nN= 0.974
(5) |fF1|/|f1| = 0.751
(6) |fF2|/|f1| = 0.772
(7) |fF1|/ft = 0.404
(8) |fF2|/ft = 0.416
(9) |βWF1|/|βWF2| = 0.616
(10) |βRw|/|βRt| = 1.858
(11) ωw = 42.97°

20A, 20B, and 20C are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
21A, 21B, and 21C are diagrams showing various aberrations of the variable magnification optical system according to Example 7 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

Eighth Example
FIG. 22 is a diagram showing the lens configuration of a variable magnification optical system according to the eighth example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, an aperture stop S, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.
The sixth lens group G6 has a positive refractive power, and the seventh lens group G7 has a negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The optical system is made up of a cemented positive lens consisting of a negative meniscus lens L12 having a convex surface facing the object side and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 consists of, in order from the object side, a cemented positive lens consisting of a biconvex positive lens L21 and a negative meniscus lens L22 with its concave surface facing the object side, and a cemented positive lens consisting of a negative meniscus lens L23 with its convex surface facing the object side and a biconvex positive lens L24.

The third lens group G3 includes, in order from the object side, a negative meniscus lens L3 having a concave surface facing the object side.
1, and a cemented positive lens consisting of a biconcave negative lens L32 and a positive meniscus lens L33 with a convex surface facing the object side.
The fourth lens group G4 is composed of a biconvex positive lens L41.
The fifth lens group G5 is composed of a negative meniscus lens L51 with a concave surface facing the object side.
The sixth lens group G6 is composed of a biconvex positive lens L61.
The seventh lens group G7 is composed of a negative meniscus lens L71 with its concave surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
All of the lens groups from the first lens group G1 to the seventh lens group G7 move along the optical axis so that the distance between the first lens group G1 and the seventh lens group G7, the distance between the fifth lens group G5 and the sixth lens group G6, and the distance between the sixth lens group G6 and the seventh lens group G7 change.

In the optical system according to this embodiment, the fourth lens group G4 is moved toward the object side along the optical axis as the focusing lens group, and the fifth lens group G5 and the sixth lens group G6 are moved toward the object side along the optical axis as the focusing lens group.
By moving the lens group G4 along the optical axis toward the object side on a different trajectory from that of the lens group G5, focusing from an object at infinity to an object at a close distance is performed.

The following Table 8 lists the values of the parameters of the variable magnification optical system in this embodiment.

(Table 8) Eighth Example [Surface Data]
m r d nd νd
OP ∞
1 250.0000 2.900 1.74389 49.53
* 2 28.0269 12.424
3 154.1167 2.100 1.59349 67.00
4 32.5416 6.969 2.00069 25.46
5 61.8764 Variable

6 175.0869 5.997 1.81600 46.59
7 -52.8034 1.500 1.85000 27.03
8 -204.9882 1.000
9 45.2860 1.500 1.80518 25.45
10 26.6188 11.527 1.60300 65.44
11 -76.6492 Variable

12(S)∞2.465
13 -64.5009 1.300 1.90265 35.72
14 -217.6883 0.200
15 -214.1041 1.300 1.67270 32.18
16 26.6878 6.400 1.80809 22.74
17 502.6822 Variable

18 65.6282 5.000 1.48749 70.32
19 -65.3105 Variable

20 -52.0851 1.300 1.84666 23.80
21 -201.9547 Variable

22 185.0000 5.300 1.58913 61.15
*23 -50.5905 Variable

*24 -27.3977 1.500 1.58913 61.15
25 -49.4756 BF
I∞

[Aspheric data]
m:2
Kappa = 0.0000
A4 = 3.95960E-06
A6 = 3.76748E-09
A8 = -5.23494E-12
A10 = 1.04782E-14
A12 = -4.82160E-18

m: 23
Kappa = 1.0000
A4 = 6.76320E-06
A6 = -8.33082E-09
A8 = 3.88079E-11
A10 = -7.09278E-14

m: 24
Kappa = 1.0000
A4 = 5.00393E-06
A6 = -8.92918E-09
A8 = 2.86537E-11
A10 = -5.32582E-14

