JP6331286B2 - Photography lens and optical device - Google Patents

Description

The present invention relates to a photographic lens and an optical apparatus including the photographic lens.

  Conventionally, a so-called retrofocus type wide-angle lens preceding a negative lens is known as a photographic lens (see, for example, Patent Document 1).

JP 2001-228391 A

  However, there is a need for an optical system that has smaller aberration fluctuations during focusing than conventional wide-angle lenses.

SUMMARY OF THE INVENTION An object of the present invention is to provide a photographing lens and an optical apparatus that have a small aberration fluctuation at the time of focusing while being an optical system preceding a negative lens.

In order to solve the above problems, in the present invention,
A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power , substantially 3 in order from the object side along the optical axis. Consisting of a group of lenses
The first lens group includes, in order from the object side, a first lens component having negative refractive power and a second lens component having negative refractive power,
During focusing, the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group moves along the optical axis,
The lens component is a single lens or a cemented lens,
A photographic lens characterized by satisfying the following conditional expression is provided.
7.00 <(− f11) / f <25.00
4.10 <f2 / (-f1) <10.00
However,
f: focal length of the entire photographing lens system at the time of focusing on infinity f1: focal length of the first lens group f11: focal length of the first lens component f2: focal length of the second lens group
The present invention also provides:
A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, substantially 3 in order from the object side along the optical axis. Consisting of a group of lenses
The first lens group includes, in order from the object side, a first lens component having negative refractive power and a second lens component having negative refractive power,
During focusing, the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group moves along the optical axis,
The lens component is a single lens or a cemented lens,
A photographic lens characterized by satisfying the following conditional expression is provided.
6.20 <(− f11) / f <25.00
5.06 ≦ f2 / (− f1) <10.00
However,
f: Focal length of the entire photographing lens system when focusing on infinity
f1: focal length of the first lens group
f11: focal length of the first lens component
f2: focal length of the second lens group

  An optical apparatus according to the present invention includes the above-described photographing lens.

ADVANTAGE OF THE INVENTION According to this invention, although it is an optical system preceding a negative lens, the imaging lens with little aberration fluctuation | variation at the time of focusing and an optical apparatus can be provided.

It is sectional drawing which shows the lens structure of the imaging lens which concerns on 1st Example of this application. FIG. 6 is a diagram illustrating various aberrations of the photographing lens according to the first example of the present application in an infinite focus state. It is sectional drawing which shows the lens structure of the photographic lens which concerns on 2nd Example of this application. FIG. 6 is a diagram illustrating various aberrations of the taking lens according to Example 2 of the present application in an infinitely focused state. It is sectional drawing which shows the lens structure of the photographic lens which concerns on 3rd Example of this application. FIG. 12 is a diagram illustrating various aberrations of the photographing lens according to the third example of the present application in an infinitely focused state. It is sectional drawing which shows the lens structure of the photographic lens which concerns on 4th Example of this application. It is various aberrational figures in the infinite point focusing state of the imaging lens which concerns on 4th Example of this application. It is sectional drawing which shows the lens structure of the photographic lens which concerns on 5th Example of this application. FIG. 10 is a diagram illustrating various aberrations of the taking lens according to Example 5 of the present application in an infinitely focused state. It is sectional drawing of the camera carrying the imaging lens of this application. It is a flowchart which shows the outline of the manufacturing method of the imaging lens of this application.

  Hereinafter, the photographing lens, the optical apparatus, and the manufacturing method of the photographing lens of the present application will be described.

  The photographing lens of the present application includes, in order from the object side along the optical axis, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. The first lens group includes, in order from the object side, a first lens component having a negative refractive power and a second lens component having a negative refractive power. With this configuration, it is possible to perform excellent aberration correction centering on off-axis aberration. In the present application, the lens component refers to a single lens or a cemented lens formed by cementing two or more lenses.

  In focusing, the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group moves along the optical axis. In a wide-angle lens, if a so-called entire extension system that extends the entire lens is adopted, the curvature of field significantly changes to the plus side when focusing from an object at infinity to an object at a short distance. For this reason, the photographic lens of the present application has an inner focus method in which the interval of a part of the lens system is changed to be narrowed in order to reduce the fluctuation of the field curvature when focusing from an object at infinity to an object at a short distance. Adopted. In addition, by adopting a configuration in which focusing is performed only by the second lens group capable of reducing the aperture, the focusing weight (the weight of the lens driven at the time of focusing) is reduced, so that more rapid focusing is performed. It becomes possible.

