JP7375970B2 - Variable magnification optical system and optical equipment using the same - Google Patents

Description

The present invention relates to a variable magnification optical system and an optical device using the same.

2. Description of the Related Art Variable magnification optical systems suitable for photographic cameras, electronic still cameras, video cameras, etc. have been proposed for some time (for example, see Patent Document 1). However, conventional variable magnification optical systems have insufficient optical performance.

Japanese Patent Application Publication No. 4-293007

The variable power optical system according to the first aspect includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a second lens group having a positive refractive power, which are arranged in order from the object side. 3 lens groups and a subsequent lens group, and when changing magnification, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the third lens group changes. changes, the distance between the third lens group and the succeeding lens group changes, the succeeding lens group has a focusing lens group that moves during focusing, and the first lens group The third lens group includes a positive single lens disposed closest to the object side of the first lens group, and the third lens group includes a positive single lens disposed closest to the object side of the third lens group, and a positive single lens disposed closest to the object side of the third lens group. an aperture in the group, and the second lens group has a subgroup that satisfies the following conditional expression,
1.40<fvr/f2<2.30
1.80<f1/fw<3.50
Furthermore, the following conditional expression is satisfied.
3.20<f1/f3<5.00
However, fvr: focal length of the subgroup;
f2: focal length of the second lens group,
f1: focal length of the first lens group,
fw: focal length of the variable magnification optical system in the wide-angle end state;
f3: focal length of the third lens group.

An optical device according to a second aspect includes the variable magnification optical system described above.

FIG. 2 is a diagram showing a lens configuration of a variable magnification optical system according to a first example of the present embodiment. FIG. 2(a) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system according to the first embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIG. 4 is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of the variable power optical system according to the first example. FIG. 4(a) is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system according to the first embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIGS. 5(a), 5(b), and 5(c) show the zooming optical system according to the first embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations. FIG. 7 is a diagram showing a lens configuration of a variable magnification optical system according to a second example of the present embodiment. FIG. 7(a) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system according to the second embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIG. 7 is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of the variable magnification optical system according to the second example. FIG. 9(a) is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system according to the second embodiment, and FIG. 9(b) shows various aberrations for the rotational blur of 0.20 FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. 10(a), FIG. 10(b), and FIG. 10(c) show the zooming optical system according to the second embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations. FIG. 7 is a diagram showing a lens configuration of a variable magnification optical system according to a third example of the present embodiment. FIG. 12(a) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system according to the third embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIG. 7 is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of the variable magnification optical system according to the third example. FIG. 14(a) is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system according to the third embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIGS. 15(a), 15(b), and 15(c) show the zooming optical system according to the third embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations. FIG. 7 is a diagram showing a lens configuration of a variable magnification optical system according to a fourth example of the present embodiment. FIG. 17(a) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system according to the fourth embodiment, and FIG. 17(b) shows various aberrations for a rotational blur of 0.30° FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIG. 7 is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of the variable power optical system according to the fourth example. FIG. 19(a) is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system according to the fourth embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIGS. 20(a), 20(b), and 20(c) show the zooming optical system according to the fourth embodiment at close-range focusing in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations. FIG. 7 is a diagram showing a lens configuration of a variable magnification optical system according to a fifth example of the present embodiment. FIG. 22(a) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system according to the fifth embodiment, and FIG. 22(b) shows the aberration diagram for the rotational blur of 0.30 FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIG. 7 is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of the variable magnification optical system according to the fifth example. FIG. 24(a) is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system according to the fifth embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIGS. 25(a), 25(b), and 25(c) show the zooming optical system according to the fifth embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations. FIG. 7 is a diagram showing a lens configuration of a variable magnification optical system according to a sixth example of the present embodiment. FIG. 27(a) is a diagram showing various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system according to the sixth embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIG. 7 is a diagram of various aberrations when focusing on infinity in an intermediate focal length state of a variable power optical system according to a sixth embodiment. FIG. 29(a) is a diagram showing various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system according to the sixth embodiment, and FIG. FIG. 4 is a meridional lateral aberration diagram when blur correction is performed. FIGS. 30(a), 30(b), and 30(c) show the zooming optical system according to the sixth embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations. 1 is a diagram showing the configuration of a camera equipped with a variable magnification optical system according to the present embodiment. 3 is a flowchart showing a method for manufacturing a variable magnification optical system according to the present embodiment.

Hereinafter, a variable magnification optical system, an optical device, and an imaging device according to this embodiment will be described with reference to the drawings. As shown in FIG. 1, the variable magnification optical system ZL (1) as an example of the variable magnification optical system (zoom lens) ZL according to the present embodiment has first lenses having positive refractive power arranged in order from the object side. A subsequent lens group GR (fourth lens group G4) consisting of a lens group G1, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and at least one lens group. and a fifth lens group G5). During zooming, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the third lens group G3 changes, and the distance between the third lens group G3 and the subsequent lens group changes. The distance from GR changes. Further, the subsequent lens group GR includes a focusing lens group that moves during focusing.

The variable power optical system ZL according to the present embodiment may be the variable power optical system ZL(2) shown in FIG. 6, the variable power optical system ZL(3) shown in FIG. 11, or the variable power optical system ZL(3) shown in FIG. It may be a variable power optical system ZL(4), a variable power optical system ZL(5) shown in FIG. 21, or a variable power optical system ZL(6) shown in FIG. 26. Note that each group of the variable magnification optical system ZL(2), ZL(3), ZL(5), and ZL(6) shown in FIG. 6, FIG. 11, FIG. 21, and FIG. It is configured similarly to optical system ZL(1). In the variable magnification optical system ZL(4) shown in FIG. 16, the subsequent lens group GR is composed of the fourth lens group G4.

The variable power optical system ZL of this embodiment has at least four lens groups, and by changing the interval between each lens group during variable power, it is possible to achieve good aberration correction during variable power. Furthermore, by arranging the focusing lens group in the subsequent lens group GR, the focusing lens group can be made smaller and lighter.

With the above configuration, the variable magnification optical system ZL according to the present embodiment has a subgroup in which the second lens group G2 satisfies the following conditional expression.

1.40<fvr/f2<2.30...(1)
1.80<f1/fw<3.50...(2)
However, fvr: focal length of the subgroup,
f2: focal length of the second lens group G2,
f1: focal length of the first lens group G1,
fw: focal length of the variable magnification optical system ZL in the wide-angle end state.

Conditional expression (1) defines the appropriate range of the ratio of the focal length of the subgroup (of the second lens group G2) to the focal length of the second lens group G2. By satisfying conditional expression (1), performance deterioration when blur correction is performed can be effectively suppressed. Further, it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the value corresponding to conditional expression (1) exceeds the upper limit, the refractive power of the second lens group G2 becomes strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. By setting the upper limit of conditional expression (1) to 2.20, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (1) to 2.10.

When the corresponding value of conditional expression (1) is less than the lower limit value, the refractive power of the subgroup becomes strong, and it becomes difficult to correct eccentric coma aberration that occurs when blur correction is performed. By setting the lower limit of conditional expression (1) to 1.50, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (1) to 1.60.

Conditional expression (2) defines the appropriate range of the ratio between the focal length of the first lens group G1 and the focal length of the variable magnification optical system ZL in the wide-angle end state. By satisfying conditional expression (2), it is possible to prevent the lens barrel from increasing in size and to suppress fluctuations in various aberrations including spherical aberration when changing power from the wide-angle end state to the telephoto end state.

When the corresponding value of conditional expression (2) exceeds the upper limit, the refractive power of the first lens group G1 becomes weaker, and the lens barrel becomes larger. By setting the upper limit of conditional expression (2) to 3.30, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (2) to 3.10.

If the corresponding value of conditional expression (2) is below the lower limit value, the refractive power of the first lens group G1 becomes strong, making it difficult to correct various aberrations including spherical aberration during zooming. By setting the lower limit of conditional expression (2) to 1.90, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (2) to 2.00, and more preferably to set the lower limit of conditional expression (2) to 2.10. preferable.