[Various data]
Magnification ratio: 2.99
W.M.T.
f 22.7 50.0 67.9
FNO 3.03 3.00 3.03
2ω 91.04 45.96 33.62
Ymax 19.30 21.60 21.60
TL 188.49 155.49 167.35
BF 16.20 23.37 32.67

W.M.T. W.M.T.
f,β 22.700 49.999 67.899 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 644.489 1474.05 2002.27
d5 64.883 10.266 5.946 64.883 10.266 5.946
d11 2.200 12.775 27.038 2.200 12.775 27.038
d17 20.035 8.462 6.571 19.026 7.439 4.593
d19 2.030 3.706 4.816 1.360 3.164 4.349
d21 4.601 9.046 14.467 4.908 8.936 15.092
d23 7.862 17.178 5.159 9.234 18.853 6.979

[Lens group data]
Group ST f
1 1 -42.744
2 6 40.599
3 12 -105.371
4 18 68.000
5 20 -83.229
6 22 68.000
7 24 -106.909

[Conditional expression corresponding value]
(1) MTF1/MTF2 =0.809
(2) BFw/fw =0.713
(3) (-fFN)/|fF|= 1.224
(4) nP/nN= 0.806
(5) |fF1|/|f1| =1.591
(6) |fF2|/|f1| =1.591
(7) |fF1|/ft = 1.001
(8) |fF2|/ft = 1.001
(9) |βWF1|/|βWF2| = 0.350
(10) |βRw|/|βRt| = 1.387
(11) ωw = 45.52°

23A, 23B, and 23C are diagrams showing various aberrations of the variable magnification optical system according to Example 8 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
24A, 24B, and 24C are diagrams showing various aberrations of the variable magnification optical system according to Example 8 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

It can be seen from each of the aberration diagrams that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

Ninth Example
FIG. 25 is a diagram showing the lens configuration of a variable magnification optical system according to the ninth example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
The sixth lens group G6 has a positive refractive power, and the seventh lens group G7 has a negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The lens 10 comprises a cemented negative lens L12 made of a biconvex positive lens L12 and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 consists of, in order from the object side, a biconcave negative lens L21, a negative meniscus lens L22 with its concave surface facing the object side, a cemented negative lens consisting of a positive meniscus lens L23 with its concave surface facing the object side, and a negative meniscus lens L24 with its concave surface facing the object side.

The third lens group G3 includes, in order from the object side, a positive meniscus lens L3 having a convex surface facing the object side.
The optical system is made up of a cemented positive lens L31, a negative meniscus lens L32 having a convex surface facing the object side and a positive meniscus lens L33 having a convex surface facing the object side, and a biconvex positive lens L34.
The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L4
1 and a biconcave negative lens L42.
The fifth lens group G5 is made up of a cemented positive lens consisting of a biconvex positive lens L51 and a negative meniscus lens L52 with its concave surface facing the object side.
The sixth lens group G6 is made up of a positive meniscus lens L61 with its concave surface facing the object side.
The seventh lens group G7 is composed of a biconcave negative lens L71.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
All of the lens groups from the first lens group G1 to the seventh lens group G7 move along the optical axis so that the distance between the first lens group G1 and the seventh lens group G7, the distance between the fifth lens group G5 and the sixth lens group G6, and the distance between the sixth lens group G6 and the seventh lens group G7 change.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fifth lens group G5 toward the object along the optical axis as a focusing lens group, and moving the sixth lens group G6 toward the object along the optical axis on a trajectory different from that of the fifth lens group G5.

Table 9 below lists the values of the parameters of the variable magnification optical system in this embodiment.

