JP5609386B2 - Variable magnification optical system, optical device - Google Patents

Description

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

  Conventionally, as a variable magnification optical system used for an interchangeable lens for a single-lens reflex camera or the like, many optical systems in which the lens group closest to the object side has a positive refractive power have been proposed (for example, see Patent Document 1).

JP 2008-3195 A

  If the conventional variable magnification optical system is further increased in magnification, aberration fluctuations increase, making it difficult to obtain sufficiently high optical performance.

  The present invention has been made in view of the above problems, and an object thereof is to provide a variable magnification optical system that suppresses aberration fluctuation and has high optical performance, an optical apparatus having the same, and a method for manufacturing the variable magnification optical system. To do.

In order to solve the above problems, the present invention provides:
In order from the object side along the optical axis, it becomes a first lens group having a positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
The plurality of positive lenses in the first lens group is two,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft < 0.48
However,
ndA: Refractive index νdA for the material of the plurality of positive lenses in the first lens group νdA: Abbe number fw for the material of the plurality of positive lenses in the first lens group fw: in the wide-angle end state Focal length ft of the entire zooming optical system: focal length f1 of the entire zooming optical system in the telephoto end state f1: Focal length of the first lens group
The present invention also provides:
In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
The plurality of positive lenses in the first lens group is two,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.52
0.65 <f1A / f1 <1.75
However,
ndA: refractive index with respect to d-line of the materials of the plurality of positive lenses in the first lens group
νdA: Abbe number for the d-line of the materials of the plurality of positive lenses in the first lens group
fw: focal length of the entire zoom optical system in the wide-angle end state
ft: focal length of the entire zoom optical system in the telephoto end state
f1: Focal length of the first lens group
f1A: focal lengths of the plurality of positive lenses in the first lens group
The present invention also provides:
In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.48
0.25 <Δ1 / f1 <1.10
However,
ndA: refractive index with respect to d-line of the materials of the plurality of positive lenses in the first lens group
νdA: Abbe number for the d-line of the materials of the plurality of positive lenses in the first lens group
fw: focal length of the entire zoom optical system in the wide-angle end state
ft: focal length of the entire zoom optical system in the telephoto end state
f1: Focal length of the first lens group
Δ1: Amount of movement of the first lens group with respect to the image plane from the wide-angle end state to the telephoto end state
The present invention also provides:
In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.52
0.25 <Δ1 / f1 <1.10
0.65 <f1A / f1 <1.75
However,
ndA: refractive index with respect to d-line of the materials of the plurality of positive lenses in the first lens group
νdA: Abbe number for the d-line of the materials of the plurality of positive lenses in the first lens group
fw: focal length of the entire zoom optical system in the wide-angle end state
ft: focal length of the entire zoom optical system in the telephoto end state
f1: Focal length of the first lens group
Δ1: Amount of movement of the first lens group with respect to the image plane from the wide-angle end state to the telephoto end state
f1A: focal lengths of the plurality of positive lenses in the first lens group
The present invention also provides:
In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.44
However,
ndA: refractive index with respect to d-line of the materials of the plurality of positive lenses in the first lens group
νdA: Abbe number for the d-line of the materials of the plurality of positive lenses in the first lens group
fw: focal length of the entire zoom optical system in the wide-angle end state
ft: focal length of the entire zoom optical system in the telephoto end state
f1: Focal length of the first lens group

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

  According to the present invention, it is possible to provide a variable magnification optical system that suppresses aberration fluctuation and has high optical performance, an optical apparatus having the variable magnification optical system, and a method for manufacturing the variable magnification optical system.

It is sectional drawing which shows the structure of the variable magnification optical system which concerns on 1st Example. The aberration diagrams in the infinite focus state of the variable magnification optical system according to the first example are shown, (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Show. It is sectional drawing which shows the structure of the variable magnification optical system which concerns on 2nd Example. The aberration diagrams in the infinite focus state of the variable magnification optical system according to the second example are shown, (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Show. It is sectional drawing which shows the structure of the variable magnification optical system which concerns on 3rd Example. FIG. 5A illustrates various aberration diagrams of the variable magnification optical system according to Example 3 in an infinitely focused state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Show. It is sectional drawing which shows the structure of the variable magnification optical system which concerns on 4th Example. FIG. 5A illustrates various aberration diagrams of the zoom optical system according to Example 4 in an infinitely focused state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Show. It is a figure which shows the structure of the camera provided with the variable magnification optical system which concerns on 1st Example. It is a figure which shows the manufacturing method of the variable magnification optical system of this application.

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

  The variable magnification optical system according to this embodiment includes, in order from the object side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. And the distance between the first lens group and the second lens group increases and the distance between the second lens group and the third lens group decreases during zooming from the wide-angle end state to the telephoto end state. By doing so, an optical system capable of zooming is realized, and at the same time, fluctuations in distortion due to zooming are suppressed.

In the variable magnification optical system according to the present embodiment, the first lens group includes a plurality of positive lenses that satisfy the following conditional expression (1), and the following conditional expressions (2) and (3) are satisfied. .
(1) When ndA ≧ 1.540 νdA> 66.5
When ndA <1.540 νdA> 75.0
(2) 4.75 <f1 / fw <11.00
(3) 0.28 <f1 / ft <0.52
Where ndA is the refractive index for the d-line (wavelength λ = 587.6 nm) of the plurality of positive lenses in the first lens group, and νdA is the d-line (wavelength of the plurality of positive lenses in the first lens group). Abbe number for λ = 587.6 nm), fw is the focal length of the entire zooming optical system in the wide-angle end state, ft is the focal length of the entire zooming optical system in the telephoto end state, and f1 is the focal point of the first lens group Distance.

  Conditional expression (1) defines the optimal Abbe number of the materials of the plurality of positive lenses in the first lens group, and achieves high optical performance by suppressing chromatic aberration fluctuations that occur during zooming from the wide-angle end to the telephoto end. This is a conditional expression.

  If the lower limit value of conditional expression (1) is not reached, it will be difficult to suppress fluctuations in axial chromatic aberration and lateral chromatic aberration, and it will be difficult to suppress fluctuations in secondary chromatic aberration because the material will have less anomalous dispersion. In addition, the amount of axial chromatic aberration and lateral chromatic aberration in the visible light region is particularly large at the telephoto end, and high optical performance cannot be realized.

  In order to secure the effect of the embodiment, when ndA ≧ 1.540, it is preferable to set the lower limit of conditional expression (1) to 67.5. In order to secure the effect of the embodiment, when ndA <1.540, it is preferable to set the lower limit of conditional expression (1) to 80.5.