It is desirable that the variable magnification optical system of this embodiment satisfies the following conditional expression (3).
3.70<f1/(-f2)<5.00...(3)

Conditional expression (3) defines the appropriate range of the ratio of the focal length of the first lens group G1 to the focal length of the second lens group G2. By satisfying conditional expression (3), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the value corresponding to conditional expression (3) exceeds the upper limit, the refractive power of the second lens group G2 becomes strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. By setting the upper limit of conditional expression (3) to 4.90, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (3) to 4.80.

When the corresponding value of conditional expression (3) is below the lower limit value, the refractive power of the first lens group G1 becomes strong, making it difficult to correct various aberrations including spherical aberration during zooming. By setting the lower limit of conditional expression (3) to 3.90, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (3) to 3.95.

It is desirable that the variable magnification optical system of this embodiment satisfies the following conditional expression (4).
3.20<f1/f3<5.00...(4)
However, f3: focal length of the third lens group G3.

Conditional expression (4) defines the appropriate range of the ratio of the focal length of the first lens group G1 to the focal length of the third lens group G3. By satisfying conditional expression (4), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the value corresponding to conditional expression (4) exceeds the upper limit, the refractive power of the third lens group G3 becomes strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. By setting the upper limit of conditional expression (4) to 4.80, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (4) to 4.60.

If the corresponding value of conditional expression (4) is below the lower limit value, the refractive power of the first lens group G1 becomes strong, making it difficult to correct various aberrations including spherical aberration during zooming. By setting the lower limit of conditional expression (4) to 3.40, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (4) to 3.60.

It is desirable that the variable magnification optical system of this embodiment satisfies the following conditional expression (5).
0.18<(-fF)/f1<0.30...(5)
However, fF: focal length of the focusing lens group.

Conditional expression (5) defines the appropriate range of the ratio of the focal length of the focusing lens group to the focal length of the first lens group G1. By satisfying conditional expression (5), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state. Further, it is possible to suppress fluctuations in various aberrations including spherical aberration when focusing from an object at infinity to an object at a short distance.

If the value corresponding to conditional expression (5) exceeds the upper limit, the refractive power of the first lens group G1 becomes strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. By setting the upper limit of conditional expression (5) to 0.29, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.28.

If the corresponding value of conditional expression (5) is below the lower limit value, the refractive power of the focusing lens group becomes strong, making it difficult to correct various aberrations including spherical aberration during focusing. By setting the lower limit of conditional expression (5) to 0.19, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (5) to 0.20.

It is desirable that the variable magnification optical system of this embodiment satisfies the following conditional expression (6).
0.84<(-f2)/f3<1.20...(6)
However, f3: focal length of the third lens group G3.

Conditional expression (6) defines the appropriate range of the ratio of the focal length of the second lens group G2 to the focal length of the third lens group G3. By satisfying conditional expression (6), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the value corresponding to conditional expression (6) exceeds the upper limit, the refractive power of the third lens group G3 becomes strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. By setting the upper limit of conditional expression (6) to 1.15, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (6) to 1.10.

If the corresponding value of conditional expression (6) is below the lower limit, the refractive power of the second lens group G2 becomes strong, making it difficult to correct various aberrations including spherical aberration during zooming. By setting the lower limit of conditional expression (6) to 0.87, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.90.

In the variable power optical system of this embodiment, it is preferable that the first lens group G1 moves toward the object side when changing power from the wide-angle end state to the telephoto end state. As a result, the total length of the lens in the wide-angle end state can be shortened, and the variable power optical system can be made smaller.

In the variable power optical system of this embodiment, the focusing lens group preferably includes at least one lens having positive refractive power and at least one lens having negative refractive power. This makes it possible to suppress variations in various aberrations including spherical aberration when focusing from an object at infinity to an object at a short distance.

In the variable magnification optical system of this embodiment, the subgroup (of the second lens group G2) may consist of a lens having negative refractive power and a lens having positive refractive power, which are arranged in order from the object side. preferable. This makes it possible to effectively suppress performance deterioration when blur correction is performed.

It is desirable that the variable magnification optical system of this embodiment satisfies the following conditional expression (7).
0.80<nN/nP<1.00 (7)
However, nN: refractive index of the lens having negative refractive power in the subgroup;
nP: refractive index of a lens with positive refractive power in the subgroup.

Conditional expression (7) defines the appropriate range of the ratio of the refractive index of the lens with negative refractive power in the subgroup (of the second lens group G2) to the refractive index of the lens with positive refractive power in the subgroup. It stipulates that By satisfying conditional expression (7), performance deterioration when blur correction is performed can be effectively suppressed.

When the corresponding value of conditional expression (7) exceeds the upper limit, the refractive index of the lens with positive refractive power in the subgroup becomes low, making it difficult to correct eccentric coma aberration that occurs when performing blur correction. It becomes difficult. By setting the upper limit of conditional expression (7) to 0.98, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (7) to 0.96.

When the corresponding value of conditional expression (7) is less than the lower limit value, the refractive index of the lens having negative refractive power in the subgroup becomes low, making it difficult to correct eccentric coma aberration that occurs when blur correction is performed. It becomes difficult. By setting the lower limit of conditional expression (7) to 0.82, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (7) to 0.84.

It is desirable that the variable magnification optical system of this embodiment satisfies the following conditional expression (8).
1.20<νN/νP<2.40 (8)
However, νN: Abbe number of the lens with negative refractive power in the subgroup,
νP: Abbe number of a lens with positive refractive power in the subgroup.

Conditional expression (8) defines the appropriate range of the ratio of the Abbe number of the lens having negative refractive power in the subgroup (of the second lens group G2) to the Abbe number of the lens having positive refractive power in the subgroup. It stipulates that By satisfying conditional expression (8), performance deterioration when blur correction is performed can be effectively suppressed.

If the corresponding value of conditional expression (8) exceeds the upper limit, the Abbe number of the lens with positive refractive power in the subgroup becomes too small, making it difficult to correct chromatic aberration that occurs when image stabilization is performed. becomes. By setting the upper limit of conditional expression (8) to 2.30, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (8) to 2.20.

If the corresponding value of conditional expression (8) is below the lower limit value, the Abbe number of the lens with negative refractive power in the subgroup becomes too small, making it difficult to correct the chromatic aberration that occurs when blur correction is performed. becomes. By setting the lower limit of conditional expression (8) to 1.30, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (8) to 1.40.

In the variable magnification optical system of this embodiment, the subgroup (of the second lens group G2) is an anti-vibration lens group that is movable so as to have a displacement component in a direction perpendicular to the optical axis in order to correct image blur. It is preferable that there be. This makes it possible to effectively suppress performance deterioration when blur correction is performed.

In the variable magnification optical system of this embodiment, the subsequent lens group GR includes a lens having negative refractive power placed on the image side of the focusing lens group, and a lens having negative refractive power placed on the image side of the lens having negative refractive power. It is preferable to have a lens having a positive refractive power. Thereby, various aberrations including coma can be effectively corrected.

It is desirable that the variable magnification optical system of this embodiment satisfies the following conditional expression (9).
0.70<(-fN)/fP<2.00...(9)
However, fN: focal length of a lens with negative refractive power arranged on the image side of the focusing lens group;
fP: Focal length of a lens with positive refractive power placed on the image side of a lens with negative refractive power.

Conditional expression (9) is based on the focal length of the lens with negative refractive power placed on the image side of the focusing lens group, and the focal length of the lens with negative refractive power placed on the image side of the focusing lens group ( ) defines the appropriate range of the ratio to the focal length of the lens having positive refractive power. By satisfying conditional expression (9), various aberrations including coma can be effectively corrected.

If the corresponding value of conditional expression (9) exceeds the upper limit, the refractive power of the lens with positive refractive power disposed on the image side of the focusing lens group becomes strong, making it difficult to correct coma aberration. . By setting the upper limit of conditional expression (9) to 1.90, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (9) to 1.80.

When the corresponding value of conditional expression (9) is below the lower limit value, the refractive power of the lens with negative refractive power arranged on the image side of the focusing lens group becomes strong, making it difficult to correct coma aberration. . By setting the lower limit of conditional expression (9) to 0.80, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.90.

