JP5338865B2 - Variable-magnification optical system, optical device, and variable-magnification optical system manufacturing method - 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, 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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
νdA> 85.0
5.10 <f1 / fw <11.00
0.65 <f1A / f1 <1.75
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length of the first lens group
f1A: focal length of the positive lens A 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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
νdA> 85.0
5.10 <f1 / fw <11.00
0.36 <Δ1 / f1 <1.10
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length Δ1 of the first lens group Δ1: wide-angle end The moving amount of the first lens group with respect to the image plane from the state to the telephoto end state.
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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
νdA> 85.0
3.90 <f1 / fw <11.00
0.734 ≦ Δ1 / f1 <1.10
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length Δ1 of the first lens group Δ1: wide-angle end The moving amount of the first lens group with respect to the image plane from the state to the telephoto end state.
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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
It satisfies the following conditional expression,
νdA> 85.0
3.90 <f1 / fw <11.00
0.65 <f1A / f1 <1.75
The third lens group includes a positive lens that satisfies the following conditional expression, and provides a variable magnification optical system.
When nd3 ≧ 1.540, νd3> 65.5
When nd3 <1.540 νd3> 75.0
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length f1 of the entire zooming optical system in the wide-angle end state f1: focal length f1A of the first lens group Focal length nd3 of the positive lens A in one lens group: Refractive index νd3 with respect to the d-line of the material of the positive lens in the third lens group: With respect to the d-line of the material of the positive lens in the third lens group Abbe number

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

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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during zooming from the wide-angle end state to the telephoto end state. A method of manufacturing a variable magnification optical system substantially consisting of five lens groups as a whole,
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,
A positive lens A that satisfies the following conditional expression is disposed in the first lens group,
A variable magnification optical system manufacturing method characterized by satisfying the following conditional expression is provided.
νdA> 85.0
5.10 <f1 / fw <11.00
0.65 <f1A / f1 <1.75
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length of the first lens group
f1A: focal length of the positive lens A in the first lens group

  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 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 positive lens A that satisfies the following conditional expression (1), and satisfies the following conditional expression (2).
(1) νdA> 85.0
(2) 3.90 <f1 / fw <11.00
Where νdA is the Abbe number with respect to the d-line (wavelength λ = 587.6 nm) of the material of the positive lens A in the first lens group, fw is the focal length of the entire variable magnification optical system in the wide-angle end state, and f1 is the first This is the focal length of the lens group.

  Conditional expression (1) defines the optimum Abbe number of the material of the positive lens A in the first lens group, and suppresses chromatic aberration fluctuations that occur during zooming from the wide-angle end state to the telephoto end state, thereby achieving high optical performance. It is a conditional expression for realizing.

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

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

  When the lower limit of conditional expression (2) is not reached, the refractive power of the first lens group becomes strong, and it becomes difficult to suppress the variation of lateral chromatic aberration and off-axis aberration, particularly astigmatism, and 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 weak, so that it is necessary to increase the amount of movement of the first lens group relative to the image plane in order to obtain a predetermined zoom ratio. Come. Then, when the magnification is changed from the wide-angle end state to the telephoto end state, the variation in the height from the optical axis of the off-axis light beam passing through the first lens group becomes large. Therefore, lateral chromatic aberration and off-axis aberration, particularly astigmatism It becomes difficult to suppress fluctuations, 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 (2) to 4.75. In order to further secure the effect of the embodiment, it is more 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.

In addition, it is desirable that the variable magnification optical system according to the present embodiment satisfies the following conditional expression (3).
(3) 0.28 <f1 / ft <0.52
Where ft is the focal length of the entire variable magnification optical system in the telephoto end state.