Moreover, it is preferable that the photographic lens of the present application satisfies the following conditional expression (1), where f is the focal length of the entire system when focusing on infinity and f11 is the focal length of the first lens component.
(1) 6.20 <(− f11) / f <25.00

  Conditional expression (1) is a relational expression between the focal length of the entire system at the time of focusing on infinity and the focal length of the first lens component, and is a conditional expression for realizing an optimum refractive power arrangement of the entire photographing lens. is there.

  If the lower limit value of conditional expression (1) is not reached, the refractive power of the first lens component becomes relatively large with respect to the focal length of the entire system, so that the correction of field curvature and coma aberration becomes excessive. In particular, it is not preferable because sagittal coma aberration and field curvature are deteriorated. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 6.50. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (1) to 7.00.

  If the upper limit value of conditional expression (1) is exceeded, the refractive power of the first lens component becomes relatively small with respect to the focal length of the entire system, so that correction of field curvature and coma aberration is insufficient. Particularly, sagittal coma aberration is deteriorated, which is not preferable. In addition, the refractive power shortage is forcibly corrected by the second lens group, and spherical aberration is also deteriorated. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 20.00. In order to further secure the effect of the present embodiment, it is more preferable to set the upper limit of conditional expression (1) to 18.00.

Moreover, it is preferable that the photographic lens of the present application satisfies the following conditional expression (2) when the focal length of the first lens group is f1 and the focal length of the second lens group is f2.
(2) 4.10 <f2 / (-f1) <10.00

  Conditional expression (2) is a relational expression between the focal length of the first lens group and the focal length of the second lens group, and is a conditional expression for obtaining the optimum refractive power arrangement of the entire photographing lens system. By satisfying this conditional expression, it is possible to balance the refractive power in the entire photographic lens and reduce aberration fluctuations during focusing. For example, a photographic lens that can handle a focusing operation during movie shooting is provided. Can be provided.

  If the lower limit value of conditional expression (2) is not reached, the negative refractive power of the first lens group becomes small, and correction of coma aberration is insufficient, which is not preferable. In particular, sagittal coma aberration is deteriorated, which is not preferable. On the other hand, if the value is below the lower limit value, the positive refractive power of the second lens group becomes large, so that spherical aberration deteriorates from focusing on an object at infinity to focusing on a short distance object, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 4.20.

  If the upper limit value of conditional expression (2) is exceeded, the negative refractive power of the first lens group becomes large, so that correction of coma aberration becomes excessive. Particularly, sagittal coma and spherical aberration are deteriorated, which is not preferable. If the value exceeds the upper limit, the refractive power of the second lens group becomes small, and the amount of movement of the second lens group at the time of focusing becomes excessively large, and various aberrations, particularly distortion aberrations, become significantly negative. The entire photographic lens is undesirably enlarged. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 9.50. In order to further secure the effect of the present embodiment, it is more preferable to set the upper limit of conditional expression (2) to 8.00.

  With the above configuration, it is possible to provide a photographic lens, an optical apparatus, and a photographic lens manufacturing method that have less aberration fluctuations during focusing while being an optical system preceding a negative lens.

The photographic lens of the present application satisfies the following conditional expression (3), where f is the focal length of the entire photographic lens system when focusing on infinity and f2 is the focal length of the second lens group. Is preferred.
(3) 3.00 <f2 / f <30.00

  Conditional expression (3) is a relational expression between the focal length of the entire photographing lens system and the focal length of the second lens group, and is a conditional expression for defining an optimum refractive power arrangement of the second lens group.

  If the lower limit value of conditional expression (3) is not reached, the amount of movement of the second lens group during focusing can be reduced, but spherical aberration and particularly coma aberration worsen from focusing on an object at infinity to focusing on a short distance object. Therefore, it is not preferable. By making the second lens group have a refractive power of a certain amount with respect to the refractive power of the entire taking lens system, the amount of movement of the second lens group during focusing is reduced, and the second lens group and the second lens group The interval between the three lens groups can be reduced. As a result, fluctuations in field curvature can be suppressed and fluctuations in coma can be reduced. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 5.00. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (3) to 6.00.

  Exceeding the upper limit of conditional expression (3) is not preferable because the amount of movement of the second lens unit at the time of focusing becomes too large and fluctuations in various aberrations, particularly, distortion aberrations become negative. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 20.00. In order to further secure the effect of the present embodiment, it is more preferable to set the upper limit of conditional expression (3) to 16.00.