The optical device and imaging device of this embodiment are configured to include the variable magnification optical system configured as described above. As a specific example, a camera (corresponding to the imaging device of the present invention) equipped with the variable magnification optical system ZL will be described with reference to FIG. 31. As shown in FIG. 31, this camera 1 has a lens assembly configuration in which a photographic lens 2 is replaceable, and this photographic lens 2 is provided with a variable magnification optical system having the above-described configuration. That is, the photographic lens 2 corresponds to the optical device of the present invention. camera 1
is a digital camera, and light from an object (subject) (not shown) is condensed by a photographing lens 2 and reaches an image sensor 3. Thereby, light from the subject is captured by the image sensor 3 and recorded in a memory (not shown) as a subject image. In this way, the photographer can photograph the subject using the camera 1. Note that this camera may be a mirrorless camera or a single-lens reflex camera with a quick return mirror.

With the above configuration, the camera 1 in which the variable magnification optical system ZL is mounted on the photographing lens 2 can achieve high-speed AF and AF without increasing the size of the lens barrel by making the focusing lens group smaller and lighter. Quietness can be achieved. Furthermore, aberration fluctuations during zooming from the wide-angle end state to the telephoto end state as well as aberration fluctuations during focusing from an object at infinity to a close object can be suppressed to achieve good optical performance.

Next, with reference to FIG. 32, a method for manufacturing the above-mentioned variable magnification optical system ZL will be outlined. First, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a subsequent lens group. GR (step ST1). During zooming, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the third lens group G3 changes, and the distance between the third lens group G3 and the subsequent lens group G3 changes. It is configured so that the distance from the lens group GR changes (step ST2). Further, the subsequent lens group GR is configured to include a focusing lens group that moves during focusing (step ST3). Furthermore, each lens is arranged within the lens barrel so that the second lens group G2 has at least a partial group that satisfies the above conditional expressions (1) and (2) (step ST4).

Hereinafter, a variable magnification optical system (zoom lens) ZL according to an example of the present embodiment will be described based on the drawings. 1, 6, 11, 16, 21, and 26 show the configuration and refractive power distribution of the variable magnification optical system ZL {ZL(1) to ZL(6)} according to the first to sixth embodiments. FIG. The lower part of the cross-sectional view of the variable magnification optical system ZL(1) to ZL(6) shows the movement of each lens group along the optical axis when changing the magnification from the wide-angle end state (W) to the telephoto end state (T). Directions are indicated by arrows. Furthermore, the direction in which the focusing lens group moves when focusing from infinity to a close object is indicated by an arrow along with the word "focus."

1, FIG. 6, FIG. 11, FIG. 16, FIG. 21, and FIG. 26, each lens group is represented by a combination of a symbol G and a number, and each lens is represented by a combination of a symbol L and a number. In this case, in order to prevent the types and numbers of codes and numbers from becoming large and complicated, lens groups and the like are expressed using combinations of codes and numbers independently for each embodiment. Therefore, even if the same combination of symbols and numbers is used between the embodiments, it does not mean that they have the same configuration.

Tables 1 to 6 are shown below, of which Table 1 is the first example, Table 2 is the second example, Table 3 is the third example, Table 4 is the fourth example, and Table 5 is the fourth example. Embodiment 5, Table 6 is a table showing each specification data in the sixth embodiment. In each example, the d-line (wavelength λ=587.6 nm) and the g-line (wavelength λ=435.8 nm) are selected as targets for calculating aberration characteristics.

In the [Lens specifications] table, the surface number indicates the order of the optical surfaces from the object side along the direction of propagation of the light ray, and R is the radius of curvature of each optical surface (the surface whose center of curvature is located on the image side). ), D is the surface spacing that is the distance on the optical axis from each optical surface to the next optical surface (or image surface), nd is the refractive index of the material of the optical member for the d-line, and νd is the optical The Abbe number based on the d-line of the material of the member is shown. The object plane indicates the object plane, the radius of curvature "∞" indicates a plane or an aperture, (diaphragm S) indicates the aperture stop S, and the image plane indicates the image plane I, respectively. The description of the refractive index of air nd=1.00000 is omitted.

In the [Various data] table, f is the focal length of the entire lens system, FNO is the F number, 2ω is the angle of view (unit is ° (degree), ω is the half angle of view), and Ymax is the maximum image height. show. TL is the distance obtained by adding BF to the distance from the frontmost surface of the lens on the optical axis to the final surface of the lens when focusing on infinity, and BF is the distance from the final surface of the lens on the optical axis when focusing on infinity. The distance to surface I (back focus) is shown. Note that these values are shown for each zooming state at the wide-angle end (W), intermediate focal length (M), and telephoto end (T).

The [Variable Interval Data] table shows the surface spacing for surface numbers for which the surface spacing is "variable" in the table showing [Lens Specifications]. Here, the surface spacing in each zooming state at the wide-angle end (W), intermediate focal length (M), and telephoto end (T) is shown for infinity and short distance focusing, respectively.

In the [Lens Group Data] table, the starting surface (the surface closest to the object) and focal length of each of the first to fifth lens groups (or fourth lens group) are shown.

The table of [Values corresponding to conditional expressions] shows values corresponding to the above conditional expressions (1) to (9).

Below, in all specification values, the focal length f, radius of curvature R, surface spacing D, and other lengths are generally expressed in mm unless otherwise specified, but the optical system is proportionally enlarged. Alternatively, even if the optical performance is proportionally reduced, the same optical performance can be obtained, so the present invention is not limited to this.

The description of the tables up to this point is common to all embodiments, and repeated description below will be omitted.

(First example)
A first example will be described using FIGS. 1 to 5 and Table 1. FIG. 1 is a diagram showing a lens configuration of a variable power optical system according to a first example of this embodiment. The variable magnification optical system ZL(1) according to the first embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a refractive power of , a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions shown by the arrows in FIG. 1, respectively. In this embodiment, the fourth lens group G4 and the fifth lens group G5 constitute the subsequent lens group GR. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this is the same in all the examples below.

The first lens group G1 consists of a positive meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, and a double-convex positive lens L13 arranged in order from the object side. Consists of a lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconvex positive lens L22, a biconcave negative lens L23, and a biconcave negative lens L21. It is composed of a lens L24 and a cemented negative lens consisting of a positive meniscus lens L25 with a convex surface facing the object side.

The third lens group G3 includes a double-convex positive lens L31, a double-convex positive lens L32, and a double-concave negative lens L33, which are arranged in order from the object side, and a cemented positive lens, and an aperture stop S. It is composed of a cemented positive lens consisting of a negative meniscus lens L34 with a convex surface facing the object side and a biconvex positive lens L35, and a biconvex positive lens L36.

The fourth lens group G4 includes a positive meniscus lens L41 with a concave surface facing the object side and a biconcave negative lens L42, which are arranged in order from the object side.

The fifth lens group G5 is composed of a negative meniscus lens L51 with a concave surface facing the object side and a positive meniscus lens L52 with a convex surface facing the object side, which are arranged in order from the object side. An image plane I is arranged on the image side of the fifth lens group G5.

In the variable magnification optical system ZL(1) according to the first embodiment, the entire fourth lens group G4 constitutes a focusing lens group, and by moving the entire fourth lens group G4 in the image plane direction, Focusing is performed from a distant object to a near-distance object. Further, in the variable magnification optical system ZL(1) according to the first embodiment, the cemented negative lens consisting of the negative lens L24 and the positive meniscus lens L25 of the second lens group G2 is a shield movable in a direction perpendicular to the optical axis. It constitutes a oscillating lens group (subgroup) and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

In addition, to correct rotational blur at an angle θ with a lens where the focal length of the entire system is f and the image stabilization coefficient (the ratio of the amount of image movement on the imaging plane to the amount of movement of the movable lens group in blur correction) is K. In this case, it is sufficient to move the moving lens group for blur correction by (f·tanθ)/K in a direction perpendicular to the optical axis. In the wide-angle end state of the first embodiment, the anti-vibration coefficient is 0.97 and the focal length is 72.1 mm, so the amount of movement of the anti-vibration lens group to correct rotational shake of 0.30° is It is 0.39 mm. In the telephoto end state of the first example, the vibration isolation coefficient is 2.01 and the focal length is 292.0mm, so the amount of movement of the vibration isolation lens group to correct a rotational shake of 0.20° is It is 0.51 mm.