  Conditional expression (3) defines the optimum focal length range of the first lens group, and realizes high optical performance by suppressing fluctuations in chromatic aberration and off-axis aberration that occur during zooming from the wide-angle end state to the telephoto end state. 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 strong, and it becomes 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 weak, so that it is necessary to increase the amount of movement of the first lens group relative to the image plane in order to obtain a predetermined zoom ratio. Come. Then, when the magnification is changed from the wide-angle end state to the telephoto end state, the variation in the height from the optical axis of the off-axis light beam passing through the first lens group becomes large. Therefore, lateral chromatic aberration and off-axis aberration, particularly astigmatism It becomes difficult to suppress fluctuations, 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 (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 with respect to the image plane from the wide-angle end state to the telephoto end state, and suppresses fluctuations in chromatic aberration and off-axis aberrations that occur during zooming, resulting in high optical performance. Is a conditional expression for realizing

  If the lower limit of conditional expression (4) is not reached, the amount of movement of the first lens group relative to the image plane decreases, 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 state to the telephoto end state, a change in refractive power due to a change in height from the optical axis of the off-axis light beam passing through the first lens group increases, so that lateral chromatic aberration and off-axis aberration, In particular, it becomes difficult to suppress fluctuations in astigmatism, and high optical performance cannot be realized.

  When the upper limit value of conditional expression (4) is exceeded, the amount of movement of the first lens group relative to the image plane increases, and the off-axis light flux passing through the first lens group during zooming from the wide-angle end state to the telephoto end state is increased. Since the variation in height from the optical axis becomes large, it becomes difficult to suppress the variation 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 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 the positive lens A in the first lens group.

  Conditional expression (5) defines the optimum focal length of the positive lens A in the first lens group, and is a conditional expression for realizing high optical performance by suppressing variations in chromatic aberration and off-axis aberration that occur during zooming. It is.

  When the lower limit value of conditional expression (5) is not reached, the refractive power of the positive lens A becomes strong. Therefore, when zooming from the wide-angle end state to the telephoto end state, the off-axis light beam passing through the positive lens A from the optical axis The change in refractive power accompanying the change in height becomes large, and it becomes difficult to suppress the change in lateral chromatic aberration and off-axis aberration, particularly astigmatism, and high optical performance cannot be realized.

  When the upper limit of conditional expression (5) is exceeded, the refractive power of the positive lens A becomes weak and the refractive power of positive lenses other than the positive lens A in the first lens group becomes strong. When changing to the state, the refractive power change due to the change in the height of the off-axis light beam passing through the positive lens A from the optical axis increases, and the change in lateral chromatic aberration and off-axis aberration, particularly astigmatism, can be suppressed. It becomes difficult 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 the effective diameter of the positive lens A in the first lens group.

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

  When the lower limit value of conditional expression (6) is not reached, there is little fluctuation in the height from the optical axis of the off-axis light beam passing through the positive lens A in the first lens group when zooming from the wide-angle end state to the telephoto end state. Therefore, it becomes difficult to suppress fluctuations in off-axis aberrations, particularly astigmatism, and high optical performance cannot be realized.

  When the upper limit value of conditional expression (6) is exceeded, the variation in height from the optical axis of the off-axis light beam passing through the positive lens A in the first lens group is large when zooming from the wide-angle end state to the telephoto end state. Therefore, 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 magnification optical system according to the present embodiment, it is desirable that the first lens group has a positive lens B that satisfies the following conditional expression (7).
(7) ndB> 1.580
Here, ndB is the refractive index with respect to the d-line (wavelength λ = 587.6 nm) of the material of the positive lens B in the first lens group.

  Conditional expression (7) defines the optimum refractive index of the material of the positive lens B in the first lens group, and is a conditional expression for realizing high optical performance by suppressing fluctuations in off-axis aberrations that occur during zooming. It is.

  If the lower limit value of conditional expression (7) is not reached, the curvature of the surface of the positive lens B becomes large. Therefore, when zooming from the wide-angle end state to the telephoto end state, from the optical axis of the off-axis light beam passing through the positive lens B The change in the declination accompanying the fluctuation in height becomes large, and it becomes difficult to suppress fluctuations in off-axis aberrations, particularly astigmatism, and high optical performance cannot be realized.

In the variable magnification optical system according to the present embodiment, it is desirable that the first lens group has a positive lens B that satisfies the following conditional expression (8).
(8) 40.0 <νdB <66.5
Where νdB is the Abbe number with respect to the d-line (wavelength λ = 587.6 nm) of the material of the positive lens B in the first lens group.

  Conditional expression (8) defines the optimal Abbe number of the material of the positive lens B in the first lens group, and is a conditional expression for realizing high optical performance by suppressing variation in chromatic aberration that occurs during zooming. .