(Table 9) Ninth Example [Surface Data]
m r d nd νd
OP ∞
1 3442.9453 2.000 2.00100 29.12
2 67.9723 9.758 1.59319 67.90
3 -152.3923 0.200
4 58.4962 5.618 1.81600 46.59
5 401.1678 Variable

*6 -290.9507 1.400 1.88300 40.66
7 23.9500 5.968
8 -85.0139 1.200 1.83481 42.73
9 -120.7468 5.617 1.84666 23.80
10 -22.1853 1.200 1.81600 46.59
11 -285.7763 Variable

12(S) ∞ 0.200
13 43.7782 3.108 1.69680 55.52
14 471.1855 0.200
15 32.7556 1.000 1.83481 42.73
16 21.7787 4.328 1.59319 67.90
17 90.7958 0.200
18 34.8267 4.022 1.58144 40.98
19 -155.1147 Variable

*20 -30.2170 1.817 1.90200 25.26
21 -25.8045 0.200
22 -168.2619 1.000 1.90366 31.27
23 32.2596 Variable

24 38.3747 4.859 1.49700 81.73
25 -32.4370 1.000 2.00069 25.46
26 -70.7616 Variable

27 -63.4136 3.063 1.56732 42.58
*28 -25.4716 Variable

*29 -40.3736 1.500 1.81600 46.59
30 223.1585 BF
I∞

[Aspheric data]
m:6
Kappa = 1.0000
A4 = 1.12990E-06
A6 = -1.48448E-09
A8 = 2.59485E-12
A10 = -2.03608E-15

m: 20
Kappa = 1.0000
A4 = -1.25538E-05
A6 = 2.12431E-08
A8 = -1.35330E-10
A10 = 4.53472E-13

m: 28
Kappa = 1.0000
A4 = 2.57266E-05
A6 = 5.03605E-08
A8 = -2.10329E-10
A10 = 3.98690E-13

m: 29
Kappa = 1.0000
A4 = 1.23110E-05
A6 = 2.00664E-08
A8 = -1.99371E-10
A10 = 2.96093E-13

[Various data]
Magnification ratio: 8.97
W.M.T.
f 24.8 70.0 222.0
FNO 3.69 5.39 6.42
2ω 85.32 33.28 10.80
Ymax 20.30 21.60 21.60
TL 152.38 168.67 204.50
BF 13.25 40.90 75.50

W.M.T. W.M.T.
f,β 24.750 70.000 222.000 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 708.545 2047.97 6602.17
d5 2.000 19.489 42.969 2.000 19.489 42.969
d11 40.184 17.902 2.000 40.184 17.902 2.000
d19 2.003 3.971 9.577 2.003 3.971 9.577
d23 10.844 6.751 7.946 10.369 6.000 6.221
d26 15.034 12.261 4.050 14.947 12.499 5.206
d28 9.603 7.938 3.000 10.165 8.452 3.568

[Lens group data]
Group ST f
1 1 93.169
2 6 -21.680
3 12 24.825
4 20 -35.481
5 24 85.936
6 27 72.909
7 29 -41.791

[Conditional expression corresponding value]
(1) MTF1/MTF2 =3.034
(2) BFw/fw =0.536
(3) (-fFN)/|fF|= 0.832
(4) nP/nN= 0.786
(5) |fF1|/|f1| = 0.922
(6) |fF2|/|f1| = 0.783
(7) |fF1|/ft = 0.387
(8) |fF2|/ft = 0.328
(9) |βWF1|/|βWF2| = 0.607
(10) |βRw|/|βRt| = 0.815
(11) ωw = 42.66°

26A, 26B, and 26C are diagrams showing various aberrations of the variable magnification optical system according to Example 9 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
27A, 27B, and 27C are diagrams showing various aberrations of the variable magnification optical system according to Example 9 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

(Tenth Example)
FIG. 28 is a diagram showing the lens configuration of a variable magnification optical system according to a tenth example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power.
and a sixth lens group G6 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a biconvex positive lens L11, and a cemented positive lens consisting of a negative meniscus lens L12 with a convex surface facing the object side and a biconvex positive lens L13.
The second lens group G2 includes, in order from the object side, a negative meniscus lens L2
1, a positive meniscus lens L22 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L23 and a positive meniscus lens L24 with a convex surface facing the object side.
The third lens group G3 is composed of, in order from the object side, a biconvex positive lens L31, and a cemented positive lens consisting of a biconvex positive lens L32 and a biconcave negative lens L33.