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

(Table 1)
[Lens specifications]
Surface number R D nd νd
object surface ∞
1 121.1094 4.980 1.48749 70.31
2 474.6427 0.200
3 104.9110 1.700 1.83400 37.18
4 63.9583 9.069 1.49700 81.73
5 -1816.1542 Variable
6 153.9285 1.000 1.83400 37.18
7 37.0130 9.180
8 41.8122 5.321 1.80518 25.45
9 -148.0087 1.552
10 -153.0936 1.000 1.90366 31.27
11 74.4958 4.888
12 -65.0702 1.000 1.69680 55.52
13 35.9839 3.310 1.83400 37.18
14 121.5659 Variable
15 85.1793 3.534 1.80400 46.60
16 -101.3301 0.200
17 38.9890 5.033 1.49700 81.73
18 -62.2191 1.200 1.95000 29.37
19 378.6744 1.198
20 ∞ 19.885 (Aperture S)
21 44.8832 1.200 1.85026 32.35
22 20.5002 4.485 1.51680 63.88
23 -586.4581 0.200
24 64.4878 2.563 1.62004 36.40
25 -357.2881 Variable
26 -801.6030 2.383 1.80518 25.45
27 -50.3151 1.298
28 -57.1873 1.000 1.77250 49.62
29 26.1668 Variable
30 -21.0000 1.300 1.77250 49.62
31 -28.8136 0.200
32 58.9647 3.137 1.62004 36.40
33 524.5289 BF
Image plane ∞
[Various data]
Magnification ratio 4.05
WMT
f 72.1 99.9 292.0
FNO 4.57 4.79 5.88
2ω 33.24 23.82 8.24
Ymax 21.60 21.60 21.60
TL 191.32 204.14 241.16
BF 38.52 42.04 60.52
[Variable interval data]
W M T W M T
Infinity Infinity Infinity Close distance Close distance Close distance
d5 2.000 22.163 69.630 2.000 22.163 69.630
d14 41.783 30.929 2.000 41.783 30.929 2.000
d25 2.000 3.259 2.000 2.462 3.867 3.166
d29 14.999 13.740 14.999 14.538 13.133 13.833
[Lens group data]
Group starting plane focal length
G1 1 167.635
G2 6 -39.933
G3 15 37.727
G4 26 -36.765
G5 30 2825.740
[Conditional expression corresponding value]
Conditional expression (1) fvr/f2=1.807
Conditional expression (2) f1/fw=2.325
Conditional expression (3) f1/(-f2)=4.198
Conditional expression (4) f1/f3=4.443
Conditional expression (5) (-fF)/f1=0.219
Conditional expression (6) (-f2)/f3=1.058
Conditional expression (7) nN/nP=0.925
Conditional expression (8) νN/νP=1.493
Conditional expression (9) (-fN)/fP=1.011

FIGS. 2(a) and 2(b) are diagrams of various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system having an image stabilization function according to the first embodiment, and 0.30° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIG. 3 is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of the variable magnification optical system having an image stabilization function according to the first embodiment. 4(a) and 4(b) are diagrams of various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system having an image stabilization function according to the first embodiment, and 0.20° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIGS. 5(a), 5(b), and 5(c) show the zooming optical system according to the first embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations.

In each of the aberration diagrams in FIGS. 2 to 5, FNO represents the F number, NA represents the numerical aperture, and Y represents the image height. In addition, spherical aberration diagrams show the F number or numerical aperture value corresponding to the maximum aperture, astigmatism diagrams and distortion aberration diagrams each show the maximum image height, and coma aberration diagrams show the value of each image height. . d indicates the d-line (wavelength λ=587.6 nm), and g indicates the g-line (wavelength λ=435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Note that in the aberration diagrams of each example shown below, the same symbols as in this example are used, and overlapping explanations will be omitted.

From the various aberration diagrams, it can be seen that the variable magnification optical system according to the first embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing at close range. It can be seen that the lens also has excellent imaging performance.

(Second example)
A second example will be described using FIGS. 6 to 10 and Table 2. FIG. 6 is a diagram showing a lens configuration of a variable magnification optical system according to a second example of this embodiment. The variable magnification optical system ZL(2) according to the second embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a refractive power of , a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a negative refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions shown by the arrows in FIG. 6, respectively. In this embodiment, the fourth lens group G4 and the fifth lens group G5 constitute the subsequent lens group GR.

The first lens group G1 consists of a positive meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, and a double-convex positive lens L13 arranged in order from the object side. Consists of a lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens L21. It is composed of a cemented negative lens consisting of a concave negative lens L24 and a positive meniscus lens L25 with a convex surface facing the object side.

The third lens group G3 includes a double-convex positive lens L31, a double-convex positive lens L32, and a double-concave negative lens L33, which are arranged in order from the object side, and a cemented positive lens, and an aperture stop S. It is composed of a cemented negative lens consisting of a negative meniscus lens L34 with a convex surface facing the object side and a positive meniscus lens L35 with a convex surface facing the object side, and a biconvex positive lens L36.

The fourth lens group G4 includes a positive meniscus lens L41 with a concave surface facing the object side and a biconcave negative lens L42, which are arranged in order from the object side.

The fifth lens group G5 is composed of a negative meniscus lens L51 with a concave surface facing the object side and a positive meniscus lens L52 with a convex surface facing the object side, which are arranged in order from the object side. Fifth
An image plane I is arranged on the image side of the lens group G5.

In the variable magnification optical system ZL(2) according to the second embodiment, the entire fourth lens group G4 constitutes a focusing lens group, and by moving the entire fourth lens group G4 in the image plane direction, Focusing is performed from a distant object to a close object. Furthermore, in the variable magnification optical system ZL(2) according to the second embodiment, the cemented negative lens consisting of the negative lens L24 and the positive meniscus lens L25 of the second lens group G2 is a shield movable in a direction perpendicular to the optical axis. It constitutes a oscillating lens group (subgroup) and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

In addition, to correct rotational blur at an angle θ with a lens where the focal length of the entire system is f and the image stabilization coefficient (the ratio of the amount of image movement on the imaging plane to the amount of movement of the movable lens group in blur correction) is K. In this case, it is sufficient to move the moving lens group for blur correction by (f·tanθ)/K in a direction perpendicular to the optical axis. In the wide-angle end state of the second embodiment, the anti-vibration coefficient is 0.93 and the focal length is 72.1 mm, so the amount of movement of the anti-vibration lens group to correct a rotational shake of 0.30° is It is 0.41 mm. In the telephoto end state of the second example, the image stabilization coefficient is 1.90 and the focal length is 292.0 mm, so the amount of movement of the image stabilization lens group to correct a rotational shake of 0.20° is It is 0.54 mm.