  When the lower limit value of conditional expression (8) is not reached, the dispersion of the material of the positive lens B becomes large. Therefore, when zooming from the wide-angle end state to the telephoto end state, the optical axis of the off-axis light beam passing through the positive lens B The variation of the dispersion accompanying the fluctuation of the height of the lens becomes large, and it becomes difficult to suppress the variation of the chromatic aberration of magnification, and high optical performance cannot be realized.

  If the upper limit value of conditional expression (8) is exceeded, the dispersion of the material of the positive lens B becomes small. Therefore, if there is a negative lens in the first lens group, the chromatic aberration correction becomes excessive and the lateral chromatic aberration variation is suppressed. It becomes difficult. Further, when there is no negative lens, chromatic aberration remains and it is difficult to suppress chromatic aberration fluctuation. Therefore, in any case, 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 (8) to 49.0.

In addition, it is desirable that the variable magnification optical system according to the present embodiment satisfies the following conditional expression (9).
(9) 0.65 <f1B / f1 <1.75
Here, f1B is the focal length of the positive lens B in the first lens group.

  Conditional expression (9) defines the optimum focal length of the positive lens B in the first lens group, and is a conditional expression for realizing high optical performance by suppressing variations in chromatic aberration and off-axis aberration that occur during zooming. It is.

  When the lower limit value of conditional expression (9) is not reached, the refractive power of the positive lens B becomes strong. Therefore, when zooming from the wide-angle end state to the telephoto end state, the off-axis light beam passing through the positive lens B from the optical axis The change in refractive power accompanying the change in height becomes large, and it becomes difficult to suppress the change in lateral chromatic aberration and off-axis aberration, particularly astigmatism, and high optical performance cannot be realized.

  When the upper limit of conditional expression (9) is exceeded, the refractive power of the positive lens B becomes relatively weak, and the refractive power of positive lenses other than the positive lens B in the first lens becomes strong. During zooming to the telephoto end state, the change in refractive power accompanying the change in height from the optical axis of the off-axis light beam passing through the positive lens B becomes large, and the change in lateral chromatic aberration and off-axis aberration, particularly astigmatism, is suppressed. It is difficult to achieve high optical performance.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.77.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (9) to 1.42.

In addition, it is desirable that the variable magnification optical system according to the present embodiment satisfies the following conditional expression (10).
(10) 1.75 <φ1B / fw <4.50
However, φ1B is the effective diameter of the positive lens B in the first lens group.

  Conditional expression (10) defines the optimum effective diameter of the positive lens B in the first lens group, and is a conditional expression for realizing high optical performance by suppressing variations in chromatic aberration and off-axis aberration that occur during zooming. It is.

  When the lower limit value of conditional expression (10) is not reached, there is little fluctuation in the height from the optical axis of the off-axis light beam passing through the positive lens B in the first lens group upon zooming from the wide-angle end state to the telephoto end state. Therefore, it becomes difficult to suppress fluctuations in off-axis aberrations, particularly astigmatism, and high optical performance cannot be realized.

  When the upper limit of conditional expression (10) is exceeded, the variation in height from the optical axis of the off-axis light beam passing through the positive lens B in the first lens group is large when zooming from the wide-angle end state to the telephoto end state. Therefore, 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 (10) to 2.45.

  In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (10) to 3.80.

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 (11) and (12).
(11) 1.750 <ndN
(12) 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 (11) defines the optimum refractive index range of the negative lens in the first lens group, and suppresses fluctuations in off-axis aberrations that occur during zooming from the wide-angle end state to the telephoto end state, and has high optical performance. Is a conditional expression for obtaining

  If the lower limit value of conditional expression (11) is not reached, the curvature of the surface of the negative lens in the first lens group becomes large. Therefore, the off-axis light beam that passes through the negative lens upon zooming from the wide-angle end state to the telephoto end state. It is 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 (11) to 1.780.

  Conditional expression (12) defines the optimum Abbe number of the material of the negative lens in the first lens group, and achieves high optical performance by suppressing chromatic aberration fluctuations that occur during zooming from the wide-angle end state to the telephoto end state. This is a conditional expression.

  If the lower limit of conditional expression (12) is not reached, it will be difficult to suppress fluctuations in secondary chromatic aberration during zooming from the wide-angle end state to the telephoto end state, and high optical performance cannot be realized.