The fourth lens group G4 is composed of a negative meniscus lens L41 with a convex surface facing the object side, and a cemented positive lens L42 having a biconvex shape.
The fifth lens group G5 is composed of, in order from the object side, a biconvex positive lens L51 and a biconcave negative lens L52.
The sixth lens group G6 includes, in order from the object side, a negative meniscus lens L6
1 and a biconvex positive lens L62.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
and the distance between the fifth lens group G5 and the sixth lens group G6 are changed.
All of the lens groups from the lens group G1 to the sixth lens group G6 move along the optical axis.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fourth lens group G4 toward the object side along the optical axis and moving the fifth lens group G5 toward the image side along the optical axis as a focusing lens group.

The following Table 10 shows the values of the various elements of the variable magnification optical system in this embodiment.

(Table 10) 10th Example [Surface Data]
m r d nd νd
OP ∞
1 339.1302 3.342 1.48749 70.32
2 -1748.8042 0.200
3 113.3340 1.700 1.62004 36.40
4 62.3111 8.286 1.49700 81.73
5 -790.8224 Variable

6 452.0591 1.300 1.80400 46.60
7 41.1492 4.042
8 41.3304 3.091 1.68893 31.16
9 98.8092 4.158
10 -68.4923 1.000 1.70000 48.10
11 36.0772 3.318 1.80518 25.45
12 117.8747 Variable

13 180.8711 3.540 1.80400 46.60
14 -64.2101 0.200
15 40.7438 5.229 1.49700 81.73
16 -52.5435 1.200 1.85026 32.35
17 200.0407 1.376
18(S) ∞ variable

19 68.3281 1.200 1.71736 29.57
20 20.1023 6.000 1.56732 42.58
21 -61.5874 Variable

22 188.7697 2.905 1.72825 28.38
23 -56.4394 0.719
24 -72.6983 1.000 1.80400 46.60
25 30.9300 Variable

26 -22.2025 1.300 1.69680 55.52
27 -38.2594 0.200
28 95.0769 3.373 1.80610 40.97
29 -205.8129 BF
I∞

[Various data]
Magnification ratio: 4.05
W.M.T.
f 72.1 100.0 292.0
FNO 4.68 4.86 5.88
2ω 33.86 24.02 8.26
Ymax 21.60 21.60 21.60
T.L. 193.32 209.38 244.81
BF 38.32 41.53 60.32

W.M.T. W.M.T.
f,β 72.100 100.000 292.000 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 2108.51 2898.12 8529.76
d5 2.000 26.301 76.285 2.000 26.301 76.285
d12 45.791 35.345 2.000 45.791 35.345 2.000
d18 29.471 29.387 29.007 28.880 29.181 28.801
d21 2.000 3.362 2.000 2.786 4.328 3.858
d25 16.057 14.780 16.521 15.862 14.019 14.868

[Lens group data]
Group ST f
1 1 171.900
2 6 -43.196
3 13 51.979
4 19 82.476
5 22 -51.000
6 26 48383.794

[Conditional expression corresponding value]
(1) MTF1/MTF2 =0.125
(2) BFw/fw =0.531
(3) (-fFN)/|fF|= 0.527
(4) nP/nN= 0.913
(5) |fF1|/|f1| =0.480
(6) |fF2|/|f1| =0.297
(7) |fF1|/ft = 0.282
(8) |fF2|/ft = 0.175
(9) |βWF1|/|βWF2| = 0.288
(10) |βRw|/|βRt| = 0.911
(11) ωw = 16.93°