Further, in the photographic lens of the present application, when the focal length of the entire photographic lens system at the time of focusing on infinity is f and the combined focal length of the first lens component and the second lens component is fa, the following conditional expression ( It is preferable to satisfy 4).
(4) 0.50 <(− fa) / f <8.00

  Conditional expression (4) is a relational expression between the focal length of the entire photographing lens system and the combined focal length of the first lens component and the second lens component, and the first lens component and the second lens component in the first lens group. This is a conditional expression for obtaining the optimal refractive power arrangement.

  If the lower limit of conditional expression (4) is not reached, the combined refractive power of the first lens component and the second lens component becomes relatively large with respect to the focal length of the entire system, so that field curvature and coma are corrected. Becomes excessive. In particular, it is not preferable because sagittal coma aberration and field curvature are deteriorated. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.80. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (4) to 1.00.

  If the upper limit of conditional expression (4) is exceeded, the combined refractive power of the first lens component and the second lens component becomes relatively small with respect to the focal length of the entire taking lens system, so that field curvature and coma aberration Insufficient correction. In particular, sagittal coma aberration is deteriorated. In addition, the shortage of refractive power is forcibly corrected by the second lens component, and spherical aberration is also deteriorated. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 7.50. In order to further secure the effect of the present embodiment, it is more preferable to set the upper limit of conditional expression (4) to 5.00.

  In the photographic lens of the present application, it is preferable that the second lens group moves to the image side during focusing. With this configuration, the distance between the second lens group and the third lens group can be reduced, and fluctuations in field curvature can be suppressed.

  In the photographic lens of the present application, it is preferable that the first lens component is disposed on the most object side in the first lens group and has a negative meniscus shape with a convex surface facing the object side. With this configuration, it is possible to prevent the incident angle and the exit angle from becoming extremely large on each lens surface, and it is possible to easily perform aberration correction over a wide range of field angles. In general, the larger the incident angle of light with respect to a certain lens surface, the more aberration is generated. Therefore, it is not preferable to dispose a lens surface with an extremely large incident angle in the lens group on the object side of the wide-angle lens. According to the above configuration, the incident angle of light can be reduced, and the occurrence of aberration can be suppressed.

  The first lens group preferably has a third lens component having negative refractive power on the image side of the second lens component. With this configuration, the off-axis light beam can be gradually refracted by each lens component to gradually reduce the exit angle, thereby suppressing the occurrence of aberrations.

In addition, it is preferable that the photographing lens satisfies the following conditional expression (5) when the focal length of the first lens component is f11 and the focal length of the second lens component is f12.
(5) 0.60 <f11 / f12 <2.00

  Conditional expression (5) is a relational expression between the focal length of the first lens component and the focal length of the second lens component, and is a conditional expression for defining an optimum refractive power arrangement.

  If the lower limit of conditional expression (5) is not reached, the refractive power of the second lens component becomes too small with respect to the refractive power of the first lens component, and the field curvature, coma aberration and distortion can be corrected well. Since it disappears, it is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.75. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (5) to 0.85.

  When the upper limit value of conditional expression (5) is exceeded, the refractive power of the second lens component becomes larger than the refractive power of the first lens component, and it becomes impossible to correct field curvature, coma aberration, and distortion aberration in a balanced manner. Therefore, it is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 1.80.

  In addition, it is preferable that the photographing lens has an aperture stop between the second lens group and the third lens group. With this configuration, coma can be corrected well.

  The optical apparatus of the present application is characterized by having the photographing lens having the above-described configuration. As a result, it is possible to realize a high-performance optical apparatus that has an optical system preceding the negative lens and has little aberration fluctuation during focusing.

The manufacturing method of the photographic lens of the present application includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a first lens having a positive refractive power in order from the object side along the optical axis. A first lens component having a negative refractive power and a second lens component having a negative refractive power in order from the object side as the first lens group. And the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group is moved along the optical axis at the time of focusing. When the focal length of the entire system at the time of focusing is f, the focal length of the first lens component is f11, and the focal length of the second lens group is f2, the following conditional expressions (1) and (2) are satisfied. It arrange | positions so that it may carry out.
(1) 6.20 <(-f11) / f <25.00
(2) 4.10 <f2 // (-f) <10.00

  Accordingly, it is possible to manufacture a photographic lens with little aberration fluctuation at the time of focusing, although it is an optical system preceding the negative lens.

  Hereinafter, photographing lenses according to numerical examples of the present application will be described with reference to the accompanying drawings. 1, 3, 5, 7, and 9 show the lens configurations of the photographic lenses SL <b> 1 to SL <b> 5 according to the first to fifth embodiments, respectively.