  If the upper limit of conditional expression (12) is exceeded, if the predetermined achromaticity is performed in the first lens group, the refractive power of each positive and negative lens increases, and the negative power is changed during zooming from the wide-angle end state to the telephoto end state. It is difficult to suppress off-axis aberrations, particularly astigmatism fluctuations due to fluctuations in the height of the off-axis light beam passing through the lens 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 upper limit of conditional expression (12) to 43.0.

  In the variable magnification optical system according to the present embodiment, it is desirable that the first lens group is composed of one negative lens and two positive lenses.

  With this configuration, it is possible to suppress the thickness of the first lens group, and the off-axis light flux passing through the most object-side surface of the first lens group upon zooming from the wide-angle end state to the telephoto end state. It becomes possible to suppress the fluctuation of the height from the optical axis, it is possible to suppress the fluctuation of off-axis aberration, particularly astigmatism, and realize high optical performance.

In the zoom optical system according to this embodiment, it is desirable that the third lens group has a positive lens that satisfies the following conditional expression (13).
(13) When nd3 ≧ 1.540 νd3> 65.5
When nd3 <1.540 νd3> 75.0
Where nd3 is the refractive index of the positive lens material in the third lens group with respect to the d-line (wavelength λ = 587.6 nm), and νd3 is the positive lens material in the third lens group d-line (wavelength λ = 58.7. Abbe number for 6 nm).

  Conditional expression (13) defines the optimum Abbe number of the positive lens material in the third lens group, and achieves high optical performance by suppressing chromatic aberration fluctuations that occur during zooming from the wide-angle end state to the telephoto end state. This is a conditional expression.

  When the lower limit of conditional expression (13) is not reached, it is difficult to suppress fluctuations in axial chromatic aberration and lateral chromatic aberration, and it is difficult to suppress fluctuations in secondary chromatic aberration because the material has a small anomalous dispersion. In addition, the amount of axial chromatic aberration and lateral chromatic aberration in the visible light region is particularly large in the telephoto end state, and high optical performance cannot be realized.

  In order to secure the effect of the embodiment, when nd3 ≧ 1.540, it is preferable to set the lower limit of conditional expression (13) to 67.5. In order to secure the effect of the embodiment, when nd3 <1.540, it is preferable to set the lower limit of conditional expression (13) to 80.5.

  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 is reduced.

  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 directed toward the object side and a biconvex positive lens L12, and a biconvex positive lens L13. 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 facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave It is composed of a cemented lens of a negative lens L24 having a shape and a positive lens L25 having a biconvex shape. 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 biconvex positive lens L31, a biconvex positive lens L32, a biconvex positive lens L33, and a concave surface facing the object side. It is comprised from the cemented lens with the negative meniscus lens L34.

  The thirty-second lens group G32 includes, in order from the object side along the optical axis, a cemented lens of a biconcave negative lens L41 and a positive meniscus lens L42 having a convex surface on the object side, and a negative lens having a concave surface on the object side. And a meniscus lens L43. The biconcave negative 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.

  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 positive lens L52, a biconcave negative lens L53, and a biconvex shape. The positive lens L54 is a cemented lens. 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. The light beam emitted from the biconvex positive lens L54 forms 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 ∞ ∞
1 205.09180 2.00000 1.882997 40.76
2 67.52420 9.07190 1.456000 91.20
3 -361.42710 0.10000
4 70.10040 6.86700 1.603001 65.46
5 -2470.83790 (variable)

6 * 84.76870 0.15000 1.553890 38.09
7 73.93750 1.20000 1.834807 42.72
8 17.03670 6.46970
9 -49.48220 1.00000 1.816000 46.62
10 52.14060 0.15000
11 31.61490 5.45080 1.761820 26.56
12 -44.44820 1.19350
13 -25.13580 1.00000 1.816000 46.62
14 64.50360 2.42190 1.808090 22.79
15 -166.54310 (variable)

16 (Aperture) ∞ 1.00000
17 63.10220 3.49130 1.593190 67.87
18 -50.22150 0.10000
19 58.68260 2.72200 1.487490 70.41
20 -121.43450 0.10000
21 48.64320 4.10420 1.487490 70.41
22 -34.50080 1.00000 1.808090 22.79
23 -205.15990 (variable)