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

(Table 2)
[Lens specifications]
Surface number R D nd νd
object surface ∞
1 114.5391 5.639 1.48749 70.31
2 663.8041 0.200
3 103.9783 1.700 1.83400 37.18
4 62.4686 8.805 1.49700 81.73
5 -43979.1830 Variable
6 146.6152 1.000 1.77250 49.62
7 35.8241 11.693
8 37.5245 4.696 1.68893 31.16
9 -254.6834 1.000 1.83400 37.18
10 64.6045 5.066
11 -60.5874 1.000 1.56883 56.00
12 39.1203 2.952 1.75520 27.57
13 93.1442 Variable
14 92.3597 3.688 1.80400 46.60
15 -87.7395 0.200
16 36.8528 5.291 1.49700 81.73
17 -63.3187 1.200 1.95000 29.37
18 264.8384 1.289
19 ∞ 19.911 (Aperture S)
20 52.0583 1.200 1.85026 32.35
21 20.7485 3.983 1.51680 63.88
22 439.3463 0.200
23 64.0215 2.788 1.62004 36.40
24 -130.2911 Variable
25 -343.5287 2.371 1.80518 25.45
26 -47.6881 1.474
27 -51.9782 1.000 1.77250 49.62
28 29.6298 Variable
29 -21.0360 1.300 1.60300 65.44
30 -30.1613 0.200
31 64.8879 2.981 1.57501 41.51
32 614.9077 BF
Image plane ∞
[Various data]
Magnification ratio 4.05
WMT
f 72.1 99.9 292.0
FNO 4.59 4.76 5.87
2ω 33.22 23.72 8.22
Ymax 21.60 21.60 21.60
TL 191.32 205.16 240.15
BF 38.52 41.03 60.02
[Variable interval data]
W M T W M T
Infinity Infinity Infinity Close distance Close distance Close distance
d5 2.000 23.304 67.717 2.000 23.304 67.717
d13 40.383 30.413 2.000 40.383 30.413 2.000
d24 2.000 3.305 2.001 2.487 3.962 3.248
d28 15.588 14.284 15.587 15.101 13.626 14.340
[Lens group data]
Group starting plane focal length
G1 1 161.728
G2 6 -38.469
G3 14 38.469
G4 25 -39.083
G5 29 -12107.081
[Conditional expression corresponding value]
Conditional expression (1) fvr/f2=2.028
Conditional expression (2) f1/fw=2.243
Conditional expression (3) f1/(-f2)=4.204
Conditional expression (4) f1/f3=4.204
Conditional expression (5) (-fF)/f1=0.242
Conditional expression (6) (-f2)/f3=1.000
Conditional expression (7) nN/nP=0.894
Conditional expression (8) νN/νP=2.031
Conditional expression (9) (-fN)/fP=0.968

7(a) and 7(b) are diagrams of various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system having an image stabilization function according to the second embodiment, and 0.30° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIG. 8 is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of the variable magnification optical system having an image stabilization function according to the second embodiment. 9(a) and 9(b) are diagrams of various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system having an image stabilization function according to the second embodiment, and 0.20° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. 10(a), FIG. 10(b), and FIG. 10(c) show the zooming optical system according to the second embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations.

From the various aberration diagrams, it can be seen that the variable magnification optical system according to the second embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing at close range. It can be seen that the lens also has excellent imaging performance.

(Third example)
The third example will be explained using FIGS. 11 to 15 and Table 3. FIG. 11 is a diagram showing a lens configuration of a variable power optical system according to a third example of this embodiment. The variable magnification optical system ZL(3) according to the third embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a refractive power of , a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions indicated by arrows in FIG. 11, respectively. In this embodiment, the fourth lens group G4 and the fifth lens group G5 constitute the subsequent lens group GR.

The first lens group G1 includes a biconvex positive lens L11 arranged in order from the object side, 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. configured.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens L21. It is composed of a cemented negative lens consisting of a concave negative lens L24 and a positive meniscus lens L25 with a convex surface facing the object side.

The third lens group G3 includes a double-convex positive lens L31, a double-convex positive lens L32, and a double-concave negative lens L33, which are arranged in order from the object side, and a cemented positive lens, and an aperture stop S. It is composed of a cemented positive lens consisting of a negative meniscus lens L34 with a convex surface facing the object side and a double convex positive lens L35.

The fourth lens group G4 includes a positive meniscus lens L41 with a concave surface facing the object side and a biconcave negative lens L42, which are arranged in order from the object side.

The fifth lens group G5 is composed of a negative meniscus lens L51 with a concave surface facing the object side and a biconvex positive lens L52, which are arranged in order from the object side. An image plane I is arranged on the image side of the fifth lens group G5.

In the variable magnification optical system ZL(3) according to the third embodiment, the entire fourth lens group G4 constitutes a focusing lens group, and by moving the entire fourth lens group G4 toward the image plane, Focusing is performed from a distant object to a near-distance object. Further, in the variable power optical system ZL(3) according to the third embodiment, the cemented negative lens consisting of the negative lens L24 and the positive meniscus lens L25 of the second lens group G2 is a shield movable in a direction perpendicular to the optical axis. It constitutes a oscillating lens group (subgroup) and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

In addition, to correct rotational blur at an angle θ with a lens where the focal length of the entire system is f and the image stabilization coefficient (the ratio of the amount of image movement on the imaging plane to the amount of movement of the movable lens group in blur correction) is K. In this case, it is sufficient to move the moving lens group for blur correction by (f·tanθ)/K in a direction perpendicular to the optical axis. In the wide-angle end state of the third embodiment, the anti-vibration coefficient is 0.96 and the focal length is 72.1 mm, so the amount of movement of the anti-vibration lens group to correct rotational shake of 0.30° is It is 0.39 mm. In the telephoto end state of the third embodiment, the vibration isolation coefficient is 2.00 and the focal length is 292.0mm, so the amount of movement of the vibration isolation lens group to correct a rotational shake of 0.20° is 0.51
It is mm.

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

(Table 3)
[Lens specifications]
Surface number R D nd νd
object surface ∞
1 268.8673 3.827 1.48749 70.31
2 -1922.6559 0.200
3 111.5860 1.700 1.62004 36.40
4 61.6123 8.761 1.49700 81.73
5 -1745.4439 Variable
6 124.2629 1.000 1.77250 49.62
7 34.3759 7.147
8 35.3149 5.189 1.60342 38.03
9 -190.5775 1.000 1.77250 49.62
10 75.4448 4.904
11 -65.2960 1.000 1.67003 47.14
12 37.2634 3.301 1.80518 25.45
13 119.9726 Variable
14 80.9765 3.968 1.77250 49.62
15 -78.4621 0.200
16 33.2120 5.701 1.49700 81.73
17 -56.7466 1.200 1.85026 32.35
18 108.8392 1.685
19 ∞ 18.569 (Aperture S)
20 40.1917 1.200 1.85026 32.35
21 18.3878 4.752 1.54814 45.79
22 -98.0255 Variable
23 -121.4042 2.367 1.75520 27.57
24 -36.6433 2.111
25 -37.5895 1.000 1.77250 49.62
26 35.8631 Variable
27 -21.0000 1.300 1.60311 60.69
28 -30.2149 0.200
29 95.7916 3.938 1.67003 47.14
30 -115.9256 BF
Image plane ∞
[Various data]
Magnification ratio 4.05
WMT
f 72.1 99.9 292.0
FNO 4.61 4.79 5.87
2ω 33.52 23.90 8.28
Ymax 21.60 21.60 21.60
TL 191.32 207.98 243.25
BF 38.52 41.37 61.52
[Variable interval data]
W M T W M T
Infinity Infinity Infinity Close distance Close distance Close distance
d5 2.000 25.429 72.273 2.000 25.429 72.273
d13 43.342 33.718 2.000 43.342 33.718 2.000
d22 2.000 3.210 3.710 2.512 3.900 5.147
d26 19.235 18.025 17.525 18.723 17.335 16.088
[Lens group data]
Group starting plane focal length
G1 1 169.647
G2 6 -39.988
G3 14 38.817
G4 23 -37.515
G5 27 207.702
[Conditional expression corresponding value]
Conditional expression (1) fvr/f2=1.860
Conditional expression (2) f1/fw=2.353
Conditional expression (3) f1/(-f2)=4.242
Conditional expression (4) f1/f3=4.370
Conditional expression (5) (-fF)/f1=0.221
Conditional expression (6) (-f2)/f3=1.030
Conditional expression (7) nN/nP=0.925
Conditional expression (8) νN/νP=1.852
Conditional expression (9) (-fN)/fP=1.529

12(a) and 12(b) are diagrams of various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system having an image stabilization function according to the third embodiment, and 0.30° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIG. 13 is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of a variable magnification optical system having an image stabilization function according to the third embodiment. FIGS. 14(a) and 14(b) are diagrams of various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system having an image stabilization function according to the third embodiment, and 0.20° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIGS. 15(a), 15(b), and 15(c) show the zooming optical system according to the third embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations.