  The photographing lenses SL1 to SL5 according to the respective examples have a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refractive power in order from the object side. And a third lens group G3.

  In each embodiment, the aperture stop S is disposed between the second lens group G2 and the third lens group G3.

  In focusing from an infinite object point to a short-distance object point, the first lens G1 and the third lens group G3 are fixed with respect to the image plane I, and the second lens group G2 is moved along the optical axis to the image plane I. Move to the side.

  A filter group FL composed of a low-pass filter, an infrared cut filter, and the like is disposed between the photographing lenses SL1 to SL5 and the image plane I.

  The image plane I is formed on an image pickup device (not shown), and the image pickup device is composed of, for example, a film, a CCD, a CMOS, or the like.

(First embodiment)
FIG. 1 is a cross-sectional view showing the lens configuration of the taking lens SL1 according to the first embodiment of the present application.

  In the photographing lens SL1, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 (first lens component) having a convex surface facing the object side, and a negative meniscus lens L12 (second lens) having a convex surface facing the object side. Lens component) and a negative negative meniscus lens L13 having a convex surface facing the object side and a cemented negative lens (third lens component) of a positive meniscus lens L14 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21 and a negative meniscus lens L22 having a concave surface facing the object side.

  The third lens group G3 is composed of, in order from the object side, a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a concave surface facing the object.

  Table 1 below shows values of specifications of the first embodiment.

  In [Surface data], “Surface number” is the order of the lens surfaces counted from the object side along the optical axis, “r” is the radius of curvature, and “d” is the surface interval (nth surface (n is an integer)). "Nd" represents the refractive index with respect to the d-line (wavelength 587.6 nm), and "νd" represents the Abbe number with respect to the d-line (wavelength 587.6 nm). “Object surface” indicates an object surface, “Variable” indicates a variable surface interval, “Aperture” indicates an aperture stop S, and “Image surface” indicates an image surface I. In the curvature radius “r”, “∞” indicates a plane, and the description of the refractive index nd = 1.0000 of air is omitted.

  In [Various data], “f” is the focal length, “FNo” is the F number, “2ω” is the angle of view (unit is “°”), “Y” is the image height, and “TL” is the photographing. “Bf” represents the total length of the lens (distance on the optical axis from the first surface of the lens surface to the image plane I), and “Bf” represents the back focus (air equivalent length). These values are those when focusing on infinity.

  [Variable interval data] indicates a variable interval in an infinitely focused state and a photographing magnification of -0.03. dn represents a variable surface interval of the nth surface.

  [Lens Group Data] indicates the start surface and focal length of each lens group.

  [Conditional Expression Corresponding Value] indicates the corresponding value of each conditional expression of the photographing lens according to the present embodiment.

  In general, “mm” is used as a unit for the focal length f, the radius of curvature r, the surface interval, and other lengths listed in all the following specification values. However, the photographic lens is not limited to this because the same optical performance can be obtained even when proportionally enlarged or reduced.

  The explanation of the above symbols and the specification table are the same in the following second to fifth embodiments.

[Table 1]
[Surface data]
Surface number r d nd νd
Object ∞
1 84.4180 1.41 1.6180 63.34
2 12.3327 8.00
3 22.3697 1.20 1.6180 63.34
4 8.9371 6.40
5 115.3703 2.00 1.6031 60.69
6 7.1469 4.66 1.8052 25.45
7 9.0782 Variable
8 18.0292 4.00 1.5174 52.20
9 -11.2689 1.20
10 -8.3383 0.60 1.8830 40.66
11 -12.1996 Variable
12 (Aperture) ∞ 3.50
13 22.1821 4.00 1.5932 67.90
14 -5.2628 0.50 1.8052 25.45
15 -8.9123 9.51
16 ∞ 0.50 1.5168 63.88
17 ∞ 1.11
18 ∞ 1.59 1.5168 63.88
19 ∞ 0.30
20 ∞ 0.70 1.5168 63.88
21 ∞ 0.70
Image plane ∞

[Various data]
f 2.96
FNo 2.76
2ω 181.59
Y 4.37
TL 64.87
Bf 14.41

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 85.91
d7 10.64 10.85
d11 2.35 2.14

[Lens group data]
Group Start surface Focal length
1 1 -4.547
2 8 23.026
3 13 13.566

[Conditional expression values]
(1) (−f11) /f=7.96
(2) f2 / (− f1) = 5.06
(3) f2 / f = 7.78
(4) (−fa) /f=3.45
(5) f11 / f12 = 0.94

  FIG. 2 is a diagram illustrating various aberrations of the photographic lens SL1 according to the first example. In each aberration diagram, “d” is d-line (wavelength 587.6 nm), “g” is various aberrations with respect to g-line (wavelength 435.8 nm), “A” is a light incident angle, that is, half angle of view (unit is “ ° ”). Those not specifically described represent various aberrations with respect to the d-line. The solid line in the astigmatism diagram indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the coma aberration diagram, for each incident angle, the solid line indicates the meridional coma aberration with respect to the d-line and the g-line. The explanations and symbols of the aberration diagrams are the same in the following examples.