24 * -66.96860 1.00000 1.693501 53.20
25 26.57120 2.15810 1.761820 26.56
26 63.33840 4.78730
27 -24.70410 1.00000 1.729157 54.66
28 -74.86360 (variable)

29 * -569.79420 3.96090 1.589130 61.16
30 -23.53500 0.10000
31 37.14850 5.00600 1.487490 70.41
32 -45.19690 1.71640
33 -107.03630 1.00000 1.882997 40.76
34 23.36210 4.50160 1.548141 45.79
35 -637.55850 (Bf)
Image plane ∞

(Aspheric data)
6th surface κ = 1.0000
A4 = 3.61880E-06
A6 = -6.10680E-09
A8 = -4.67380E-12
A10 = 5.77660E-14
24th face κ = 1.0000
A4 = 3.81940E-06
A6 = -1.72450E-09
A8 = 0.00000E + 00
A10 = 0.00000E + 00
Surface 29 κ = 1.0000
A4 = -1.63630E-05
A6 = 8.94380E-09
A8 = -2.98150E-11
A10 = 2.87630E-14

(Various data)
Zoom ratio 15.709
W M T
f = 18.56080 104.15546 291.57422
FNO = 3.60018 5.60084 5.87404
ω = 38.95554 7.45367 2.71157
Y = 14.20 14.20 14.20
TL = 163.29692 225.59510 252.97281
Bf = 39.15242 70.61280 82.77641

d5 2.14670 55.86030 80.53690
d15 34.33830 11.46250 2.00000
d23 3.38750 10.66930 11.83690
d28 9.44940 2.16760 1.00000

(Zoom lens group data)
Group Start surface Focal length 1 1 122.10406
2 6-15.86654
3 16 39.50539 (W)
33.18380 (M)
31.88175 (T)
31 16 26.56694
32 24 -24.00147
33 29 33.81791

(Values for conditional expressions)
(1) νdA = 91.20 (L12)
(2) f1 / fw = 6.579
(3) f1 / ft = 0.419
(4) Δ1 / f1 = 0.734
(5) f1A / f1 = 1.029 (L12)
(6) φ1A / fw = 3.007 (φ1A = 55.81) (L12)
(7) ndB = 1.603001 (L13)
(8) νdB = 65.46 (L13)
(9) f1B / f1 = 0.927 (L13)
(10) φ1B / fw = 2.909 (φ1B = 54.00) (L13)
(11) ndN = 1.882297 (L11)
(12) νdN = 40.76 (L11)
(13) nd3 = 1.593190 (L31)
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 to the object side, the second lens group G2 monotonously moves to the object side, and the third lens group G3 monotonously moves to the object side. To do. 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 positive lens L12, and a positive lens having a convex surface facing the object side. And a meniscus lens L13.

  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 facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave And a negative lens L24 having a shape. 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 cemented lens of a biconvex positive lens L31, a biconvex positive lens L32, and a negative meniscus lens L33 having a concave surface facing the object side. And a cemented lens composed of a biconcave negative lens L34 and a positive meniscus lens L35 having a convex surface facing the object side. The biconcave negative lens L34 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-second lens group G32 includes, in order from the object side along the optical axis, a biconvex positive lens L41, a cemented lens of a biconvex positive lens L42 and a biconcave negative lens L43, and a biconvex shape. Positive lens L44. The biconvex positive 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. The light beam emitted from the biconvex positive lens L44 forms 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 ∞ ∞
1 107.02060 1.80000 1.903658 31.31
2 61.29680 9.01320 1.456500 90.27
3 -505.77970 0.10000
4 56.57080 6.56600 1.603001 65.44
5 263.14480 (variable)

6 * 107.66330 0.15000 1.553890 38.09
7 79.43570 1.20000 1.816000 46.62
8 12.54980 5.89610
9 -28.13610 1.00000 1.816000 46.62
10 76.81030 0.10000
11 29.03300 5.08050 1.846660 23.78
12 -28.29410 0.70210
13 -20.32340 1.00000 1.788001 47.37
14 328.32220 (variable)