  Conditional expression (2) defines the optimum focal length range of the first lens group, and realizes high optical performance by suppressing variations in chromatic aberration and off-axis aberration that occur during zooming from the wide-angle end to the telephoto end. This is a conditional expression.

  If the lower limit value of conditional expression (2) is not reached, the refractive power of the first lens group becomes excessively strong, making it difficult to suppress lateral chromatic aberration and off-axis aberrations, particularly astigmatism fluctuations, resulting in high optical performance. Cannot be realized.

  When the upper limit value of conditional expression (2) is exceeded, the refractive power of the first lens group becomes excessively weak, so that the amount of movement of the first lens group relative to the image plane needs to be increased in order to obtain a predetermined zoom ratio. Comes out. Then, when changing the magnification from the wide-angle end to the telephoto end, the variation in height from the optical axis through which the off-axis light beam passes becomes large, so it becomes difficult to suppress the variation in lateral chromatic aberration and off-axis aberration, particularly astigmatism, High optical performance cannot be realized.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (2) to 5.10.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (2) to 8.80. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (2) to 7.60.

  Conditional expression (3) defines the optimum focal length range of the first lens group, and realizes high optical performance by suppressing variations in chromatic aberration and off-axis aberration that occur during zooming from the wide-angle end to the telephoto end. This is a conditional expression.

  If the lower limit value of conditional expression (3) is not reached, the refractive power of the first lens group becomes excessively strong, making it difficult to suppress fluctuations in longitudinal chromatic aberration and spherical aberration, and high optical performance cannot be realized.

  If the upper limit value of conditional expression (3) is exceeded, the refractive power of the first lens group becomes excessively weak, so that the amount of movement of the first lens group relative to the image plane needs to be increased in order to obtain a predetermined zoom ratio. Comes out. Then, when changing the magnification from the wide-angle end to the telephoto end, the variation in height from the optical axis through which the off-axis light beam passes becomes large, so it becomes difficult to suppress the variation in lateral chromatic aberration and off-axis aberration, particularly astigmatism, High optical performance cannot be realized.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.31.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (3) to 0.48. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (3) to 0.44.

In addition, it is desirable that the variable magnification optical system according to the present embodiment satisfies the following conditional expression (4).
(4) 0.25 <Δ1 / f1 <1.10
However, Δ1 is the amount of movement of the first lens group with respect to the image plane from the wide-angle end state to the telephoto end state.

  Conditional expression (4) defines the optimum amount of movement of the first lens group from the wide-angle end to the telephoto end, and achieves high optical performance by suppressing variations in chromatic and off-axis aberrations that occur during zooming. This is a conditional expression.

  If the lower limit value of conditional expression (4) is not reached, the amount of movement of the first lens group becomes excessively small, so that it is necessary to increase the refractive power of the first lens group in order to obtain a predetermined zoom ratio. come. Then, when the magnification is changed from the wide-angle end to the telephoto end, the refractive power change due to the change in the height from the optical axis through which the off-axis light beam passes becomes excessively large, and therefore the lateral chromatic aberration and off-axis aberration, especially astigmatism fluctuation It is difficult to suppress this, and high optical performance cannot be realized.

  When the upper limit of conditional expression (4) is exceeded, the amount of movement of the first lens group relative to the image plane becomes excessively large, and the height from the optical axis through which the off-axis light beam passes during zooming from the wide-angle end to the telephoto end. Therefore, it becomes difficult to suppress variations in lateral chromatic aberration and off-axis aberration, particularly astigmatism, and high optical performance cannot be realized.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.36. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (4) to 0.48.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.95. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (4) to 0.85.

In addition, it is desirable that the variable magnification optical system according to the present embodiment satisfies the following conditional expression (5).
(5) 0.65 <f1A / f1 <1.75
Here, f1A is the focal length of a plurality of positive lenses in the first lens group.

  Conditional expression (5) defines the optimum focal length of each of the plurality of positive lenses in the first lens group, and achieves high optical performance by suppressing variations in chromatic aberration and off-axis aberration that occur during zooming. Conditional expression.

  If the lower limit of conditional expression (5) is not reached, the refractive power of a plurality of positive lenses becomes excessively strong, so that the variation in height from the optical axis through which the off-axis light beam passes during zooming from the wide-angle end to the telephoto end Accordingly, the change in refractive power becomes excessively large, and it becomes difficult to suppress variations in lateral chromatic aberration and off-axis aberration, particularly astigmatism, and high optical performance cannot be realized.

  When the upper limit value of conditional expression (5) is exceeded, the refractive powers of the plurality of positive lenses become relatively excessively weak, so that the refractive powers of positive lenses other than the plurality of positive lenses in the first lens group are excessively large. When the magnification is changed from the wide-angle end to the telephoto end, the refractive power change due to the height variation from the optical axis through which the off-axis light beam passes becomes excessively large, and the lateral chromatic aberration and off-axis aberration, especially astigmatism variation It is difficult to suppress this, and high optical performance cannot be realized.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.80.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (5) to 1.35.

In addition, it is desirable that the variable magnification optical system according to the present embodiment satisfies the following conditional expression (6).
(6) 1.75 <φ1A / fw <4.50
However, φ1A is an effective diameter of a plurality of positive lenses in the first lens group.

  Conditional expression (6) defines the optimum effective diameter of a plurality of positive lenses in the first lens group, and is a condition for realizing high optical performance by suppressing variations in chromatic aberration and off-axis aberration that occur during zooming. It is a formula.

  If the lower limit value of conditional expression (6) is not reached, the variation in height from the optical axis through which off-axis luminous fluxes of the plurality of positive lenses in the first lens group pass during zooming from the wide-angle end to the telephoto end is excessive. Therefore, it becomes difficult to suppress fluctuations in off-axis aberrations, particularly astigmatism, and high optical performance cannot be realized.

  If the upper limit value of conditional expression (6) is exceeded, the variation in height from the optical axis through which off-axis luminous fluxes of the plurality of positive lenses in the first lens group pass during zooming from the wide-angle end to the telephoto end is excessive. It becomes difficult to suppress fluctuations in lateral chromatic aberration and off-axis aberration, particularly astigmatism, and high optical performance cannot be realized.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (6) to 2.45.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (6) to 3.80.

  In the variable power optical system according to the present embodiment, it is desirable that the plurality of positive lenses in the first lens group be two.