29A, 29B, and 29C are diagrams showing various aberrations of the variable magnification optical system according to Example 10 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
30A, 30B, and 30C are diagrams showing various aberrations of the variable magnification optical system according to Example 10 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

(Eleventh embodiment)
FIG. 31 is a diagram showing the lens configuration of a variable magnification optical system according to the eleventh example.
The variable magnification optical system according to this embodiment includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.
The sixth lens group G6 has a positive refractive power, and the seventh lens group G7 has a negative refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1
The optical system is made up of a biconcave negative lens L12 and a cemented positive lens L13 having a convex surface facing the object side.
The second lens group G2 is made up of a cemented positive lens consisting of a biconvex positive lens L21 and a negative meniscus lens L22 with its concave surface facing the object side.
The third lens group G3 is made up of a cemented positive lens consisting of a negative meniscus lens L31 with a convex surface facing the object side and a biconvex positive lens L32.

The fourth lens group G4 is made up of a cemented negative lens consisting of a biconcave negative lens L41 and a positive meniscus lens L42 with a convex surface facing the object side.
The fifth lens group G5 is composed of a biconvex positive lens L51.
The sixth lens group G6 is composed of a biconvex positive lens L61.
The seventh lens group G7 is composed of a negative meniscus lens L71 with its concave surface facing the object side.

In the variable magnification optical system according to this embodiment, when the magnification is changed between the wide-angle end state and the telephoto end state, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5,
All of the lens groups from the first lens group G1 to the seventh lens group G7 move along the optical axis so that the distance between the first lens group G1 and the seventh lens group G7, the distance between the fifth lens group G5 and the sixth lens group G6, and the distance between the sixth lens group G6 and the seventh lens group G7 change.

In the optical system of this embodiment, focusing from an object at infinity to an object at close range is performed by moving the fifth lens group G5 toward the object along the optical axis as a focusing lens group, and moving the sixth lens group G6 toward the object along the optical axis on a trajectory different from that of the fifth lens group G5.

The following Table 11 shows the values of the various elements of the variable magnification optical system in this embodiment.

(Table 11) Eleventh Example [Surface Data]
m r d nd νd
OP ∞
1 260.0000 2.900 1.74389 49.53
* 2 30.1702 13.784
3 -1991.6463 2.100 1.59349 67.00
4 33.7055 8.364 2.00100 29.13
5 89.6077 Variable

6 108.4958 8.489 1.80100 34.92
7 -30.7757 1.500 1.80518 25.45
8 -204.3062 Variable

9 45.1018 1.500 1.85000 27.03
10 24.0000 9.603 1.59319 67.90
11 -88.4112 Variable

12(S)∞1.733
13 -63.2999 1.300 1.65100 56.24
14 36.0420 2.727 1.90265 35.72
15 90.4648 Variable

16 139.2934 5.000 1.48749 70.32
17 -72.7540 Variable

18 554.8019 4.200 1.58913 61.15
*19 -54.8898 Variable

*20 -29.0077 1.500 1.84666 23.80
21 -45.1973 BF
I∞

[Aspheric data]
m: 2
Kappa = 0.0000
A4 = 3.70839E-06
A6 = 7.95920E-10
A8 = 7.22303E-12
A10 = -1.14971E-14
A12 = 9.51080E-18

m: 19
Kappa = 1.0000
A4 = 5.13891E-06
A6 = -3.95654E-09
A8 = 1.36188E-11
A10 = -1.64821E-14

m: 20
Kappa = 1.0000
A4 = 4.54393E-06
A6 = -1.30549E-09
A8 = 6.99274E-13
A10 = 4.71450E-15

[Various data]
Magnification ratio: 2.99
W.M.T.
f 22.7 50.0 67.9
FNO 4.21 5.58 5.88
2ω 92.68 46.22 33.64
Ymax 19.70 21.60 21.60
TL 188.49 156.49 166.42
BF 14.19 21.35 26.73