From the various aberration diagrams, it can be seen that the variable magnification optical system according to the third embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and furthermore, when focusing at close range, It can be seen that the lens also has excellent imaging performance.

(Fourth example)
The fourth example will be described using FIGS. 16 to 20 and Table 4. FIG. 16 is a diagram showing a lens configuration of a variable magnification optical system according to a fourth example of this embodiment. The variable magnification optical system ZL(4) according to the fourth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a refractive power of , and a fourth lens group G4 having a negative refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fourth lens groups G1 to G4 move in the directions indicated by arrows in FIG. 16, respectively. In this embodiment, the fourth lens group G4 constitutes the subsequent lens group GR.

The first lens group G1 is composed of a biconvex positive lens L11 arranged in order from the object side, and a cemented positive lens consisting of a negative meniscus lens L12 with a convex surface facing the object side and a biconvex L13. Ru.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens L21. It is composed of a cemented negative lens consisting of a concave negative lens L24 and a positive meniscus lens L25 with a convex surface facing the object side.

The third lens group G3 includes a double-convex positive lens L31, a double-convex positive lens L32, and a double-concave negative lens L33, which are arranged in order from the object side, and a cemented positive lens, and an aperture stop S. It is composed of a cemented positive lens consisting of a negative meniscus lens L34 with a convex surface facing the object side and a double convex positive lens L35.

The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L41 with a concave surface facing the object side, a biconcave negative lens L42, a negative meniscus lens L43 with a concave surface facing the object side, and a biconcave negative lens L43 with a concave surface facing the object side. It is composed of a convex positive lens L44. An image plane I is arranged on the image side of the fourth lens group G4.

In the variable power optical system ZL(4) according to the fourth embodiment, the positive meniscus lens L41 and the negative lens L42 of the fourth lens group G4 constitute a focusing lens group, and the positive meniscus lens L41 and the negative lens L42 of the fourth lens group G4 constitute a focusing lens group. By moving the negative lens L42 in the image plane direction, focusing from a long-distance object to a short-distance object is performed. Furthermore, in the variable magnification optical system ZL(4) according to the fourth embodiment, the cemented negative lens consisting of the negative lens L24 and the positive meniscus lens L25 of the second lens group G2 is a shield movable in a direction perpendicular to the optical axis. It constitutes a oscillating lens group (subgroup) and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

In addition, to correct rotational blur at an angle θ with a lens where the focal length of the entire system is f and the image stabilization coefficient (the ratio of the amount of image movement on the imaging plane to the amount of movement of the movable lens group in blur correction) is K. In this case, it is sufficient to move the moving lens group for blur correction by (f·tanθ)/K in a direction perpendicular to the optical axis. In the wide-angle end state of the fourth example, the anti-vibration coefficient is 1.05 and the focal length is 72.1 mm, so the amount of movement of the anti-vibration lens group to correct rotational shake of 0.30° is It is 0.36 mm. In the telephoto end state of the fourth example, the image stabilization coefficient is 2.20 and the focal length is 292.0 mm, so the amount of movement of the image stabilization lens group to correct a rotational shake of 0.20° is It is 0.46 mm.

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

(Table 4)
[Lens specifications]
Surface number R D nd νd
object surface ∞
1 384.8872 4.307 1.48749 70.31
2 -459.3665 0.200
3 108.5471 1.700 1.62004 36.40
4 59.1633 8.722 1.49700 81.73
5 -3828.8091 Variable
6 116.0785 1.000 1.77250 49.62
7 33.3782 6.789
8 34.8547 5.123 1.64769 33.73
9 -166.2311 1.000 1.80400 46.60
10 68.6485 5.021
11 -58.3172 1.000 1.66755 41.87
12 33.1524 3.543 1.80518 25.45
13 108.5224 Variable
14 80.6236 4.111 1.77250 49.62
15 -73.7947 0.200
16 32.8485 5.846 1.49700 81.73
17 -53.4390 1.200 1.85026 32.35
18 100.1735 1.748
19 ∞ 17.032 (Aperture S)
20 45.6071 1.200 1.80100 34.92
21 18.9488 5.048 1.54814 45.79
22 -90.5382 variable
23 -106.0821 2.387 1.72825 28.38
24 -35.2284 2.066
25 -36.8890 1.000 1.77250 49.62
26 46.9619 Variable
27 -21.5153 1.300 1.60311 60.69
28 -31.7338 0.200
29 126.4587 3.612 1.77250 49.62
30 -132.9868 BF
Image plane ∞
[Various data]
Magnification ratio 4.05
WMT
f 72.1 99.9 292.0
FNO 4.60 4.77 5.88
2ω 33.56 23.82 8.26
Ymax 21.60 21.60 21.60
TL 192.32 210.67 244.12
BF 38.52 40.08 57.94
[Variable interval data]
W M T W M T
Infinity Infinity Infinity Close distance Close distance Close distance
d5 2.000 25.713 69.580 2.000 25.713 69.580
d13 40.783 32.701 2.000 40.783 32.701 2.000
d22 2.000 3.163 5.584 2.559 3.917 7.234
d26 23.661 23.661 23.661 23.103 22.908 22.012
[Lens group data]
Group starting plane focal length
G1 1 164.404
G2 6 -37.386
G3 14 38.634
G4 23 -61.380
[Conditional expression corresponding value]
Conditional expression (1) fvr/f2=1.802
Conditional expression (2) f1/fw=2.280
Conditional expression (3) f1/(-f2)=4.397
Conditional expression (4) f1/f3=4.255
Conditional expression (5) (-fF)/f1=0.268
Conditional expression (6) (-f2)/f3=0.968
Conditional expression (7) nN/nP=0.924
Conditional expression (8) νN/νP=1.645
Conditional expression (9) (-fN)/fP=1.378

17(a) and 17(b) are diagrams of various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system having an image stabilization function according to the fourth embodiment, and 0.30° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIG. 18 is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of a variable magnification optical system having an image stabilization function according to a fourth embodiment. 19(a) and 19(b) are diagrams of various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system having an image stabilization function according to the fourth embodiment, and 0.20° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIGS. 20(a), 20(b), and 20(c) show the zooming optical system according to the fourth embodiment at close-range focusing in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations.

From the various aberration diagrams, it can be seen that the variable magnification optical system according to the fourth example has excellent imaging performance by correcting various aberrations well from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing at close range. It can be seen that the lens also has excellent imaging performance.

(Fifth example)
The fifth example will be explained using FIGS. 21 to 25 and Table 5. FIG. 21 is a diagram showing a lens configuration of a variable magnification optical system according to a fifth example of this embodiment. The variable magnification optical system ZL(5) according to the fifth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a second lens group G2 having a negative refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a refractive power of , a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions indicated by arrows in FIG. 21, respectively. In this embodiment, the fourth lens group G4 and the fifth lens group G5 constitute the subsequent lens group GR.

The first lens group G1 is a cemented positive lens consisting of a biconvex positive lens L11, a negative meniscus lens L12 with a convex surface facing the object side, and a biconvex positive lens L13 with a biconvex surface facing the object side, arranged in order from the object side. It consists of and.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a positive meniscus lens L22 with a convex surface facing the object side, a biconcave negative lens L23, and a negative meniscus lens L22 with a convex surface facing the object side. and a cemented negative lens consisting of a positive meniscus lens L24 with a convex surface facing.

The third lens group G3 includes a double-convex positive lens L31, a double-convex positive lens L32, and a double-concave negative lens L33, which are arranged in order from the object side, and a cemented positive lens, and an aperture stop S. It is composed of a cemented positive lens consisting of a negative meniscus lens L34 with a convex surface facing the object side and a double convex positive lens L35.

The fourth lens group G4 includes a positive meniscus lens L41 with a concave surface facing the object side and a biconcave negative lens L42, which are arranged in order from the object side.

The fifth lens group G5 is composed of a negative meniscus lens L51 with a concave surface facing the object side and a biconvex positive lens L52, which are arranged in order from the object side. An image plane I is arranged on the image side of the fifth lens group G5.

