JP2015036779A - Photographing lens, optical apparatus, and method for manufacturing the photographing lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system that has high optical performance and can be downsized with a reduced number of lenses, in consideration that lenses having higher performance and more compact sizes than conventional lenses are required in association with recent increases in the number of pixels of an imaging device.SOLUTION: A photographing lens composed of seven lenses in an entire system comprises, in order from an object side along an optical axis: a first lens component L11 having negative refractive power; and a second lens component L12 having negative refractive power. The photographing lens satisfies a predetermined conditional expression.

Description

  The present invention relates to a photographic lens, an optical apparatus including the photographic lens, and a method for manufacturing the photographic lens.

  Conventionally, a wide-angle lens in which two negative lenses are arranged on the most object side is known (see, for example, Patent Document 1).

JP 2006-337691 A

  However, with the recent increase in the number of pixels in an image sensor, provision of a lens with higher performance and compactness than before has been demanded.

  Accordingly, an object of the present invention is to provide a photographic lens, an optical apparatus, and a photographic lens manufacturing method that have high optical performance and can be miniaturized with a small number of lenses.

In order to solve the above problems, in the present invention,
The entire system consists of 7 lenses,
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 along the optical axis,
A photographic lens characterized by satisfying the following conditional expression is provided.
8.00 <(-f11) / f <14.50
2.60 <(-fa) / f <15.00
However,
f: Focal length of the entire photographing lens system at the time of focusing on infinity f11: Focal length fa of the first lens component fa: Composite focal length of the first lens component and the second lens component

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

Further, in order to solve the above problems, the present invention
A manufacturing method of a photographic lens consisting of seven lenses in the whole system,
A first lens component having negative refractive power and a second lens component having negative refractive power are arranged in order from the object side along the optical axis,
A photographing lens manufacturing method is provided, wherein the seven lenses are arranged so as to satisfy the following conditional expression.
8.00 <(-f11) / f <14.50
2.60 <(-fa) / f <15.00
However,
f: Focal length of the entire photographing lens system at the time of focusing on infinity f11: Focal length fa of the first lens component fa: Composite focal length of the first lens component and the second lens component

  According to the present invention, it is possible to provide a photographic lens, an optical apparatus, and a photographic lens manufacturing method that have high optical performance and can be miniaturized with a small number of lenses.

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 infinitely focused state. It is sectional drawing which shows the lens structure of the photographic lens which concerns on 2nd Example of this application. FIG. 10 is a diagram illustrating various aberrations of the taking lens according to the second 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 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 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 photographic lens of the present application is composed of seven lenses in the entire system, and in order from the object side along the optical axis, a first lens component having a negative refractive power, a second lens component having a negative refractive power, have. With this configuration, it is possible to correct aberrations with good off-axis aberrations, and it is possible to widen the angle of the photographing lens. In the present application, the lens component refers to a single lens or a cemented lens formed by cementing two or more lenses.

Further, the photographing lens of the present application satisfies the following conditional expression (1), where f is the focal length of the entire photographing lens system at the time of focusing on infinity and f11 is the focal length of the first lens component. It is preferable to do.
(1) 8.00 <(-f11) / f <14.50

  Conditional expression (1) is a relational expression between the focal length of the entire photographing lens system and the focal length of the first lens component, and is a conditional expression for defining an optimum refractive power arrangement of the entire photographing lens.

  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 8.20.

  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, it is not preferable because it is necessary to forcibly correct the shortage of refractive power by the second lens group, and the spherical aberration also deteriorates. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (1) to 14.00.

Further, it is preferable that the photographing lens satisfies the following conditional expression (2) when the combined focal length of the first lens component and the second lens component is fa.
(2) 2.60 <(-fa) / f <15.00

  Conditional expression (2) 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 optimum refractive power of the first lens component and the second lens component. It is a conditional expression for prescribing the arrangement.

  If the lower limit of conditional expression (2) 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 (2) to 2.70. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (2) to 2.80.

  When the upper limit of conditional expression (2) 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 system, and the correction of field curvature and coma aberration is insufficient. This is not preferable. In particular, sagittal coma aberration is deteriorated. In addition, the insufficient 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 (2) to 10.00. 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 that has high optical performance and can be miniaturized with a small number of lenses of seven.