15 (Aperture) ∞ 0.50000
16 38.51440 4.38040 1.527510 66.72
17 -31.08680 0.10000
18 24.82780 5.70920 1.497000 81.64
19 -22.48490 1.00000 1.850260 32.35
20 -1199.41670 3.00000
21 * -52.55750 0.10000 1.553890 38.09
22 -56.77690 1.00000 1.772499 49.60
23 32.93540 1.94820 1.805181 25.42
24 83.42590 (variable)

25 * 38.17010 5.15170 1.677900 54.89
26 -30.30750 0.10000
27 119.12160 5.79370 1.511790 49.72
28 -16.92620 1.00000 1.878780 41.73
29 40.26250 0.79940
30 88.76870 4.01880 1.497970 53.26
31 -31.87250 (Bf)
Image plane ∞

(Aspheric data)
6th surface κ = 1.0000
A4 = 8.23600E-06
A6 = 2.68070E-08
A8 = -2.85680E-10
A10 = 8.96110E-13
21st surface κ = 1.0000
A4 = 8.39680E-06
A6 = 4.90050E-09
A8 = 0.00000E + 00
A10 = 0.00000E + 00
25th surface κ = 1.0000
A4 = -1.05940E-05
A6 = 2.60370E-08
A8 = 0.00000E + 00
A10 = 0.00000E + 00

(Various data)
Zoom ratio 15.666
W M T
f = 18.57581 134.79308 291.01598
FNO = 3.58467 6.30198 6.35739
ω = 38.75301 5.90773 2.74550
Y = 14.20 14.20 14.20
TL = 141.06118 214.13726 227.18745
Bf = 38.02328 85.33826 92.60805

d5 2.12080 50.67230 62.67010
d14 23.69130 7.80730 1.80000
d24 10.01650 3.11010 2.90000

(Zoom lens group data)
Group Start surface Focal length 1 1 95.68946
2 6 -11.14695
3 15 31.13029 (W)
27.66506 (M)
27.57169 (T)
31 15 42.77504
32 25 40.12768

(Values for conditional expressions)
(1) νdA = 90.27 (L12)
(2) f1 / fw = 5.151
(3) f1 / ft = 0.329
(4) Δ1 / f1 = 0.900
(5) f1A / f1 = 1.258 (L12)
(6) φ1A / fw = 2.998 (φ1A = 55.69) (L12)
(7) ndB = 1.603001 (L13)
(8) νdB = 65.44 (L13)
(9) f1B / f1 = 1.234 (L13)
(10) φ1B / fw = 2.799 (φ1B = 52.00) (L13)
(11) ndN = 1.903658 (L11)
(12) νdN = 31.31 (L11)
(13) nd3 = 1.497000 (L32)
νd3 = 81.64 (L32)

  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 directed toward the object side and a biconvex positive lens L12, and a biconvex positive lens L13. 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 facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave It is composed of a cemented lens of a negative lens L24 having a shape and a positive lens L25 having a biconvex shape. 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 biconvex positive lens L31, a biconvex positive lens L32, a biconvex positive lens L33, and a concave surface facing the object side. It is comprised from the cemented lens with the negative meniscus lens L34.

  The thirty-second lens group G32 includes, in order from the object side along the optical axis, a cemented lens of a biconcave negative lens L41 and a positive meniscus lens L42 having a convex surface on the object side, and a negative lens having a concave surface on the object side. And a meniscus lens L43. The biconcave negative 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.

  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 positive lens L52, a biconcave negative lens L53, and a biconvex shape. The positive lens L54 is a cemented lens. 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. The light beam emitted from the biconvex positive lens L54 forms 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 ∞ ∞
1 193.38060 2.00000 1.883000 40.77
2 66.83560 9.23080 1.437000 95.00
3 -341.14920 0.10000
4 68.78950 6.98760 1.603000 65.47
5 -2649.89320 79.77200 (variable)

6 * 84.76870 0.15000 1.553890 38.09
7 73.93750 1.20000 1.834810 42.72
8 16.94820 6.42970
9 -53.17850 1.00000 1.816000 46.63
10 46.70940 0.15000
11 30.63920 5.37880 1.761820 26.56
12 -48.96880 1.39690
13 -24.42250 1.00000 1.816000 46.63
14 69.10450 2.52380 1.808090 22.79
15 -121.94360 2.00000 (variable)