  From each aberration diagram, it can be seen that the photographic lens SL1 according to the first example has a high optical performance with various aberrations corrected favorably.

(Second embodiment)
FIG. 3 is a cross-sectional view showing the lens configuration of the taking lens SL2 according to the second embodiment of the present application.

  In the photographic lens SL2, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 (first lens component) having a convex surface facing the object side, and a negative meniscus lens L12 (second lens) having a convex surface facing the object side. Lens component) and a cemented negative lens (third lens component) of a biconcave negative lens L13 and a positive meniscus lens L14 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a convex surface directed toward the object side, and a biconvex positive lens L22.

  The third lens group G3 is composed of a cemented lens of a negative meniscus lens L31 having a convex surface directed toward the object side and a biconvex positive lens L32 in order from the object side.

Table 2 below shows values of specifications of the second embodiment.
[Table 2]
[Surface data]
Surface number r d nd νd
Object ∞
1 52.6887 1.41 1.6180 63.34
2 17.1681 10.00
3 281.7230 1.20 1.6180 63.34
4 14.5574 5.40
5 -491.4031 1.80 1.6031 60.69
6 7.7005 4.70 1.8052 25.45
7 7.7854 Variable
8 16.5233 3.00 1.6889 31.16
9 10.4872 1.60
10 22.4091 1.40 1.8830 40.66
11 -34.6946 Variable
12 (Aperture) ∞ 3.20
13 11.7540 2.00 1.8467 23.80
14 5.8573 2.40 1.6030 65.44
15 -12.9247 10.40
16 ∞ 0.50 1.5168 63.88
17 ∞ 1.11
18 ∞ 1.59 1.5168 63.88
19 ∞ 0.30
20 ∞ 0.70 1.5168 63.88
21 ∞ 0.70
Image plane ∞

[Various data]
f 2.96
FNo 2.76
2ω 181.13
Y 4.36
TL 67.27
Bf 13.57

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 82.68
d7 16.49 16.70
d11 11.55 11.34

[Lens group data]
Group Start surface Focal length
1 1 -4.591
2 8 23.500
3 13 13.452

[Conditional expression values]
(1) (−f11) /f=14.15
(2) f2 / (− f1) = 5.12
(3) f2 / f = 7.94
(4) (−fa) /f=4.57
(5) f11 / f12 = 1.68

  FIG. 4 is a diagram illustrating various aberrations of the photographic lens SL2 according to the second example. From each aberration diagram, it can be seen that the photographic lens SL2 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 lens configuration of the taking lens SL3 according to the third example of the present application.

  In the photographic lens SL3, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 (first lens component) having a convex surface directed toward the object side, and a biconcave positive lens L12 (second lens component). And a cemented negative lens (third lens component) of a negative meniscus lens L13 having a convex surface facing the object side and a positive meniscus lens L14 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface facing the object side, a positive bilens lens L22, and a negative meniscus lens L23 having a concave surface facing the object side.

  The third lens group G3 includes, in order from the object side, a cemented lens of a positive meniscus lens L31 having a concave surface facing the object side and a negative meniscus lens L32 having a concave surface facing the object side, a biconvex positive lens L33, Consists of.

  When focusing from infinity to a short-distance object point, the aperture stop S moves to the image plane side together with the second lens group G2.

  Table 3 below shows values of specifications of the third embodiment.