  With this configuration, it is possible to suppress the thickness of the first lens unit, and from the optical axis of the off-axis light beam on the most object side surface of the first lens unit upon zooming from the wide angle end to the telephoto end. It is possible to suppress fluctuations in the height of the lens, and to suppress fluctuations in off-axis aberrations, particularly astigmatism, so that high optical performance can be realized.

In the zoom optical system according to the present embodiment, it is desirable that the first lens group has a negative lens that satisfies the following conditional expressions (7) and (8).
(7) 1.750 <ndN
(8) 28.0 <νdN <50.0
Where ndN is the refractive index of the negative lens material d-line (wavelength λ = 587.6 nm) in the first lens group, and νdN is the negative lens material d-line (wavelength λ = 58.7. Abbe number for 6 nm).

  Conditional expression (7) defines the optimum refractive index range of the negative lens in the first lens group, and obtains high optical performance by suppressing fluctuations in off-axis aberrations that occur during zooming from the wide-angle end to the telephoto end. Is a conditional expression.

  If the lower limit value of conditional expression (7) is not reached, the curvature of the surface of the negative lens in the first lens group becomes large, so that the off-axis light beam passing through the negative lens passes through the negative lens upon zooming from the wide angle end to the telephoto end. It becomes difficult to suppress off-axis aberrations, particularly astigmatism fluctuations due to height fluctuations from the optical axis, and high optical performance cannot be realized.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (7) to 1.780.

  Conditional expression (8) defines the optimum Abbe number of the material of the negative lens in the first lens group, and realizes high optical performance by suppressing chromatic aberration fluctuations that occur during zooming from the wide-angle end to the telephoto end. This is a conditional expression.

  If the lower limit value of conditional expression (8) is not reached, it is difficult to suppress fluctuations in secondary chromatic aberration during zooming from the wide-angle end to the telephoto end, and high optical performance cannot be realized.

  If the upper limit of conditional expression (8) is exceeded, if the first lens group tries to perform predetermined achromaticity, the refractive power of each positive and negative lens becomes excessively large and negative when zooming from the wide-angle end to the telephoto end. It is difficult to suppress off-axis aberrations, particularly astigmatism fluctuations due to fluctuations in height from the optical axis through which the off-axis light beam passes through the lens, and high optical performance cannot be realized.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (8) to 43.0.

  In the variable magnification optical system according to the present embodiment, it is desirable that the number of negative lenses in the first lens group is one.

  With this configuration, it is possible to suppress the thickness of the first lens unit, and from the optical axis of the off-axis light beam on the most object side surface of the first lens unit upon zooming from the wide angle end to the telephoto end. It is possible to suppress fluctuations in the height of the lens, and to suppress fluctuations in off-axis aberrations, particularly astigmatism, so that high optical performance can be realized.

In the zoom optical system according to the present embodiment, it is desirable that the third lens group has a positive lens that satisfies the following conditional expression (9).
(9) νd3> 65.5
Where νd3 is the Abbe number with respect to the d-line (wavelength λ = 587.6 nm) of the material of the positive lens in the third lens group.

  Conditional expression (9) defines the optimum Abbe number of the material of the positive lens in the third lens group, and realizes high optical performance by suppressing variation in chromatic aberration that occurs during zooming from the wide-angle end to the telephoto end. This is a conditional expression.

  If the lower limit of conditional expression (9) is not reached, it will be difficult to suppress fluctuations in axial chromatic aberration and lateral chromatic aberration, and it will be difficult to suppress fluctuations in secondary chromatic aberration because the material will have less anomalous dispersion. In addition, the amount of axial chromatic aberration and lateral chromatic aberration in the visible light region is particularly large at the telephoto end, and high optical performance cannot be realized.

  In the zoom optical system according to the present embodiment, the third lens group includes a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power in order from the object side along the optical axis. In the zooming from the wide-angle end state to the telephoto end state, it is desirable that the distance between the 31st lens group and the 32nd lens group decreases.

  With this configuration, it is possible to increase the zoom ratio of the third lens unit rather than moving the third lens unit as a single unit, and further suppress high fluctuations in spherical aberration, coma aberration, and astigmatism, resulting in high optical performance. realizable.

  In the variable magnification optical system according to the present embodiment, the third lens group includes, in order from the object side along the optical axis, a positive lens power group, a negative lens power group, a negative lens power group, and a positive lens power group. And a distance between the 31st lens group and the 32nd lens group changes upon zooming from the wide-angle end state to the telephoto end state, and the 32nd lens group and the 33rd lens group. It is desirable that the interval between and changes.

  By adopting this configuration, it is possible to suppress aberration fluctuations that occur in the third lens group rather than moving the third lens group as a unit, and in particular, high optical performance by suppressing fluctuations in spherical aberration, coma aberration, and astigmatism. Performance can be realized.

  In the zoom optical system according to the present embodiment, the distance between the thirty-first lens group and the thirty-second lens group increases during zooming from the wide-angle end state to the telephoto end state, and the thirty-second lens group and the thirty-third lens. It is desirable to reduce the distance between groups.

  With this configuration, it is possible to increase the zoom ratio of the third lens group, and it is possible to realize high optical performance while suppressing variations in spherical aberration, coma aberration, and astigmatism.

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

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

  As shown in FIG. 1, the variable magnification optical system according to the first example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side along the optical axis. And a third lens group G3 having a positive refractive power. The third lens group G3 includes, in order from the object side along the optical axis, a 31st lens group G31 having a positive refractive power, a 32nd lens group G32 having a negative refractive power, and a 33rd lens group G33 having a positive refractive power. Composed.

  When zooming from the wide-angle end state W to the telephoto end state T, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases. Thus, with respect to the image plane I, the first lens group G1 monotonously moves toward the object side, the second lens group G2 moves once toward the image side, then moves toward the object side, and the third lens group G3 Move to the object side monotonously. Further, the distance between the 31st lens group G31 and the 32nd lens group G32 is increased, and the distance between the 32nd lens group G32 and the 33rd lens group G33 is decreased, so that the 31st lens group G31 and the 32nd lens group are reduced. G32 and the 33rd lens group G33 move to the object side monotonously with respect to the image plane I. The thirty-first lens group G31 and the thirty-third lens group G33 move integrally with the image plane I.

  The aperture stop S is disposed closest to the object side of the third lens group G3 on the image side of the second lens group G2, and is configured integrally with the 31st lens group G31.

  The first lens group G1 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. It is composed of

  The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, a biconvex lens L23, a biconcave lens L24, and a biconvex lens L25. It consists of a lens. The negative meniscus lens L21 located closest to the object side in the second lens group G2 is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The thirty-first lens group G31 includes, in order from the object side along the optical axis, a biconvex lens L31, a biconvex lens L32, a cemented lens of a biconvex lens L33, and a negative meniscus lens L34 having a concave surface facing the object side. ing.