  In addition, the photographing lens of the present application includes, in order from the object side along the optical axis, the first lens component including the first lens component and the second lens component and having a negative refractive power, and a positive refractive power. A second lens group having a positive refractive power, and a second lens group having a positive refracting power, and the second lens group so that a distance between the first lens group and the second lens group changes during focusing. The lens group preferably moves along the optical axis and has an aperture stop between the second lens group and the third lens group. In the present application, the lens group refers to a portion having at least one lens separated by an aperture stop or an air interval that changes during focusing.

  With the configuration of the first lens group to the third lens group, it is possible to correct aberrations centering on off-axis aberrations. Moreover, coma can be favorably corrected by the arrangement of the aperture stop.

Moreover, it is preferable that the photographic lens of the present application satisfies the following conditional expression (3) when the focal length of the second lens group is f2.
(3) 4.50 <f2 / f <20.00

  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. 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 6.50.

  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 various aberrations, particularly distortion aberrations, become prominent. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (3) to 15.00.

  In the photographic lens of the present application, the second lens group and the aperture stop move integrally along the optical axis at the time of focusing, or the second lens group and the third lens group are integrated. It is preferable to move along the optical axis.

  In addition, the photographic lens of the present application adopts an inner focus method that changes the distance of a part of the lens system to reduce fluctuations in field curvature when focusing from an object at infinity to a close object. doing. Further, by adopting a configuration in which focusing is performed by the second lens group or the second lens group and the third lens group capable of reducing the aperture, the focusing weight (the weight of the lens driven at the time of focusing) is light. Therefore, it becomes possible to focus more quickly.

  In the photographic lens of the present application, it is preferable that the first lens component 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 with respect to a certain lens surface, the more aberration is generated. Therefore, it is not preferable to dispose a lens surface having an extremely large incident angle in the lens group on the object side of the wide-angle lens.

  In the photographing lens of the present application, it is preferable that the first lens group has a third lens component having a negative refractive power closer to the image plane side than the second lens component.

  With this configuration, it is possible to gradually refract the off-axis light beam and gradually reduce the emission angle to suppress occurrence of aberration.

  The optical apparatus of the present application is characterized by having the above-described photographing lens. Accordingly, it is possible to realize an optical device that has high optical performance and can be miniaturized with a small number of lenses.

The photographic lens manufacturing method of the present application is a photographic lens manufacturing method including seven lenses in the entire system, and includes a first lens component having negative refractive power in order from the object side along the optical axis, and a negative lens power. A second lens component having a refractive power of f, the focal length of the entire photographic lens system at the time of focusing on infinity is f, the focal length of the first lens component is f11, the first lens component and the first lens component. When the combined focal length of the two lens components is fa, it is arranged so as to satisfy the following conditional expression.
8.00 <(-f11) / f <14.50
2.60 <(-fa) / f <15.00

  Accordingly, it is possible to manufacture a photographing lens that has high optical performance and can be miniaturized with a small number of lenses.

  Hereinafter, photographing lenses according to numerical examples of the present application will be described with reference to the accompanying drawings. 1, 3, 5, and 7 show the lens configurations of the photographic lenses SL <b> 1 to SL <b> 4 according to the first to fourth embodiments, respectively.

  The photographic lenses SL1 to SL4 according to the respective examples have, in order from the object side, a first lens G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refractive power. The third lens group G3. In each embodiment, the aperture stop S is located between the second lens group G2 and the third lens group G3.

  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 SL4 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 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 is composed of a biconvex positive lens L21.

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

  In the photographic lens SL1, the second lens group G2, the aperture stop S, and the third lens group G3 are integrally moved to the object side along the optical axis, so that the object point from the infinity object point is adjusted to the near object point. Do chariot.

  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 conversion 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. d0 represents the distance on the optical axis from the object to the first 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 optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.

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

[Table 1]
[Surface data]
Surface number r d nd νd
Object ∞
1 41.5279 1.40 1.6180 63.34
2 11.4000 6.80
3 24.5552 1.25 1.6180 63.34
4 7.0026 5.80
5 -668.4521 1.60 1.6667 48.33
6 7.6029 5.00 1.8467 23.80
7 14.5475 Variable
8 39.0559 3.40 1.6127 58.54
9 -35.4313 2.60
10 (Aperture) ∞ 6.65
11 12.7543 4.20 1.6204 60.25
12 -6.7063 0.80 1.8607 23.08
13 -12.4867 Variable
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 180.99
Y 4.23
TL 63.71
Bf 13.46

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 86.29
d7 9.80 9.50
d13 9.51 9.81

[Lens group data]
Group Start surface Focal length
1 1 -4.948
2 8 30.855
3 11 12.978

[Conditional expression values]
(1) (−f11) /f=8.75
(2) (−fa) /f=2.87
(3) f2 / f = 10.43

  The combined focal length of the second lens group G2 and the third lens group G3 is 12.502 mm.