[Table 3]
[Surface data]
Surface number r d nd νd
Object ∞
1 38.8527 1.41 1.6180 63.34
2 10.5822 8.30
3 -400.9567 1.11 1.6180 63.34
4 9.2882 6.11
5 25.1823 2.40 1.6400 60.20
6 5.9040 4.66 1.6990 30.13
7 10.5930 Variable
8 -6.1204 1.00 1.7174 29.57
9 -7.5971 1.00
10 13.4111 1.60 1.5182 58.82
11 -14.6431 1.20
12 -9.9426 0.78 1.7668 46.78
13 -11.7758 1.85
14 (Aperture) ∞ Variable
15 -20.3358 3.22 1.5182 58.82
16 -4.8511 0.40 1.7618 26.58
17 -9.8160 0.04
18 13.2730 1.40 1.6031 60.69
19 -39.5623 9.61
20 ∞ 0.50 1.5168 63.88
21 ∞ 1.11
22 ∞ 1.59 1.5168 63.88
23 ∞ 0.30
24 ∞ 0.70 1.5168 63.88
25 ∞ 0.70
Image plane ∞

[Various data]
f 2.96
FNo 2.76
2ω 180.69
Y 4.26
TL 63.88
Bf 14.51

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 86.16
d7 7.09 7.30
d14 5.82 5.60

[Lens group data]
Group Start surface Focal length
1 1 -4.593
2 8 19.389
3 15 14.473

[Conditional expression values]
(1) (−f11) /f=8.11
(2) f2 / (− f1) = 4.23
(3) f2 / f = 6.57
(4) (−fa) /f=2.52
(5) f11 / f12 = 1.63

  FIG. 6 is a diagram illustrating various aberrations of the taking lens SL3 according to the third example. From each aberration diagram, it can be seen that the photographic lens SL3 according to the third example has various optical aberrations corrected and high optical performance.

(Fourth embodiment)
FIG. 7 is a sectional view showing the lens configuration of the taking lens SL4 according to the fourth example of the present application.

  In the photographic lens SL4, in order from the object side, the first lens group G1 includes a negative meniscus lens L11 (first lens component) having a convex surface facing the object side and a negative meniscus lens L12 (second lens) having a convex surface facing the object side. Lens component) and a cemented negative lens (third lens component) of a biconcave negative lens L13 and a positive meniscus lens L14 having a convex surface facing the object side.

  The second lens group G2 includes a biconvex positive lens L21.

  The third lens group G3 includes a cemented lens which is formed by a biconvex positive lens L31 and a negative meniscus lens L32 having a concave surface directed toward the object side.

  When focusing from infinity to a short-distance object point, the aperture stop S moves to the image plane side together with the second lens group G2.

  Table 4 below lists values of specifications of the fourth embodiment.

[Table 4]
[Surface data]
Surface number r d nd νd
Object ∞
1 46.0563 1.41 1.6180 63.34
2 11.4000 6.80
3 21.6202 1.20 1.6180 63.34
4 7.2891 5.70
5 -143.4943 1.80 1.6780 50.67
6 8.6119 4.80 1.8467 23.80
7 20.1355 Variable
8 42.3589 4.00 1.5182 58.82
9 -42.0266 2.60
10 (Aperture) ∞ Variable
11 12.0821 4.00 1.6031 60.69
12 -6.4006 0.80 1.8607 23.08
13 -11.3581 9.51
14 ∞ 0.50 1.5168 63.88
15 ∞ 1.11
16 ∞ 1.59 1.5168 63.88
17 ∞ 0.30
18 ∞ 0.70 1.5168 63.88
19 ∞ 0.70
Image plane ∞

[Various data]
f 2.96
FNo 2.76
2ω 180.38
Y 4.23
TL 64.16
Bf 14.41

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 86.41
d7 10.00 10.40
d10 6.65 6.25

[Lens group data]
Group Start surface Focal length
1 1 -5.727
2 8 41.377
3 11 12.415

[Conditional expression values]
(1) (−f11) /f=8.42
(2) f2 / (− f1) = 7.31
(3) f2 / f = 14.16
(4) (−fa) /f=3.04
(5) f11 / f12 = 1.35

  FIG. 8 is a diagram illustrating all aberrations of the taking lens SL4 according to the fourth example. From each aberration diagram, it can be seen that the photographic lens SL4 according to the fourth example has a high optical performance with various aberrations corrected favorably.

(5th Example)
FIG. 9 is a cross-sectional view showing the lens configuration of the taking lens SL5 according to the fifth example of the present application.

  In the photographic lens SL5, in order from the object side, the first lens group G1 includes a negative meniscus lens L11 (first lens component) having a convex surface directed toward the object side and a negative meniscus lens L12 (second lens) having a convex surface directed toward the object side. Lens component), a negative meniscus lens L13 (third lens component) having a convex surface facing the object side, and a positive meniscus lens L14 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens L21 having a convex surface facing the object side, a positive meniscus lens L22 having a concave surface facing the object side, and a negative meniscus lens L23 having a concave surface facing the object side. A cemented lens.

  The third lens group G3 includes, in order from the object side, a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a concave surface facing the object side, and a biconvex positive lens L33.