  The thirty-second lens group G32 includes, in order from the object side along the optical axis, a cemented lens of a biconcave lens L41 and a positive meniscus lens L42 having a convex surface facing the object side, and a negative meniscus lens L43 having a concave surface facing the object side. It is composed of The biconcave lens L41 located closest to the object side in the thirty-second lens group G32 is a compound aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The thirty-third lens group G33 includes, in order from the object side along the optical axis, a positive meniscus lens L51 having a concave surface directed toward the object side, a biconvex lens L52, and a cemented lens of a biconcave lens L53 and a biconvex lens L54. ing. The positive meniscus lens L51 located closest to the object side in the thirty-third lens group G33 is a glass mold aspheric lens having an aspheric lens surface on the object side. Light rays emitted from the biconvex lens L54 form an image on the image plane I.

  The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like (the same applies to the following embodiments).

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

  In (surface data) in the table, the object surface is the object surface, the surface number is the lens surface number from the object side, r is the radius of curvature, d is the surface spacing, and nd is the d-line (wavelength λ = 587.6 nm). Refractive index, νd represents the Abbe number in the d-line (wavelength λ = 587.6 nm), (variable) represents the variable surface interval, (diaphragm) represents the aperture stop S, and the image surface represents the image surface I. Note that the refractive index of air nd = 1.000 000 is omitted. Further, “∞” in the radius of curvature r column indicates a plane.

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

  In (various data), the zoom ratio is the zoom ratio of the zoom optical system, W is the wide-angle end state, M is the intermediate focal length state, T is the telephoto end state, f is the focal length of the entire system, FNO is the F number, ω is the half angle of view (unit: “°”), Y is the image height, TL is the total length of the lens system from the most object side surface of the first lens group G1 to the image surface I in the infinite focus state, and Bf is the back Focus and di each represent a variable surface interval value for surface number i.

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

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

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

(Table 1)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 186.59960 2.20000 1.834000 37.17
2 69.08900 8.80000 1.497820 82.56
3 -494.44545 0.10000
4 73.40222 6.45000 1.593190 67.87
5 2016.71160 (variable)

6 * 84.85000 0.10000 1.553890 38.09
7 74.02192 1.20000 1.834810 42.72
8 17.09747 6.95000
9 -37.97970 1.00000 1.816000 46.63
10 77.67127 0.15000
11 36.26557 5.30000 1.784720 25.68
12 -36.26557 0.80000
13 -25.69642 1.00000 1.816000 46.63
14 66.08300 2.05000 1.808090 22.79
15 -666.70366 (variable)

16 (Aperture) ∞ 1.00000
17 68.30727 3.40000 1.593190 67.87
18 -47.99596 0.10000
19 68.52367 2.45000 1.487490 70.45
20 -136.98392 0.10000
21 46.52671 4.20000 1.487490 70.45
22 -36.16400 1.00000 1.808090 22.79
23 -202.95328 (variable)

24 * -55.09840 0.20000 1.553890 38.09
25 -57.24715 0.90000 1.696800 55.52
26 28.15100 2.15000 1.728250 28.46
27 87.70856 4.35000
28 -26.69877 1.00000 1.729160 54.66
29 -76.47707 (variable)

30 * -333.89500 4.65000 1.589130 61.18
31 -24.64395 0.10000
32 31.19625 5.85000 1.487490 70.45
33 -43.38887 1.45000
34 -109.71645 1.00000 1.883000 40.77
35 20.29920 5.30000 1.548140 45.79
36 -808.81321 (Bf)
Image plane ∞

(Aspheric data)
6th surface κ = 1.0000
A4 = 3.13350E-06
A6 = 4.73080E-10
A8 = -3.40500E-11
A10 = 1.16620E-13
24th surface κ = 1.0000
A4 = 5.24030E-06
A6 = -2.00730E-09
A8 = 0.00000E + 00
A10 = 0.00000E + 00
30th surface κ = 1.0000
A4 = -1.54020E-05
A6 = 1.69500E-09
A8 = 1.34490E-11
A10 = -2.07220E-13

(Various data)
Zoom ratio 15.721
W M T
f = 18.52363 104.52143 291.21725
FNO = 3.60558 5.69344 5.89616
ω = 38.89095 7.41882 2.71146
Y = 14.20 14.20 14.20
TL = 164.74420 225.48860 251.39424
Bf = 39.44250 71.57530 83.10134

d5 2.15700 53.25650 76.94960
d15 33.80140 11.31350 2.00000
d23 3.45650 11.60170 13.04330
d29 10.58680 2.44160 1.00000

(Zoom lens group data)
Group Start surface Focal length 1 1 118.96910
2 6-15.5622
3 16 40.88868 (W)
33.90635 (M)
32.38356 (T)
31 16 27.17463
32 24-25.41506
33 30 34.39022

(Values for conditional expressions)
(1) ndA = 1.497820 (L12)
νdA = 82.56 (L12)
(1) ndA = 1.593190 (L13)
νdA = 67.87 (L13)
(2) f1 / fw = 6.423
(3) f1 / ft = 0.409
(4) Δ1 / f1 = 0.728
(5) f1A / f1 = 1.029 (L12)
(5) f1A / f1 = 1.008 (L13)
(6) φ1A / fw = 3.100 (φ1A = 57.42) (L12)
(6) φ1A / fw = 2.915 (φ1A = 54.00) (L13)
(7) ndN = 1.834000 (L11)
(8) νdN = 37.17 (L11)
(9) νd3 = 67.87 (L31)

  2A and 2B are graphs showing various aberrations of the variable magnification optical system according to the first example in the infinite focus state. FIG. 2A is a wide-angle end state, FIG. 2B is an intermediate focal length state, and FIG. Each end state is shown.

  In each aberration diagram, FNO represents an F number, and A represents a half angle of view (unit: “°”). Further, d represents d-line (wavelength 587.6 nm), g represents various aberrations with respect to g-line (wavelength 435.8 nm), and those not described represent various aberrations with respect to d-line. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane.

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

  From each aberration diagram, it is understood that the variable magnification optical system according to the first example has various optical aberrations corrected and high optical performance.

(Second embodiment)
FIG. 3 is a cross-sectional view showing the configuration of the variable magnification optical system according to the second example.