  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 the respective aberration diagrams, it can be seen that the photographic lens SL1 according to the first example has excellent optical performance with various aberrations corrected well.

(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 biconcave negative 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 is composed of a biconvex positive lens L21.

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

  In the photographic lens SL2, the second lens group G2, the aperture stop S, and the third lens group G3 are integrally moved along the optical axis toward the object side, thereby focusing from an infinite object point to a short-distance object point. I do.

Table 2 below shows values of specifications of the second embodiment.
[Table 2]
[Surface data]
Surface number r d nd νd
Object ∞
1 48.7490 1.41 1.6180 63.34
2 15.7905 10.00
3 -294.5503 1.20 1.6180 63.34
4 20.8282 5.40
5 71.4927 1.80 1.6031 60.69
6 7.0560 4.70 1.8052 25.45
7 6.4060 Variable
8 30.5957 2.80 1.5400 59.52
9 -20.9856 11.55
10 (Aperture) ∞ 3.20
11 8.6789 2.00 1.8467 23.80
12 4.8847 2.40 1.6030 65.44
13 -22.9685 Variable
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 180.35
Y 4.31
TL 67.27
Bf 11.86

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 82.72
d7 16.49 16.33
d13 10.40 10.55

[Lens group data]
Group Start surface Focal length
1 1 -4.591
2 8 23.500
3 11 13.452

[Conditional expression values]
(1) (−f11) /f=12.99
(2) (−fa) /f=5.10
(3) f2 / f = 7.94

  The combined focal length of the second lens group G2 and the third lens group G3 is 12.445 mm.

  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 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, in order from the object side, a cemented positive lens including a biconvex positive lens L31 and a negative meniscus lens L32 having a concave surface directed toward the object side.

  In the photographic lens SL3, the second lens group G2 and the aperture stop S are moved integrally along the optical axis to the image side, thereby focusing from an infinite object point to a short-distance object point.

Table 3 below shows values of specifications of the third embodiment.
[Table 3]
[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=8.41
(2) (−fa) /f=3.03
(3) f2 / f = 13.98

  The combined focal length of the second lens group G2 and the third lens group G3 is 12.330 mm.

  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 diagram showing the configuration of the taking lens SL4 according to the fourth embodiment of the present invention.

  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. 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, in order from the object side, a cemented positive lens including a biconvex positive lens L31 and a negative meniscus lens L32 having a concave surface directed toward the object side.

  In the photographic lens SL4, the first lens group G1, the second lens group G2, the aperture stop S, and the third lens group G3 are moved toward the object side along the optical axis, respectively. Focus on a short distance object point.

Table 4 below shows values of specifications of the fourth embodiment.
[Table 4]
[Surface data]
Surface number r d nd νd
1 36.0092 1.50 1.6180 63.34
2 11.4000 6.60
3 17.5058 1.20 1.6180 63.34
4 7.5892 5.70
5 -106.3611 1.80 1.6780 50.67
6 7.4284 4.80 1.8467 23.80
7 10.5319 Variable
8 25.2998 4.20 1.5182 58.82
9 -25.3485 2.60
10 (aperture) ∞ variable
11 12.8237 3.80 1.5891 61.22
12 -6.4715 1.00 1.8467 23.80
13 -11.6377 Variable
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

[Various data]
f 2.96
FNo 2.80
2ω 180.80
Y 4.23
TL 64.26
Bf 14.41

[Variable interval data]
Magnification at infinity -0.03
d0 ∞ 88.45
d7 10.00 9.66
d10 6.65 6.75
d13 6.65 9.75

[Lens group data]
Lens group Start surface Focal length
1 1 -4.485
2 8 25.145
3 11 13.358

[Conditional expression values]
(1) (−f11) /f=9.32
(2) (−fa) /f=3.67
(3) f2 / f = 8.50

  The combined focal length of the second lens group G2 and the third lens group G3 is 12.820.