  Table 5 below shows values of specifications of the fifth embodiment.

[Table 5]
[Surface data]
Surface number r d nd νd
Object ∞
1 52.4730 1.41 1.6180 63.34
2 11.7104 8.10
3 79.1630 1.11 1.6180 63.34
4 8.5436 6.00
5 166.0119 1.20 1.6400 60.20
6 7.4792 0.50
7 8.9057 4.66 1.6990 30.13
8 19.1173 Variable
9 8.7953 1.25 1.6477 33.73
10 26.2228 1.20
11 -40.3863 2.74 1.5182 58.82
12 -12.3220 0.77 1.8160 46.59
13 -22.7028 1.85
14 (Aperture) ∞ Variable
15 22.5794 3.22 1.5182 58.82
16 -5.1871 0.30 1.7618 26.58
17 -22.9110 0.04
18 12.0564 1.30 1.5168 63.88
19 -52.5820 9.34
20 ∞ 0.50 1.5168 63.88
21 ∞ 1.11
22 ∞ 1.59 1.5168 63.88
23 ∞ 0.30
24 ∞ 0.70 1.5168 63.88
25 ∞ 0.70
Image plane ∞

[Various data]
f 2.96
FNo 2.76
2ω 180.22
Y 3.86
TL 63.55
Bf 14.24

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 86.41
d8 11.83 12.04
d14 1.83 1.62

[Lens group data]
Group Start surface Focal length
1 1 -4.542
2 9 20.720
3 15 16.693

[Conditional expression values]
(1) (−f11) /f=8.36
(2) f2 / (− f1) = 4.57
(3) f2 / f = 7.02
(4) (−fa) /f=1.10
(5) f11 / f12 = 1.59

  FIG. 10 is a diagram illustrating various aberrations of the taking lens SL5 according to the fifth example. From each aberration diagram, it can be seen that the photographic lens SL5 according to the fifth example has various optical aberrations corrected and high optical performance.

  According to each of the above-described embodiments, it is possible to realize a photographing lens with little aberration fluctuation at the time of focusing while being an optical system preceding a negative lens. In addition, each said Example has shown one specific example of this invention, and this invention is not limited to these. The following contents can be appropriately adopted as long as the optical performance of the photographing lens of the present application is not impaired.

  Although a three-group configuration is shown as a numerical example of the photographic lens of the present application, the present application is not limited to this, and photographic lenses of other group configurations (for example, four groups) can also be configured. Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image side of the photographing lens of the present application may be used.

  In addition, in order to perform focusing from an object point at infinity to an object point at a short distance, the photographing lens of the present application uses a part of the lens group, the entire lens group, or a plurality of lens groups as the focusing lens group. It is good also as a structure moved to an optical axis direction. In particular, it is preferable that at least a part of the second lens group is a focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by an autofocus motor, such as an ultrasonic motor.

  Further, in the photographic lens of the present application, a blur detection system for detecting a blur of the lens system and a driving unit are combined with the lens system, and either the whole lens group or a part thereof is set as an anti-vibration lens group with respect to the optical axis. Image blur caused by camera shake or the like can also be corrected by moving so as to include a component in the vertical direction or by rotating (swinging) in an in-plane direction including the optical axis.

  The lens surface of the lens constituting the photographing lens of the present application may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are easy, and deterioration of optical performance due to errors in lens 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 aspherical, any of aspherical surface by grinding, a glass mold aspherical surface in which glass is molded into an aspherical shape, or a composite aspherical surface in which a resin provided on the glass surface is formed in an aspherical shape Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  In the photographic lens of the present application, it is preferable that the aperture stop is disposed between the second lens group and the third lens group, but instead of providing a member as an aperture stop, the role of the lens frame is substituted. Also good.

  Further, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the photographing lens of the present application. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.

  The photographing lens according to this embodiment has a focal length in terms of 35 mm film size of about 7.5 mm to 8.5 mm, preferably about 8 mm. In addition, the photographing lens according to the present embodiment has a distance (back focus) from the image side surface to the image plane of a lens disposed on the most image side that does not include a filter member such as a low-pass filter in terms of 35 mm film size, which is 10 mm. To about 20 mm, preferably about 12 mm to 15 mm.

  Next, a camera equipped with the photographing lens of the present application will be described with reference to FIG.

  FIG. 11 is a diagram illustrating a configuration of a camera including the photographing lens of the present application. As shown in FIG. 11, the camera 1 is a so-called mirrorless camera with interchangeable lenses provided with the photographic lens according to the first embodiment as the photographic lens 2.