W.M.T. W.M.T.
f,β 22.700 50.000 67.900 -0.033 -0.033 -0.033
d0 0.000 0.000 0.000 642.626 1479.20 2020.08
d5 62.024 9.333 2.263 62.024 9.333 2.263
d8 1.536 1.576 1.000 1.536 1.576 1.000
d11 2.200 6.706 19.808 2.200 6.706 19.808
d15 25.740 8.889 12.359 25.733 7.830 10.488
d17 3.523 29.546 31.736 2.523 29.489 32.585
d19 14.577 14.391 7.819 15.584 15.506 8.840

[Lens group data]
Group ST f
1 1 -47.325
2 6 90.647
3 9 68.586
4 12 -74.902
5 16 98.800
6 18 85.000
7 20 -99.892

[Conditional expression corresponding value]
(1) MTF1/MTF2 = 1.831
(2) BFw/fw =0.625
(5) |fF1|/|f1| =2.088
(6) |fF2|/|f1| =1.796
(7) |fF1|/ft = 1.455
(8) |fF2|/ft = 1.252
(9) |βWF1|/|βWF2| = 0.764
(10) |βRw|/|βRt| = 2.455
(11) ωw = 46.34°

32A, 32B, and 32C are diagrams showing various aberrations of the variable magnification optical system according to Example 11 when focused on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
33A, 33B, and 33C are diagrams showing various aberrations of the variable magnification optical system according to Example 11 when focusing on a close object in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

From each of the aberration diagrams, it can be seen that the variable magnification optical system of this embodiment has excellent imaging performance by effectively correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing on a close-distance object.

According to each of the above embodiments, it is possible to realize a variable magnification optical system having high optical performance that effectively suppresses aberration fluctuations when changing magnification from the wide-angle end state to the telephoto end state and when focusing from an object at infinity to a close object. Furthermore, according to each of the above embodiments, it is possible to realize a lightweight and compact focusing lens group, so that a driving mechanism for the focusing lens group can be made compact, and a high-speed and highly quiet focusing operation can be realized without increasing the size of the lens barrel.

It should be noted that the above examples are merely examples of the present invention, and the present invention is not limited to these. The following contents can be appropriately adopted within the scope that does not impair the optical performance of the variable magnification optical system of this embodiment.

As numerical examples of the variable magnification optical system of this embodiment, six-group configurations and seven-group configurations have been shown, but
The present embodiment is not limited to this, and a variable magnification optical system with other group configurations (e.g., eight groups, etc.) may be configured. Specifically, a lens or lens group may be added to the most object side or the most image side of the variable magnification optical system of each of the above examples. Alternatively, a lens or lens group may be added between adjacent lens groups.

In the above embodiments, two or three lens groups are used as the focusing lens group, but some of the lens groups or four or more lens groups may be used as the focusing lens group. Each focusing lens group may be composed of one or two lens components, and a configuration composed of one lens component is more preferable. Such focusing lens groups can be applied to autofocusing, and are also suitable for driving by an autofocus motor, such as an ultrasonic motor, a stepping motor, or a VCM motor.

In the variable magnification optical system of each of the above embodiments, any of the lens groups may be entirely or partially
The vibration isolation group may be configured to perform vibration isolation by moving the group so as to include a component in a direction perpendicular to the optical axis, or by rotating (swinging) the group in a plane including the optical axis.

In addition, the lens surface of the lens constituting the variable magnification optical system of each of the above embodiments may be spherical or flat, or may be aspheric. When the lens surface is spherical or flat, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented, which is preferable. In addition, even if the image plane is shifted, deterioration of depiction performance is small, which is preferable. When the lens surface is aspheric, it may be an aspheric surface formed by grinding, a glass molded aspheric surface formed by molding glass into an aspheric shape using a mold, or a composite aspheric surface formed by forming a resin provided on a glass surface into an aspheric shape. In addition, the lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In addition, in the variable magnification optical systems of each of the above embodiments, it is preferable that the aperture diaphragm S is located between the second lens group G2 and the third lens group G3, or between the third lens group G3 and the fourth lens group G4, but it is also possible to use a configuration in which no component is provided as an aperture diaphragm and the lens frame serves that role instead.