16 (Aperture) ∞ 1.00000
17 66.08180 3.43590 1.592820 68.69
18 -50.37120 0.10000
19 59.42650 2.78060 1.487490 70.45
20 -108.47870 0.10000
21 49.67940 4.11660 1.487490 70.45
22 -33.83640 1.00000 1.808090 22.79
23 -167.67900 11.82210 (variable)

24 * -64.89240 1.00000 1.693500 53.22
25 27.12400 2.14440 1.761820 26.56
26 65.84410 4.73170
27 -25.14850 1.00000 1.729160 54.66
28 -73.72860 1.00000 (variable)

29 * -448.31420 3.90050 1.589130 61.18
30 -23.64180 0.10000
31 37.43750 4.98090 1.487490 70.45
32 -44.96410 1.73250
33 -102.62990 1.00000 1.883000 40.77

34 23.17730 4.51170 1.548140 45.79
35 -619.02620 (Bf)
Image plane ∞

(Aspheric data)
6th surface κ = 1.0000
A4 = 4.16398E-06
A6 = -7.55222E-09
A8 = -2.91689E-12
A10 = 5.62106E-14
24th surface κ = 1.0000
A4 = 3.83569E-06
A6 = -1.03578E-09
A8 = 0.00000E + 00
A10 = 0.00000E + 00
29th surface κ = 1.0000
A4 = -1.60868E-05
A6 = 8.16360E-09
A8 = -3.55020E-11
A10 = 7.60058E-14

(Various data)
Zoom ratio 15.714
W M T
f = 18.55566 103.95947 291.57591
FNO = 3.63338 5.62730 5.88308
ω = 38.94112 7.46798 2.71133
Y = 14.20 14.20 14.20
TL = 163.38092 225.17861 252.25324
Bf = 39.17162 70.49651 82.47674

d5 2.12700 55.32280 79.77200
d15 34.07780 11.35470 2.00000
d23 3.36200 10.67670 11.82210
d28 9.46010 2.14550 1.00000

(Zoom lens group data)
Group Start surface Focal length 1 1 120.78785
2 6-15.59572
3 16 39.1629 (W)
32.72813 (M)
31.47773 (T)
31 16 26.38558
32 24 -24.49396
33 29 34.76717

(Values for conditional expressions)
(1) νdA = 95.00 (L12)
(2) f1 / fw = 6.509
(3) f1 / ft = 0.414
(4) Δ1 / f1 = 0.636
(5) f1A / f1 = 1.066 (L12)
(6) φ1A / fw = 3.043 (φ1A = 56.47) (L12)
(7) ndB = 1.603000 (L13)
(8) νdB = 65.47 (L13)
(9) f1B / f1 = 0.922 (L13)
(10) φ1B / fw = 2.910 (φ1B = 54.00) (L13)
(11) ndN = 1.883000 (L11)
(12) νdN = 40.77 (L11)
(13) nd3 = 1.59820 (L31)
νd3 = 68.69 (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.

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

  In FIG. 7, 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 a mirrorless camera that does not have the quick return mirror 3 can provide the same effects as the camera 1.

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

  FIG. 8 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 of 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 positive lens A that satisfies the following conditional expression (1) is placed in the first lens group.
(1) νdA> 85.0

Step S3: The following conditional expression (2) is satisfied.
(2) 3.90 <f1 / fw <11.00
Where νdA is the Abbe number of the material of the positive lens A in the first lens group with respect to the d-line, fw is the focal length of the entire variable magnification optical system in the wide-angle 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 errors in processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance.

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

  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 power optical system of the present embodiment, it is preferable that the third lens group has 6 or 7 positive lens components and 3 or 4 negative lens components.