  In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and is on the imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) (not shown). A subject image is formed on the screen. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.

  When the release button (not shown) is pressed by the photographer, the subject image generated by the shooting unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

  Here, the photographic lens according to the first embodiment mounted as the photographic lens 2 on the camera 1 is a photographic lens with a small aberration variation at the time of focusing while being an optical system preceding the negative lens. Therefore, the camera 1 can realize high-performance imaging with little aberration fluctuation during focusing. Even if a camera equipped with any of the photographing lenses according to the second to fifth embodiments as the photographing lens 2 is configured, the same effect as the camera 1 can be obtained. Even when the photographic lens according to each of the above embodiments is mounted on a single-lens reflex camera that has a quick return mirror and observes a subject with a finder optical system, the same effects as the camera 1 can be obtained.

  Hereinafter, the outline of the manufacturing method of the photographic lens of this application is demonstrated based on FIG.

  The manufacturing method of the photographing lens of the present application shown in FIG. 12 includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive lens in order from the object side along the optical axis. And a third lens group G3 having refracting power, and includes the following steps S1 to S3.

  As the first lens group G1, in order from the object side, a first lens component having a negative refractive power and a second lens component having a negative refractive power are arranged in the lens barrel (step S1). At this time, by providing a known moving mechanism in the lens barrel, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane during focusing, and the second lens group G2 is optical axis. (Step S2). Further, the first lens group G1, the second lens group G2, and the third lens group G3 are arranged so as to satisfy the above-described conditional expressions (1) and (2) (step S3).

  According to such a method for manufacturing a photographic lens of the present application, it is possible to manufacture a photographic lens with little aberration fluctuation at the time of focusing even though it is an optical system preceding a negative lens.

SL1 to SL5 Photography lens G1 First lens group G2 Second lens group G3 Third lens group FL Filter group I Image surface L11 First lens component L12 Second lens component S Aperture stop

Claims (11)

A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, substantially 3 in order from the object side along the optical axis. Consisting of a group of lenses
The first lens group includes, in order from the object side, a first lens component having negative refractive power and a second lens component having negative refractive power,
During focusing, the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group moves along the optical axis,
The lens component is a single lens or a cemented lens,
A photographic lens characterized by satisfying the following conditional expression:
7.00 <(− f11) / f <25.00
4.10 <f2 / (-f1) <10.00
However,
f: focal length of the entire photographing lens system at the time of focusing on infinity f1: focal length of the first lens group f11: focal length of the first lens component f2: focal length of the second lens group A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, substantially 3 in order from the object side along the optical axis. Consisting of a group of lenses
The first lens group includes, in order from the object side, a first lens component having negative refractive power and a second lens component having negative refractive power,
During focusing, the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group moves along the optical axis,
The lens component is a single lens or a cemented lens,
A photographic lens characterized by satisfying the following conditional expression:
6.20 <(− f11) / f <25.00
5.06 ≦ f2 / (− f1) <10.00
However,
f: focal length of the entire photographing lens system at the time of focusing on infinity f1: focal length of the first lens group f11: focal length of the first lens component f2: focal length of the second lens group   The photographic lens according to claim 1, wherein the first lens group includes three lenses having negative refractive power. Photographing lens according to any one of claims 1 to 3, characterized by satisfying the following conditional expression.
3.00 <f2 / f <30.00
However,
f: focal length of the whole photographing lens system at the time of focusing on infinity f2: focal length of the second lens group Photographing lens according to any one of claims 1 to 4, characterized by satisfying the following conditional expression.
0.50 <(-fa) / f <8.00
f: focal length of the entire photographing lens system at the time of focusing on infinity fa: synthetic focal length of the first lens component and the second lens component Wherein upon focusing, the imaging lens according to any one of claims 1 to 5 wherein the second lens group is characterized in that moves toward the image side. Wherein the first lens component, the first being arranged closest to the object side in the lens in group, any one of claims 1 to 6, characterized in that a negative meniscus shape with a convex surface directed to the object side The taking lens described in 1. Wherein the first lens group, the imaging lens according to any one of claims 1 to 7, characterized in that it has a third lens component having a negative refractive power on the image side of the second lens component. Photographing lens according to any one of claims 1 to 8, characterized by satisfying the following conditional expression.
0.60 <f11 / f12 <2.00
However,
f11: focal length of the first lens component f12: focal length of the second lens component The imaging lens according to any one of claims 1, characterized in that an aperture stop 9 between the second lens group and the third lens group. An optical apparatus comprising the photographing lens according to any one of claims 1 to 10 .

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