  As shown in FIG. 3, the zoom optical system according to the second example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side along the optical axis. And a third lens group G3 having a positive refractive power. The third lens group G3 includes, in order from the object side along the optical axis, a thirty-first lens group G31 having a positive refractive power and a thirty-second lens group G32 having a positive refractive power.

  When zooming from the wide-angle end state W to the telephoto end state T, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases. Thus, with respect to the image plane I, the first lens group G1 monotonously moves toward the object side, the second lens group G2 moves once toward the image side, then moves toward the object side, and the third lens group G3 Move to the object side monotonously. Further, the 31st lens group G31 and the 32nd lens group G32 move monotonously with respect to the image plane I toward the object side so that the distance between the 31st lens group G31 and the 32nd lens group G32 decreases.

  The aperture stop S is disposed closest to the object side of the third lens group G3 on the image side of the second lens group G2, and is configured integrally with the 31st lens group G31.

  The first lens group G1 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. It is composed of

  The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens having a convex surface directed toward the image side. It consists of a cemented lens of L24 and a positive meniscus lens L25 having a convex surface facing the image side. The negative meniscus lens L21 located closest to the object side in the second lens group G2 is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The thirty-first lens group G31 has, in order from the object side along the optical axis, a convex surface facing the biconvex lens L31, the biconvex lens L32, the cemented lens of the biconvex lens L33 and the biconcave lens L34, and the biconcave lens L35. Further, it is composed of a cemented lens with the positive meniscus lens L36 and a negative meniscus lens L37 having a concave surface facing the object side. The biconcave lens L35 is a glass mold aspheric lens having an aspheric lens surface on the object side.

  The thirty-second lens group G32 includes, in order from the object side along the optical axis, a biconvex lens L41 and a cemented lens of a biconcave lens L42 and a biconvex lens L43. The biconvex lens L41 located closest to the object side in the thirty-second lens group G32 is a glass mold aspheric lens having an aspheric lens surface on the object side. Light rays emitted from the biconvex lens L43 form an image on the image plane I.

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

(Table 2)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 123.95945 2.00000 1.850260 32.35
2 65.81889 9.30000 1.497820 82.52
3 -679.81898 0.10000
4 66.63494 6.20000 1.593190 67.87
5 419.93083 (variable)

6 * 162.32416 0.15000 1.553890 38.09
7 146.07537 1.00000 1.834807 42.72
8 16.13035 6.55000
9 -35.27597 1.00000 1.882997 40.76
10 60.44503 0.10000
11 37.37226 5.20000 1.846660 23.78
12 -32.72792 0.82143
13 -23.94628 1.00000 1.882997 40.76
14 -252.41497 2.00000 1.808090 22.79
15 -72.44788 (variable)

16 (Aperture) ∞ 1.00000
17 36.72216 3.30000 1.593190 67.87
18 -118.19629 0.10000
19 41.37679 3.15000 1.487490 70.41
20 -92.34292 0.10000
21 42.34033 3.80000 1.487490 70.41
22 -41.00357 1.00000 1.805181 25.43
23 259.36092 3.81909
24 * -63.64853 1.00000 1.806100 40.94
25 22.00000 2.90000 1.805181 25.43
26 150.57815 4.20000
27 -45.82441 1.00000 1.882997 40.76
28 -215.98952 (variable)

29 * 77.17936 3.15000 1.589130 61.16
30 -37.11866 0.10000
31 -261.29488 1.00000 1.882997 40.76
32 39.98076 4.40000 1.518229 58.93
33 -48.52092 (Bf)
Image plane ∞

(Aspheric data)
6th surface κ = -5.7774
A4 = 6.79980E-06
A6 = -2.52730E-08
A8 = 8.26150E-11
A10 = -1.02860E-13
24th surface κ = 2.8196
A4 = 4.59750E-06
A6 = 4.28350E-09
A8 = 0.00000E + 00
A10 = 0.00000E + 00
29th surface κ = -6.5363
A4 = -1.95310E-05
A6 = 1.79050E-08
A8 = -1.55070E-10
A10 = 4.13770E-13

(Various data)
Zoom ratio 15.696
W M T
f = 18.53979 104.99746 290.99204
FNO = 4.10702 5.39973 5.39939
ω = 38.99845 7.50128 2.73812
Y = 14.20 14.20 14.20
TL = 160.00885 218.99165 237.79997
Bf = 39.11693 89.39051 99.16649

d5 2.15153 45.02627 65.69297
d15 40.45482 13.14016 2.00000
d28 8.84506 1.99420 1.50000

(Zoom lens group data)
Group Start surface Focal length 1 1 103.25223
2 6-15.13084
3 16 39.55369 (W)
35.07124 (M)
34.78685 (T)
31 16 44.74649
32 29 47.36030

(Values for conditional expressions)
(1) ndA = 1.497820 (L12)
νdA = 82.52 (L12)
(1) ndA = 1.593190 (L13)
νdA = 67.87 (L13)
(2) f1 / fw = 5.569
(3) f1 / ft = 0.355
(4) Δ1 / f1 = 0.553
(5) f1A / f1 = 1.172 (L12)
(5) f1A / f1 = 1.285 (L13)
(6) φ1A / fw = 2.999 (φ1A = 55.60) (L12)
(6) φ1A / fw = 2.918 (φ1A = 54.10) (L13)
(7) ndN = 1.850260 (L11)
(8) νdN = 32.35 (L11)
(9) νd3 = 67.87 (L31)

  FIG. 4 shows various aberration diagrams of the variable magnification optical system according to Example 2 in the infinitely focused state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is telephoto. Each end state is shown.

  From the respective aberration diagrams, it can be seen that the variable magnification optical system according to the second example has various optical aberrations corrected and high optical performance.

(Third embodiment)
FIG. 5 is a cross-sectional view showing the configuration of the variable magnification optical system according to the third example.

  As shown in FIG. 5, the variable magnification optical system according to the third example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side along the optical axis. And a third lens group G3 having a positive refractive power. The third lens group G3 includes, in order from the object side along the optical axis, a 31st lens group G31 having a positive refractive power, a 32nd lens group G32 having a negative refractive power, and a 33rd lens group G33 having a positive refractive power. Composed.

  When zooming from the wide-angle end state W to the telephoto end state T, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases. Thus, with respect to the image plane I, the first lens group G1 monotonously moves toward the object side, the second lens group G2 moves once toward the image side, then moves toward the object side, and the third lens group G3 Move to the object side monotonously. Further, the distance between the 31st lens group G31 and the 32nd lens group G32 is increased, and the distance between the 32nd lens group G32 and the 33rd lens group G33 is decreased, so that the 31st lens group G31 and the 32nd lens group are reduced. G32 and the 33rd lens group G33 move to the object side monotonously with respect to the image plane I.