  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 Biconvex lens L31 Biconvex lens S Aperture stop I Image surface 1 camera

Claims (18)

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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
A zoom optical system characterized by satisfying the following conditional expression:
νdA> 85.0
5.10 <f1 / fw <11.00
0.65 <f1A / f1 <1.75
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length of the first lens group
f1A: focal length of the positive lens A 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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
A zoom optical system characterized by satisfying the following conditional expression:
νdA> 85.0
5.10 <f1 / fw <11.00
0.36 <Δ1 / f1 <1.10
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length Δ1 of the first lens group Δ1: wide-angle end The amount of movement of the first lens group with respect to the image plane from the state to the telephoto end state 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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
A zoom optical system characterized by satisfying the following conditional expression:
νdA> 85.0
3.90 <f1 / fw <11.00
0.734 ≦ Δ1 / f1 <1.10
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length Δ1 of the first lens group Δ1: wide-angle end The amount of movement of the first lens group with respect to the image plane from the state to the telephoto end state 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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during 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 includes a positive lens A that satisfies the following conditional expression:
It satisfies the following conditional expression,
νdA> 85.0
3.90 <f1 / fw <11.00
0.65 <f1A / f1 <1.75
The third lens group includes a positive lens that satisfies the following conditional expression:
When nd3 ≧ 1.540, νd3> 65.5
When nd3 <1.540 νd3> 75.0
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length f1 of the entire zooming optical system in the wide-angle end state f1: focal length f1A of the first lens group Focal length nd3 of the positive lens A in one lens group: Refractive index νd3 with respect to the d-line of the material of the positive lens in the third lens group: With respect to the d-line of the material of the positive lens in the third lens group Abbe number The zoom lens system according to claim 1 or 4, 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 The zoom lens system according to claim 3, wherein the following conditional expression is satisfied.
0.65 <f1A / f1 <1.75
However,
f1A: focal length of the positive lens A in the first lens group 4. The variable magnification optical system according to claim 1, wherein the third lens group includes a positive lens that satisfies the following conditional expression. 5.
When nd3 ≧ 1.540, νd3> 65.5
When nd3 <1.540 νd3> 75.0
However,
nd3: Refractive index νd3 for the d-line of the positive lens material in the third lens group: Abbe number for the d-line of the positive lens material in the third lens group The third lens group includes, in order from the object side along the optical axis, the 31st lens group having the positive refractive power, the 32nd lens group having the negative refractive power, and the 33rd lens group having the positive refractive power. ,
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 is a variable magnification optical system. The zoom lens system according to claim 1, wherein the following conditional expression is satisfied.
0.28 <f1 / ft <0.52
However,
ft: focal length of the entire zoom optical system in the telephoto end state The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied.
1.75 <φ1A / fw <4.50
However,
φ1A: effective diameter of the positive lens A in the first lens group 11. The variable magnification optical system according to claim 1, wherein the first lens group includes a positive lens B that satisfies the following conditional expression. 11.
ndB> 1.580
However,
ndB: refractive index of the material of the positive lens B in the first lens group with respect to the d-line 12. The variable magnification optical system according to claim 1, wherein the first lens group includes a positive lens B that satisfies the following conditional expression. 12.
40.0 <νdB <66.5
However,
νdB: Abbe number of the material of the positive lens B in the first lens group with respect to the d-line The zoom lens system according to claim 11 or 12, wherein the following conditional expression is satisfied.
0.65 <f1B / f1 <1.75
However,
f1B: focal length of the positive lens B in the first lens group The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
1.75 <φ1B / fw <4.50
However,
φ1B: Effective diameter of the positive lens B in the first lens group 15. The variable magnification optical system according to claim 1, wherein the first lens group includes a negative lens that satisfies the following conditional expression.
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 power optical system according to any one of claims 1 to 15, wherein the first lens group includes one negative lens and two positive lenses.   An optical apparatus comprising the variable magnification optical system according to claim 1. 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,
Upon 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 decreases substantially consisting of four lens groups as a whole,
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 during zooming from the wide-angle end state to the telephoto end state. A method of manufacturing a variable magnification optical system substantially consisting of five lens groups as a whole,
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,
A positive lens A that satisfies the following conditional expression is disposed in the first lens group,
A variable magnification optical system manufacturing method characterized by satisfying the following conditional expression:
νdA> 85.0
5.10 <f1 / fw <11.00
0.65 <f1A / f1 <1.75
However,
νdA: Abbe number fw of the material of the positive lens A in the first lens group with respect to the d-line fw: focal length of the entire variable magnification optical system in the wide-angle end state f1: focal length of the first lens group
f1A: focal length of the positive lens A in the first lens group

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