In the variable magnification optical system ZL(5) according to the fifth embodiment, the entire fourth lens group G4 constitutes a focusing lens group, and by moving the entire fourth lens group G4 in the image plane direction, Focusing is performed from a distant object to a near-distance object. Further, in the variable magnification optical system ZL(5) according to the fifth embodiment, the cemented negative lens consisting of the negative lens L23 and the positive meniscus lens L24 of the second lens group G2 is a shield movable in a direction perpendicular to the optical axis. It constitutes a oscillating lens group (subgroup) and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

In addition, to correct rotational blur at an angle θ with a lens where the focal length of the entire system is f and the image stabilization coefficient (the ratio of the amount of image movement on the imaging plane to the amount of movement of the movable lens group in blur correction) is K. In this case, it is sufficient to move the moving lens group for blur correction by (f·tanθ)/K in a direction perpendicular to the optical axis. In the wide-angle end state of the fifth embodiment, the anti-vibration coefficient is 1.02 and the focal length is 72.1 mm, so the amount of movement of the anti-vibration lens group to correct rotational shake of 0.30° is It is 0.37 mm. In the telephoto end state of the fifth example, the image stabilization coefficient is 2.10 and the focal length is 292.0 mm, so the amount of movement of the image stabilization lens group to correct a rotational shake of 0.20° is It is 0.49 mm.

Table 5 below lists the values of the specifications of the optical system according to the fifth example.

(Table 5)
[Lens specifications]
Surface number R D nd νd
object surface ∞
1 494.4763 3.486 1.48749 70.31
2 -654.7200 0.200
3 104.3848 1.700 1.62004 36.40
4 60.0944 8.673 1.49700 81.73
5 -2277.9468 variable
6 131.3496 1.300 1.80400 46.60
7 35.6812 7.900
8 36.7192 2.871 1.68893 31.16
9 62.4101 4.726
10 -66.4912 1.000 1.70000 48.11
11 36.3174 3.414 1.80518 25.45
12 127.2974 Variable
13 90.0733 3.862 1.80400 46.60
14 -78.6804 0.200
15 33.8033 5.583 1.49700 81.73
16 -57.6791 1.200 1.85026 32.35
17 101.7237 1.726
18 ∞ 19.598 (Aperture S)
19 49.9975 1.200 1.85026 32.35
20 20.1023 4.713 1.54814 45.79
21 -72.4003 Variable
22 -158.4470 2.458 1.71736 29.57
23 -37.7406 1.732
24 -39.9149 1.000 1.77250 49.62
25 43.7406 Variable
26 -22.3495 1.300 1.69680 55.52
27 -32.8093 0.200
28 139.7659 3.301 1.80610 40.97
29 -141.5832 BF
Image plane ∞
[Various data]
Magnification ratio 4.05
WMT
f 72.1 99.9 292.0
FNO 4.68 4.85 5.88
2ω 33.48 23.86 8.26
Ymax 21.60 21.60 21.60
TL 192.32 208.96 243.67
BF 38.32 41.06 60.32
[Variable interval data]
W M T W M T
Infinity Infinity Infinity Close distance Close distance Close distance
d5 2.000 26.074 74.834 2.000 26.074 77.834
d12 45.487 35.318 2.000 45.487 35.318 2.000
d21 2.000 3.315 2.845 2.597 4.123 4.511
d25 21.171 19.856 20.326 20.574 19.048 18.660
[Lens group data]
Group starting plane focal length
G1 1 171.348
G2 6 -41.929
G3 13 40.969
G4 22 -45.959
G5 26 423.598
[Conditional expression corresponding value]
Conditional expression (1) fvr/f2=1.695
Conditional expression (2) f1/fw=2.377
Conditional expression (3) f1/(-f2)=4.087
Conditional expression (4) f1/f3=4.182
Conditional expression (5) (-fF)/f1=0.268
Conditional expression (6) (-f2)/f3=1.023
Conditional expression (7) nN/nP=0.942
Conditional expression (8) νN/νP=1.890
Conditional expression (9) (-fN)/fP=1.209

22(a) and 22(b) are diagrams of various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system having an image stabilization function according to the fifth embodiment, and 0.30° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIG. 23 is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of the variable magnification optical system having an image stabilization function according to the fifth embodiment. 24(a) and 24(b) are diagrams of various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system having an image stabilization function according to the fifth embodiment, and 0.20° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIGS. 25(a), 25(b), and 25(c) show the zooming optical system according to the fifth embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations.

From the various aberration diagrams, it can be seen that the variable magnification optical system according to the fifth embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing at close range. It can be seen that the lens also has excellent imaging performance.

(6th example)
The sixth example will be explained using FIGS. 26 to 30 and Table 6. FIG. 26 is a diagram showing a lens configuration of a variable magnification optical system according to Example 6 of this embodiment. The variable magnification optical system ZL(6) according to the sixth embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. It is composed of a third lens group G3 having a refractive power of , a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. When changing the magnification from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions indicated by arrows in FIG. 26, respectively. In this embodiment, the fourth lens group G4 and the fifth lens group G5 constitute the subsequent lens group GR.

The first lens group G1 includes a cemented positive lens consisting of a negative meniscus lens L11 with a convex surface facing the object side and a biconvex positive lens L12 arranged in order from the object side, and a positive meniscus lens with a convex surface facing the object side. It consists of L13.

The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, a biconcave negative lens L22, a positive meniscus lens L23 with a convex surface facing the object side, and a biconcave negative lens L23. It is composed of a lens L24 and a cemented negative lens consisting of a positive meniscus lens L25 with a convex surface facing the object side.

The third lens group G3 includes a double-convex positive lens L31, a double-convex positive lens L32, and a double-concave negative lens L33, which are arranged in order from the object side, and a cemented positive lens, and an aperture stop S. It is composed of a cemented positive lens consisting of a negative meniscus lens L34 with a convex surface facing the object side and a double convex positive lens L35.

The fourth lens group G4 includes a biconvex positive lens L41 and a biconcave negative lens L42, which are arranged in order from the object side.

The fifth lens group G5 is composed of a negative meniscus lens L51 with a concave surface facing the object side and a positive meniscus lens L52 with a convex surface facing the object side, which are arranged in order from the object side. An image plane I is arranged on the image side of the fifth lens group G5.

In the variable magnification optical system ZL(6) according to the sixth embodiment, the entire fourth lens group G4 constitutes a focusing lens group, and by moving the entire fourth lens group G4 in the image plane direction, Focusing is performed from a distant object to a near-distance object. Further, in the variable magnification optical system ZL(6) according to the sixth embodiment, the cemented negative lens consisting of the negative lens L24 and the positive meniscus lens L25 of the second lens group G2 is a shield movable in a direction perpendicular to the optical axis. It constitutes a oscillating lens group (subgroup) and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

In addition, to correct rotational blur at an angle θ with a lens where the focal length of the entire system is f and the image stabilization coefficient (the ratio of the amount of image movement on the imaging plane to the amount of movement of the movable lens group in blur correction) is K. In this case, it is sufficient to move the moving lens group for blur correction by (f·tanθ)/K in a direction perpendicular to the optical axis. In the wide-angle end state of the sixth embodiment, the anti-vibration coefficient is 1.01 and the focal length is 72.1 mm, so the amount of movement of the anti-vibration lens group to correct a rotational shake of 0.30° is It is 0.37 mm. In the telephoto end state of the sixth embodiment, the vibration isolation coefficient is 2.10 and the focal length is 292.0mm, so the amount of movement of the vibration isolation lens group to correct a rotational shake of 0.20° is It is 0.49 mm.

Table 6 below lists the values of the specifications of the optical system according to the sixth embodiment.