In addition, the lens surfaces of the lenses constituting the variable magnification optical system of each of the above embodiments may be coated with an anti-reflection coating having a high transmittance over a wide wavelength range, thereby reducing flare and ghosting and achieving high optical performance with high contrast.

Next, a camera equipped with the variable magnification optical system of this embodiment will be described with reference to FIG.
FIG. 34 is a diagram showing the configuration of a camera equipped with the variable magnification optical system of this embodiment.
As shown in FIG. 34, the camera 1 is a so-called mirrorless camera of an interchangeable lens type equipped with the variable magnification optical system according to the first embodiment as the photographic lens 2.

In this camera 1, light from an object (subject) (not shown) is collected by a photographing lens 2 and passes through an OLPF (Optical low pass filter) (not shown) to form a subject image on an imaging surface of an imaging unit 3. The subject image is then photoelectrically converted by a photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. This allows the photographer to observe the subject through the EVF 4.
Furthermore, when the photographer presses a release button (not shown), the image of the subject generated by the imaging unit 3 is stored in a memory (not shown). In this manner, the photographer can photograph the subject using the camera 1.

Here, the variable magnification optical system according to the first embodiment mounted as the photographing lens 2 in the camera 1 has good optical performance as described above, and the focusing lens group is made lighter and smaller. That is, the camera 1 realizes high optical performance that satisfactorily suppresses aberration fluctuations when changing magnification from the wide-angle end state to the telephoto end state and when focusing from an infinitely distant object to a close-distance object, and can achieve high-speed focusing operation by making the focusing lens group smaller and lighter. Note that even if a camera is constructed that is mounted as the photographing lens 2 with the variable magnification optical system according to the second to eleventh embodiments, it can achieve the same effect as the camera 1. Also, even if the variable magnification optical system according to each of the above embodiments is mounted on a single-lens reflex type camera that has a quick return mirror and observes a subject through a viewfinder optical system, it can achieve the same effect as the camera 1.

Next, an outline of a method for manufacturing the variable magnification optical system of this embodiment will be described with reference to FIG.
FIG. 35 is a flow chart showing an outline of a manufacturing method for a variable magnification optical system according to this embodiment.

The method for manufacturing a variable magnification optical system of this embodiment shown in FIG. 35 is a method for manufacturing a variable magnification optical system having a plurality of lens groups, and includes the following steps S1 to S3.

Step S1: A plurality of lens groups are prepared, and are configured so that the distance between each of the lens groups changes when the magnification is changed.
Step S2: The multiple lens groups are configured to have an object-side focusing lens group that moves when focusing, and at least one image-side focusing lens group that is positioned closer to the image side than the object-side focusing lens group and moves on a trajectory different from that of the object-side focusing lens group when focusing.
Step S3: The variable magnification optical system is made to satisfy the following conditional expressions (1) and (2).
(1) MTF1/MTF2 < 5.0
(2) 0.2 < BFw/fw < 2.0
however,
MTF1: Absolute value of the amount of movement of the object-side focusing lens group when focusing from an object at infinity to an object at a close distance in the telephoto end state MTF2: Absolute value of the amount of movement of the focusing lens group arranged closest to the object among the image-side focusing lens groups when focusing from an object at infinity to an object at a close distance in the telephoto end state BFw: Back focus of the variable magnification optical system in the wide-angle end state fw: Focal length of the variable magnification optical system in the wide-angle end state

According to the manufacturing method of the variable magnification optical system of this embodiment, it is possible to manufacture a variable magnification optical system that realizes high optical performance by effectively suppressing aberration fluctuations when changing magnification from the wide-angle end state to the telephoto end state and when focusing from an object at infinity to an object at close range, while also achieving high-speed focusing operations by making the focusing lens group smaller and lighter.