  The aperture stop S is disposed closest to the object side of the third lens group G3 on the image side of the second lens group G2, and is configured integrally with the 31st lens group G31.

  The first lens group G1 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. It is composed of

  The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, a biconvex lens L23, a biconcave lens L24, and a biconvex lens L25. It consists of a lens. The negative meniscus lens L21 located closest to the object side in the second lens group G2 is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The thirty-first lens group G31 includes, in order from the object side along the optical axis, a biconvex lens L31, a biconvex lens L32, a cemented lens of a biconvex lens L33, and a negative meniscus lens L34 having a concave surface facing the object side. ing.

  The thirty-second lens group G32 includes, in order from the object side along the optical axis, a cemented lens of a biconcave lens L41 and a positive meniscus lens L42 having a convex surface facing the object side, and a negative meniscus lens L43 having a concave surface facing the object side. It is composed of The biconcave lens L41 located closest to the object side in the thirty-second lens group G32 is a compound aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The thirty-third lens group G33 includes, in order from the object side along the optical axis, a biconvex lens L51, a biconvex lens L52, and a cemented lens of a biconcave lens L53 and a biconvex lens L54. The biconvex lens L51 located closest to the object side in the thirty-third lens group G33 is a glass mold aspheric lens having an aspheric lens surface on the object side. Light rays emitted from the biconvex lens L54 form an image on the image plane I.

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

(Table 3)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 175.60560 2.20000 1.834000 37.16
2 67.43020 8.80000 1.497820 82.52
3 -587.78480 0.10000
4 72.27100 6.45000 1.593190 67.87
5 1826.13880 (variable)

6 * 84.76870 0.10000 1.553890 38.09
7 73.93750 1.20000 1.834807 42.72
8 17.18730 6.95000
9 -36.98220 1.00000 1.816000 46.62
10 77.92630 0.15000
11 36.63460 5.30000 1.784723 25.68
12 -36.63460 0.80000
13 -26.19910 1.00000 1.816000 46.62
14 63.73960 2.05000 1.808090 22.79
15 -643.27060 (variable)

16 (Aperture) ∞ 1.00000
17 65.83650 3.40000 1.593190 67.87
18 -50.15460 0.10000
19 65.68170 2.45000 1.487490 70.41
20 -154.97430 0.10000
21 46.73330 4.20000 1.487490 70.41
22 -35.78330 1.00000 1.808090 22.79
23 -191.93180 (variable)

24 * -57.29660 0.20000 1.553890 38.09
25 -59.72500 0.90000 1.696797 55.52
26 28.51000 2.15000 1.728250 28.46
27 91.99760 4.14020
28 -32.89540 1.00000 1.729157 54.66
29 -144.33150 (variable)

30 * 6427.19190 4.65000 1.589130 61.18
31 -27.38180 0.10000
32 31.47760 5.85000 1.487490 70.41
33 -43.75390 1.45000
34 -113.58970 1.00000 1.882997 40.76
35 20.34810 5.30000 1.548141 45.79
36 -709.14530 (Bf)
Image plane ∞

(Aspheric data)
6th surface κ = 1.0000
A4 = 2.88220E-06
A6 = -2.29350E-11
A8 = -2.35280E-11
A10 = 9.21570E-14
24th surface κ = 1.0000
A4 = 4.32780E-06
A6 = 1.88460E-09
A8 = 0.00000E + 00
A10 = 0.00000E + 00
30th surface κ = 1.0000
A4 = -1.36170E-05
A6 = -3.55860E-10
A8 = 1.83080E-11
A10 = -1.86790E-13

(Various data)
Zoom ratio 15.701
W M T
f = 18.56060 104.65150 291.42454
FNO = 3.57565 5.62482 5.81064
ω = 38.80191 7.44205 2.72113
Y = 14.20 14.20 14.20
TL = 164.76435 225.28899 250.61470
Bf = 38.84705 73.57929 86.64770

d5 2.15700 53.01000 76.25220
d15 33.36360 11.30360 2.00000
d23 3.46820 9.64300 9.62460
d29 11.83830 2.66290 1.00000

(Zoom lens group data)
Group Start surface Focal length 1 1 117.7729
2 6 -15.60945
3 16 40.44771 (W)
33.95695 (M)
32.70088 (T)
31 16 27.35473
32 24 -26.50041
33 30 35.423

(Values for conditional expressions)
(1) ndA = 1.497820 (L12)
νdA = 82.52 (L12)
(1) ndA = 1.593190 (L13)
νdA = 67.87 (L13)
(2) f1 / fw = 6.343
(3) f1 / ft = 0.404
(4) Δ1 / f1 = 0.729
(5) f1A / f1 = 1.037 (L12)
(5) f1A / f1 = 1.76 (L13)
(6) φ1A / fw = 3.081 (φ1A = 57.19) (L12)
(6) φ1A / fw = 2.909 (φ1A = 54.00) (L13)
(7) ndN = 1.834000 (L11)
(8) νdN = 37.16 (L11)
(9) νd3 = 67.87 (L31)

  FIG. 6 shows various aberration diagrams of the zoom optical system according to the third example in the infinite focus state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is telephoto. Each end state is shown.

  From each aberration diagram, it can be seen that the variable magnification optical system according to the third example has various optical aberrations corrected and high optical performance.

(Fourth embodiment)
FIG. 7 is a cross-sectional view showing a configuration of a variable magnification optical system according to the fourth example.

  As shown in FIG. 7, the variable magnification optical system according to the fourth example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side along the optical axis. And a third lens group G3 having a positive refractive power. The third lens group G3 includes, in order from the object side along the optical axis, a thirty-first lens group G31 having a positive refractive power and a thirty-second lens group G32 having a positive refractive power.

  When zooming from the wide-angle end state W to the telephoto end state T, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases. Thus, with respect to the image plane I, the first lens group G1 monotonously moves toward the object side, the second lens group G2 moves once toward the image side, then moves toward the object side, and the third lens group G3 Move to the object side monotonously. Further, the 31st lens group G31 and the 32nd lens group G32 move monotonously with respect to the image plane I toward the object side so that the distance between the 31st lens group G31 and the 32nd lens group G32 decreases.

  The aperture stop S is disposed closest to the object side of the third lens group G3 on the image side of the second lens group G2, and is configured integrally with the 31st lens group G31.