(Table 6)
[Lens specifications]
Surface number R D nd νd
object surface ∞
1 139.3408 1.700 1.64769 33.73
2 77.5654 9.455 1.49700 81.73
3 -496.0322 0.200
4 144.5249 3.734 1.48749 70.31
5 357.2933 Variable
6 142.3498 3.303 1.84666 23.80
7 -361.0297 1.824
8 -451.3220 1.300 1.83400 37.18
9 33.3045 7.193
10 35.8308 3.147 1.71736 29.57
11 69.2532 4.718
12 -63.1663 1.000 1.66755 41.87
13 34.7105 3.239 1.80518 25.45
14 102.2323 Variable
15 73.7312 3.697 1.77250 49.62
16 -95.2978 0.200
17 33.5557 5.512 1.49700 81.73
18 -68.5312 1.200 1.90366 31.27
19 129.3820 1.534
20 ∞ 17.193 (Aperture S)
21 40.0826 1.200 1.85026 32.35
22 17.3868 5.268 1.56732 42.58
23 -141.3282 variable
24 297.2824 2.624 1.64769 33.73
25 -42.2438 0.835
26 -48.9103 1.000 1.77250 49.62
27 31.0082 Variable
28 -22.3095 1.300 1.69680 55.52
29 -31.0148 0.200
30 73.8865 3.135 1.80100 34.92
31 3043.5154 BF
Image plane ∞
[Various data]
Magnification ratio 4.05
WMT
f 72.1 100.0 292.0
FNO 4.65 4.93 5.88
2ω 33.24 23.86 8.28
Ymax 21.60 21.60 21.60
TL 192.32 206.35 244.34
BF 38.32 42.77 60.32
[Variable interval data]
W M T W M T
Infinity Infinity Infinity Close distance Close distance Close distance
d5 2.000 22.642 74.835 2.000 22.642 74.835
d14 44.818 33.757 2.000 44.818 33.757 2.000
d23 2.000 3.329 2.024 2.604 4.116 3.661
d27 19.472 18.143 19.448 18.869 17.356 17.812
[Lens group data]
Group starting plane focal length
G1 1 176.000
G2 6 -42.283
G3 15 38.971
G4 24 -44.470
G5 28 381.600
[Conditional expression corresponding value]
Conditional expression (1) fvr/f2=1.620
Conditional expression (2) f1/fw=2.441
Conditional expression (3) f1/(-f2)=4.162
Conditional expression (4) f1/f3=4.516
Conditional expression (5) (-fF)/f1=0.253
Conditional expression (6) (-f2)/f3=1.085
Conditional expression (7) nN/nP=0.924
Conditional expression (8) νN/νP=1.645
Conditional expression (9) (-fN)/fP=1.286

27(a) and 27(b) are diagrams of various aberrations when focusing on infinity in the wide-angle end state of the variable magnification optical system having an image stabilization function according to the sixth embodiment, and 0.30° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIG. 28 is a diagram showing various aberrations when focusing on infinity in an intermediate focal length state of the variable magnification optical system having an image stabilization function according to the sixth embodiment. 29(a) and 29(b) are diagrams of various aberrations when focusing on infinity in the telephoto end state of the variable magnification optical system having an image stabilization function according to the sixth embodiment, and 0.20° FIG. 7 is a meridional transverse aberration diagram when blur correction is performed for rotational blur. FIGS. 30(a), 30(b), and 30(c) show the zooming optical system according to the sixth embodiment when focusing at close range in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. It is a diagram of various aberrations.

From the various aberration diagrams, it can be seen that the variable magnification optical system according to the sixth embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also has excellent imaging performance when focusing at close range. It can be seen that the lens also has excellent imaging performance.

According to each of the above embodiments, by making the focusing lens group smaller and lighter, it is possible to achieve high-speed AF (autofocus) and quietness during AF without increasing the size of the lens barrel. It is possible to realize a variable magnification optical system that satisfactorily suppresses aberration fluctuations when changing magnification from the telephoto end state to the telephoto end state, as well as aberration fluctuations when focusing from an object at infinity to a close object.

Here, each of the above embodiments shows one specific example of the present invention, and the present invention is not limited thereto.

Note that the following content can be appropriately adopted within a range 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, one with a four-group configuration and one with a five-group configuration are shown, but the present application is not limited to this, and the variable magnification optical system with other group configurations (for example, six groups, etc.) is shown. It is also possible to configure an optical system. Specifically, a lens or lens group may be added to the variable magnification optical system of this embodiment closest to the object side or closest to the image plane. Note that the lens group refers to a portion having at least one lens separated by an air gap that changes during zooming.

Focusing lens group refers to a section with at least one lens separated by an air gap that changes during focusing. That is, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to form a focusing lens group that focuses from an object at infinity to an object at a short distance. This focusing lens group can also be applied to autofocus, and is also suitable for driving a motor (using an ultrasonic motor or the like) for autofocus.

In each example of the variable magnification optical system of the present embodiment, a configuration having an anti-vibration function is shown, but the present application is not limited to this, and a configuration without an anti-vibration function is also possible.

The lens surface may be formed as a spherical surface, a flat surface, or an aspherical surface. It is preferable that the lens surface is spherical or flat because it facilitates lens processing and assembly adjustment and prevents deterioration of optical performance due to errors in processing and assembly adjustment. Further, even if the image plane shifts, there is little deterioration in depiction performance, which is preferable.

When the lens surface is aspherical, the aspherical surface can be an aspherical surface made by grinding, a glass molded aspherical surface made by molding glass into an aspherical shape, or a composite aspherical surface made by molding resin into an aspherical shape on the glass surface. Either is fine. Further, the lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

Although it is preferable that the aperture diaphragm is disposed in the third lens group, the role of the aperture diaphragm may be substituted by a lens frame without providing a member for the aperture diaphragm.

Each lens surface may be coated with an antireflection film having high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve optical performance with high contrast. This reduces flare and ghosting, making it possible to achieve high optical performance with high contrast.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group GR Subsequent lens group I Image plane S Aperture diaphragm

Claims (10)

It has a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a subsequent lens group arranged in order from the object side. ,
During zooming, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the distance between the third lens group and the subsequent lens changes. The distance between the group changes,
The subsequent lens group has a focusing lens group that moves during focusing,
The first lens group has a positive single lens disposed closest to the object side of the first lens group,
The third lens group has a positive single lens disposed closest to the object side of the third lens group, and an aperture within the third lens group,
The second lens group has a subgroup satisfying the following conditional expression,
1.40<fvr/f2<2.30
1.80<f1/fw<3.50
Furthermore, a variable magnification optical system that satisfies the following conditional expression.
3.20<f1/f3<5.00
However, fvr: focal length of the subgroup;
f2: focal length of the second lens group,
f1: focal length of the first lens group,
fw: focal length of the variable magnification optical system in the wide-angle end state;
f3: focal length of the third lens group. The variable power optical system according to claim 1, which satisfies the following conditional expression.
0.84<(-f2)/f3<1.20 The variable magnification optical system according to claim 1 or 2, which satisfies the following conditional expression.
0.18<(-fF)/f1<0.30
However, fF: focal length of the focusing lens group 4. The variable power optical system according to claim 1, wherein the focusing lens group includes at least one lens having positive refractive power and at least one lens having negative refractive power. 5. The variable power optical system according to claim 1, wherein the subgroup includes a lens having a negative refractive power and a lens having a positive refractive power, which are arranged in order from the object side. The variable magnification optical system according to claim 5, which satisfies the following conditional expression.
0.80<nN/nP<1.00
However, nN: the refractive index of the lens having negative refractive power in the subgroup
nP: refractive index of the lens having positive refractive power in the subgroup The variable magnification optical system according to claim 5 or 6, which satisfies the following conditional expression.
1.20<νN/νP<2.40
However, νN: Abbe number of the lens having negative refractive power in the subgroup
νP: Abbe number of the lens with positive refractive power in the subgroup The subsequent lens group includes a lens having a negative refractive power disposed on the image side of the focusing lens group, and a lens having a positive refractive power disposed on the image side of the lens having the negative refractive power. The variable power optical system according to any one of claims 1 to 6. The variable magnification optical system according to claim 8, which satisfies the following conditional expression.
0.70<(-fN)/fP<2.00
However, fN: focal length of the lens having negative refractive power disposed on the image side of the focusing lens group
fP: focal length of the lens with positive refractive power placed on the image side of the lens with negative refractive power An optical device comprising the variable magnification optical system according to any one of claims 1 to 9.

Images