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group G6 Sixth lens group G7 Seventh lens group S Aperture stop I Image plane 1 Camera 2 Taking lens

Claims (8)

A lens group includes:
The first lens group is located closest to the object.
When the magnification is changed, the intervals between the lens groups change, and the first lens group moves.
the plurality of lens groups include an object-side focusing lens group that moves during focusing, and at least one image-side focusing lens group that is disposed closer to the image side than the object-side focusing lens group and moves during focusing along a locus different from that of the object-side focusing lens group;
the object-side focusing lens group is composed of one lens component,
At least one of the object-side focusing lens group and the image-side focusing lens group has at least one lens having negative refractive power,
An aperture stop is provided,
the object-side focusing lens group is disposed on the image side of the aperture stop,
the image-side focusing lens group is composed of one lens component,
A variable magnification optical system that satisfies the following condition:
MTF1/MTF2 < 5.0
0.2 < BFw/fw < 2.0
0.50 < | fF2 | / | f1 | < 3.80
0.350 ≦ |βWF1| / |βWF2| ≦ 2.449
0.45 < (-fFN)/|fF| < 1.70
39.0°＜ωw＜85.0°
0.40 < | fF1 | / | f1 | < 2.60
however,
MTF1: Absolute value of the amount of movement of the object-side focusing lens group when focusing from an object at infinity to an object at a close distance in the telephoto end state MTF2: Absolute value of the amount of movement of the focusing lens group arranged most to the object side among the image-side focusing lens groups when focusing from an object at infinity to an object at a close distance in the telephoto end state BFw: Back focus of the variable magnification optical system in the wide-angle end state fw: Focal length of the variable magnification optical system in the wide-angle end state fF2: Focal length of the focusing lens group arranged most to the image side among the image-side focusing lens groups f1: Focal length of the first lens group βWF1: Infinity Lateral magnification βWF2 of the object-side focusing lens group in the wide-angle end state when focusing on a distant object: Lateral magnification of the focusing lens group arranged closest to the object among the image-side focusing lens groups in the wide-angle end state when focusing on an object at infinity fFN: Focal length of the lens with the strongest negative refractive power among the lenses in the object-side focusing lens group and the image-side focusing lens group fF: Focal length of the focusing lens group with the strongest refractive power among the object-side focusing lens group and the image-side focusing lens group ωw: Half angle of view of the variable magnification optical system in the wide-angle end state fF1: Focal length of the object-side focusing lens group 2. The variable magnification optical system according to claim 1, wherein the object-side focusing lens group moves during magnification variation. The variable magnification optical system according to claim 1 or 2, wherein the focusing lens group arranged closest to the object among the image-side focusing lens groups moves during magnification change. 4. The variable magnification optical system according to claim 1, which satisfies the following condition: 1<x<x1/x2/x2/x1 ...
0.10 < |fF1|/ft < 3.00
however,
ft: focal length of the variable magnification optical system in the telephoto end state 5. The variable magnification optical system according to claim 1, which satisfies the following condition: 1<x<x1/x2/x2/x1 ...1/x2/x1/x2/x1/x1/x2/x1/x2/x1/x1/x2/x1/x1/x2
0.10 < |fF2|/ft < 3.00
however,
ft: focal length of the variable magnification optical system in the telephoto end state 6. A variable magnification optical system according to claim 1, which satisfies the following condition: 1<x<x1/x2/x2/x1 ...1/x2/x1
|βRw|/|βRt| < 4.00
however,
βRw: composite lateral magnification from the object-side focusing lens group to the image plane in the wide-angle end state when focusing on an object at infinity βRt: composite lateral magnification from the object-side focusing lens group to the image plane in the telephoto end state when focusing on an object at infinity The variable magnification optical system according to any one of claims 1 to 6, wherein the focusing lens group arranged closest to the object among the image-side focusing lens groups is composed of a single lens. An optical device having a variable magnification optical system according to any one of claims 1 to 7.

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