  The first lens group G1 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. It is composed of

  The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens having a convex surface directed toward the image side. It consists of a cemented lens of L24 and a positive meniscus lens L25 having a convex surface facing the image side. The negative meniscus lens L21 located closest to the object side in the second lens group G2 is a composite aspherical lens in which an aspherical surface is formed by providing a resin layer on the object-side lens surface.

  The thirty-first lens group G31 includes, in order from the object side along the optical axis, a biconvex lens L31, a biconvex lens L32, a cemented lens composed of a biconvex lens L33 and a biconcave lens L34, and a cemented biconvex lens L35 and a biconvex lens L36. The lens includes a negative meniscus lens L37 having a concave surface facing the object side. The biconcave lens L35 is a glass mold aspheric lens having an aspheric lens surface on the object side.

  The thirty-second lens group G32 includes, in order from the object side along the optical axis, a biconvex lens L41, and a cemented lens of a negative meniscus lens L42 having a convex surface facing the object side and a biconvex lens L43. The biconvex lens L41 located closest to the object side in the thirty-second lens group G32 is a glass mold aspheric lens having an aspheric lens surface on the object side. Light rays emitted from the biconvex lens L43 form an image on the image plane I.

  Table 4 below lists various values of the variable magnification optical system according to the fourth example.

(Table 4)

(Surface data)
Surface number rd nd νd
Object ∞ ∞
1 127.94447 2.00000 1.850260 32.35
2 66.54596 7.85000 1.497820 82.52
3 -596.23069 0.10000
4 67.44029 5.40000 1.593190 67.87
5 436.18989 (variable)

6 * 135.29609 0.15000 1.553890 38.09
7 107.25966 1.00000 1.804000 46.58
8 15.26261 6.70000
9 -34.54986 1.00000 1.834807 42.72
10 51.89897 0.10000
11 34.09670 4.50000 1.784723 25.68
12 -32.12451 0.90000
13 -21.11569 1.00000 1.882997 40.76
14 -2390.20620 2.10000 1.922860 20.50
15 -67.61249 (variable)

16 (Aperture) ∞ 1.00000
17 31.61335 3.65000 1.593190 67.87
18 -218.55454 0.10000
19 49.13044 3.20000 1.487490 70.41
20 -63.62105 0.10000
21 35.35729 4.25000 1.487490 70.41
22 -34.07826 1.00000 1.846660 23.78
23 659.96058 3.90000
24 * -35.03665 1.00000 1.756998 47.82
25 17.58221 3.90000 1.698947 30.13
26 -95.26227 3.35000
27 -55.52002 1.00000 1.882997 40.76
28 -585.51718 (variable)

29 * 439.79346 2.20000 1.589130 61.16
30 -53.20688 0.10000
31 65.13402 1.00000 1.834000 37.16
32 27.72956 4.10000 1.487490 70.41
33 -58.13289 (Bf)
Image plane ∞

(Aspheric data)
6th surface κ = 4.3350
A4 = 9.45630E-06
A6 = -1.51470E-08
A8 = -1.16860E-12
A10 = 1.65790E-13
24th surface κ = -0.3009
A4 = 6.23810E-06
A6 = 8.96820E-09
A8 = 0.00000E + 00
A10 = 0.00000E + 00
29th surface κ = -20.0000
A4 = -1.92960E-05
A6 = 5.96200E-09
A8 = -1.65600E-10
A10 = 4.18100E-13

(Various data)
Zoom ratio 15.698
W M T
f = 18.53928 105.00169 291.02949
FNO = 3.60631 5.76130 5.78825
ω = 39.00856 7.48510 2.73699
Y = 14.20 14.20 14.20
TL = 148.79923 217.34659 242.82932
Bf = 39.00067 91.11965 105.34665

d5 2.10000 46.65937 67.33267
d15 33.50310 10.98454 2.00000
d28 7.54546 1.93303 1.50000

(Zoom lens group data)
Group Start surface Focal length 1 1 104.3654
2 6-13.81152
3 16 36.1068 (W)
32.66171 (M)
32.4030 (T)
31 16 39.54020
32 29 48.03635

(Values for conditional expressions)
(1) ndA = 1.497820 (L12)
νdA = 82.52 (L12)
(1) ndA = 1.593190 (L13)
νdA = 67.87 (L13)
(2) f1 / fw = 5.626
(3) f1 / ft = 0.358
(4) Δ1 / f1 = 0.901
(5) f1A / f1 = 1.157 (L12)
(5) f1A / f1 = 1.282 (L13)
(6) φ1A / fw = 2.982 (φ1A = 55.29) (L12)
(6) φ1A / fw = 2.919 (φ1A = 54.12) (L13)
(7) ndN = 1.850260 (L11)
(8) νdN = 32.35 (L11)
(9) νd3 = 67.87 (L31)

  FIGS. 8A and 8B are graphs showing various aberrations of the zoom optical system according to Example 4 in the infinitely focused state, where FIG. 8A is a wide angle end state, FIG. 8B is an intermediate focal length state, and FIG. 8C is telephoto. Each end state is shown.

  From the respective aberration diagrams, it can be seen that the variable magnification optical system according to the fourth example has various aberrations corrected well and high optical performance.

  As described above, according to the present embodiment, it is possible to provide a variable magnification optical system that suppresses aberration fluctuation and has high optical performance.

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

  FIG. 9 is a diagram illustrating a configuration of a camera including the variable magnification optical system according to the first example.

  In FIG. 9, a camera 1 is a digital single-lens reflex camera provided with a variable magnification optical system according to the first example as a photographing lens 2. In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and is focused on the focusing screen 4 via the quick return mirror 3. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image through the eyepiece 6.

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

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

  Even if the camera does not have the quick return mirror 3, the same effect as the camera 1 can be obtained.

  The outline of the manufacturing method of the variable magnification optical system of the present application will be described below.

  FIG. 10 is a diagram showing a manufacturing method of the variable magnification optical system of the present application.

  The variable magnification optical system manufacturing method of the present application includes, in order from the object side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. Is a method for manufacturing a variable magnification optical system having steps S1, S2, and S3 shown in FIG.

  Step S1: When changing the magnification of the first lens group, the second lens group, and the third lens group from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group can be increased. The distance between the second lens group and the third lens group is arranged so as to be reduced.

  Step S2: A plurality of positive lenses satisfying the following conditional expression (1) are arranged in the first lens group.