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

 According to each of the above embodiments, it is possible to realize a photographing lens that has high optical performance and can be miniaturized with a small number of lenses. 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, the photographic lens of the present application uses a part of a lens group, an entire lens group, or a plurality of lens groups as a focusing lens group for focusing from an object point at infinity to a near object point. It is good also as a structure moved to a direction. In the photographic lens of the present application, the entire second lens group is the focusing lens group, but a part of the second lens group may be the focusing lens group. In particular, it is preferable that at least a part of the second lens group or at least a part of the third 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. Note that the focusing lens group is a portion of an optical system that includes one or more lenses that move along the optical axis during focusing and that is separated by an air interval that changes during focusing.

  In the photographic lens of the present application, the photographic lens is combined with a blur detection system for detecting blur of the photographic lens and a driving means, 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 of the 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 to 8 mm To about 20 mm, preferably about 11 mm to 15 mm.

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

  FIG. 9 is a diagram illustrating a configuration of a camera including the photographing lens of the present application. As shown in FIG. 9, the camera 1 is a so-called mirrorless camera with interchangeable lenses provided with the photographic lens SL <b> 1 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 photographing lens SL1 according to the first embodiment mounted as the photographing lens 2 on the camera 1 is a photographing lens that has high optical performance and can be miniaturized with a small number of lenses. Therefore, this camera 1 can realize high optical performance and downsizing. Even if a camera equipped with any of the photographing lenses according to the second to fourth 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, an outline of a manufacturing method of the photographing lens of the present application will be described with reference to FIG.

  The photographic lens manufacturing method of the present application shown in FIG. 12 is a photographic lens manufacturing method including seven lenses in the entire system, and includes the following steps S1 to S2.

  As the first lens group G1, a first lens component having a negative refractive power and a second lens component having a negative refractive power are arranged in this order from the object side (step S1). Further, the seven lenses are arranged so as to satisfy the conditional expressions (1) and (2) (step S2).

  According to the method for manufacturing a photographic lens of the present application, it is possible to manufacture a photographic lens that has high optical performance and can be miniaturized with a small number of lenses.

SL1 to SL4 Shooting lens G1 First lens group G2 Second lens group FL Filter group I Image plane L11 First lens component L12 Second lens component S Aperture stop

Claims (9)

The entire system consists of 7 lenses,
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 along the optical axis,
A photographic lens characterized by satisfying the following conditional expression:
8.00 <(-f11) / f <14.50
2.60 <(-fa) / f <15.00
However,
f: Focal length of the entire photographing lens system at the time of focusing on infinity f11: Focal length fa of the first lens component fa: Composite focal length of the first lens component and the second lens component A first lens group including the first lens component and the second lens component in order from the object side along the optical axis, and having negative refractive power;
A second lens group having a positive refractive power;
A third lens group having a positive refractive power,
The second lens group moves along the optical axis so that the distance between the first lens group and the second lens group changes during focusing,
The photographic lens according to claim 1, further comprising an aperture stop between the second lens group and the third lens group. The photographing lens according to claim 2, wherein the following conditional expression is satisfied.
4.50 <f2 / f <20.00
However,
f: Focal length of the entire photographing lens system at the time of focusing on infinity f2: Focal length of the second lens group   4. The photographic lens according to claim 2, wherein the second lens group and the aperture stop integrally move along the optical axis during focusing. 5.   4. The photographic lens according to claim 2, wherein the second lens group and the third lens group integrally move along the optical axis during focusing. 5.   The photographic lens according to claim 1, wherein the first lens component has a negative meniscus shape with a convex surface facing the object side.   7. The photographic lens according to claim 1, wherein the first lens group includes a third lens component having a negative refractive power closer to the image plane than the second lens component. .   An optical apparatus comprising the photographing lens according to claim 1. A manufacturing method of a photographic lens consisting of seven lenses in the whole system,
A first lens component having negative refractive power and a second lens component having negative refractive power are arranged in order from the object side along the optical axis,
A method of manufacturing a photographic lens, wherein the seven lenses are arranged so as to satisfy the following conditional expression:
8.00 <(-f11) / f <14.50
2.60 <(-fa) / f <15.00
However,
f: Focal length of the entire photographing lens system at the time of focusing on infinity f11: Focal length fa of the first lens component fa: Composite focal length of the first lens component and the second lens component

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