Step S3: The following conditional expressions (2) and (3) are satisfied.
(1) When ndA ≧ 1.540 νdA> 66.5
When ndA <1.540 νdA> 75.0
(2) 4.75 <f1 / fw <11.00
(3) 0.28 <f1 / ft <0.52
Where ndA is the refractive index of the materials of the plurality of positive lenses in the first lens group with respect to the d-line, νdA is the Abbe number of the materials of the plurality of positive lenses in the first lens group with respect to the d-line, and fw is in the wide-angle end state. The focal length of the entire variable magnification optical system, ft is the focal length of the entire variable magnification optical system in the telephoto end state, and f1 is the focal length of the first lens group.

  According to the manufacturing method of the variable magnification optical system of the present application, it is possible to manufacture a variable magnification optical system that suppresses aberration fluctuation and has high optical performance.

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

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

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

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

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

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

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

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

  The variable magnification optical system of the present embodiment has a variable magnification ratio of about 7 to 25.

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

  In the variable power optical system of the present embodiment, it is preferable that the second lens group has one positive lens component and three negative lens components. In the second lens group, it is preferable that the lens components are arranged in order of negative, positive and negative in order from the object side with an air gap interposed therebetween.

  In the variable magnification optical system of the present embodiment, it is preferable that the third lens group has at least three positive lens components and at least one negative lens component.

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

G1 1st lens group G2 2nd lens group G3 3rd lens group G31 31st lens group G32 32nd lens group G33 33rd lens group L11 Negative meniscus lens L12 Biconvex lens L13 Positive meniscus lens L31 Biconvex lens S Aperture stop I Image surface 1 Camera

Claims (13)

In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
The plurality of positive lenses in the first lens group is two,
A zoom optical system characterized by satisfying the following conditional expression:
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.48
However,
ndA: Refractive index νdA for the material of the plurality of positive lenses in the first lens group νdA: Abbe number fw for the material of the plurality of positive lenses in the first lens group fw: in the wide-angle end state Focal length ft of the entire zooming optical system: focal length f1 of the entire zooming optical system in the telephoto end state f1: Focal length of the first lens group In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
The plurality of positive lenses in the first lens group is two,
A zoom optical system characterized by satisfying the following conditional expression:
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.52
0.65 <f1A / f1 <1.75
However,
ndA: Refractive index νdA for the material of the plurality of positive lenses in the first lens group νdA: Abbe number fw for the material of the plurality of positive lenses in the first lens group fw: in the wide-angle end state Focal length ft of the entire variable magnification optical system: Focal length f1 of the entire variable magnification optical system in the telephoto end state f1: Focal length f1A of the first lens group: Focal points of the plurality of positive lenses in the first lens group distance In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
A zoom optical system characterized by satisfying the following conditional expression:
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.48
0.25 <Δ1 / f1 <1.10
However,
ndA: Refractive index νdA for the material of the plurality of positive lenses in the first lens group νdA: Abbe number fw for the material of the plurality of positive lenses in the first lens group fw: in the wide-angle end state Focal length ft of the entire zooming optical system: focal length f1 of the entire zooming optical system in the telephoto end state f1: focal length Δ1: the first lens group on the image plane from the wide-angle end state to the telephoto end state Movement amount of one lens group In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
A zoom optical system characterized by satisfying the following conditional expression:
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.52
0.25 <Δ1 / f1 <1.10
0.65 <f1A / f1 <1.75
However,
ndA: Refractive index νdA for the material of the plurality of positive lenses in the first lens group νdA: Abbe number fw for the material of the plurality of positive lenses in the first lens group fw: in the wide-angle end state Focal length ft of the entire zooming optical system: focal length f1 of the entire zooming optical system in the telephoto end state f1: focal length Δ1: the first lens group on the image plane from the wide-angle end state to the telephoto end state Movement amount f1A of one lens group: focal lengths of the plurality of positive lenses in the first lens group In order from the object side along the optical axis, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power,
The third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power and a 32nd lens group having a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the entire optical system in which the distance between the thirty-first lens group and the thirty-second lens group decreases substantially consists of four lens groups,
Alternatively, the third lens group includes, in order from the object side along the optical axis, a 31st lens group having a positive refractive power, a 32nd lens group having a negative refractive power, and a 33rd lens group having a positive refractive power,
An optical system in which the distance between the thirty-first lens group and the thirty-second lens group changes and the distance between the thirty-second lens group and the thirty-third lens group changes upon zooming from the wide-angle end state to the telephoto end state. It consists essentially of 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases.
The first lens group has a plurality of positive lenses that satisfy the following conditional expression:
A zoom optical system characterized by satisfying the following conditional expression:
When ndA ≧ 1.540, νdA> 66.5
When ndA <1.540 νdA> 75.0
5.569 ≦ f1 / fw <11.00
0.28 <f1 / ft <0.44
However,
ndA: Refractive index νdA for the material of the plurality of positive lenses in the first lens group νdA: Abbe number fw for the material of the plurality of positive lenses in the first lens group fw: in the wide-angle end state Focal length ft of the entire zooming optical system: focal length f1 of the entire zooming optical system in the telephoto end state f1: Focal length of the first lens group The zoom lens system according to claim 1 or 2, wherein the following conditional expression is satisfied.
0.25 <Δ1 / f1 <1.10
However,
Δ1: Amount of movement of the first lens group with respect to the image plane from the wide-angle end state to the telephoto end state 6. The variable magnification optical system according to claim 5, wherein the following conditional expression is satisfied.
0.65 <f1A / f1 <1.75
However,
f1A: focal lengths of the plurality of positive lenses in the first lens group The zoom lens system according to claim 1, wherein the following conditional expression is satisfied.
1.75 <φ1A / fw <4.50
However,
φ1A: Effective diameter of the plurality of positive lenses in the first lens group 9. The variable magnification optical system according to claim 1, wherein the first lens group includes a negative lens that satisfies the following conditional expression. 10.
1.750 <ndN
28.0 <νdN <50.0
However,
ndN: refractive index νdN of the negative lens material in the first lens group with respect to the d-line νdN: Abbe number of the negative lens material in the first lens group with respect to the d-line   The variable magnification optical system according to claim 9, wherein the number of the negative lenses in the first lens group is one. 11. The variable magnification optical system according to claim 1, wherein the third lens group includes a positive lens that satisfies the following conditional expression. 11.
νd3> 65.5
However,
νd3: Abbe number with respect to d-line of the material of the positive lens in the third lens group   During zooming from the wide-angle end state to the telephoto end state, the distance between the thirty-first lens group and the thirty-second lens group increases, and the distance between the thirty-second lens group and the thirty-third lens group decreases. The variable power optical system according to claim 1, wherein the zoom lens system has a variable magnification.   An optical apparatus comprising the variable magnification optical system according to claim 1.

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