JP2013025161A - Imaging lens, optical device having the same, and method for manufacturing imaging lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging lens having excellent optical performance and focusing performance, an optical device having the imaging lens, and a method for manufacturing the imaging lens.SOLUTION: An imaging lens SL used for a camera 1 or the like comprises, in order from an object side: a first lens group G1 having a positive refractive power; a second lens group G2 having a positive refractive power; and a third lens group G3 having a positive refractive power. In focusing, the first lens group G1 and the third lens group G3 are fixed with respect to an image plane, and the second lens group G2 moves along the optical axis.

Description

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

  Conventionally, an inner focus type photographing lens suitable for a photographic camera or a video camera has been proposed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-199066

  However, because the specifications of the lenses used in the focusing group have not been optimized, the conventional inner focus photographic lens achieves high focusing performance while maintaining good optical performance from infinity to close range. There was a problem that it was difficult to do.

  The present invention has been made in view of such problems, and an object thereof is to provide a photographing lens having good optical performance and focusing performance, an optical apparatus having the photographing lens, and a method for manufacturing the photographing lens. And

In order to solve the above problems, a photographic lens according to the present invention has, in order from the object side, a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a positive refractive power. The first lens group and the third lens group are fixed with respect to the image plane, the second lens group moves along the optical axis, and the following conditional expression: It is characterized by satisfying.
70 <f1 / f <300
However,
f1: Focal length of the first lens unit f: Focal length of the entire system when focusing on infinity

Moreover, it is preferable that such a photographic lens satisfies the following conditional expressions.
60 <f1 / f2 <350
However,
f2: Focal length of the second lens group

Moreover, it is preferable that such a photographic lens satisfies the following conditional expressions.
20 <f1 / f3 <90
However,
f3: focal length of the third lens unit

Moreover, it is preferable that such a photographic lens satisfies the following conditional expressions.
0.70 <r1 / f2 <1.05
However,
r1: radius of curvature of the lens surface closest to the object side of the second lens group f2: focal length of the second lens group

Moreover, it is preferable that such a photographic lens satisfies the following conditional expressions.
0.80 <f21 / f <1.20
However,
f21: Focal length of the lens arranged closest to the object side in the second lens group

Moreover, it is preferable that such a photographic lens satisfies the following conditional expressions.
0.80 <f21 / f2 <1.50
However,
f21: Focal length of the lens disposed closest to the object side of the second lens group f2: Focal length of the second lens group

  In such a photographing lens, it is preferable that the first lens group includes a positive lens, a negative lens, and a negative lens in order from the object side.

  In such a photographing lens, it is preferable that the most image side lens of the second lens group has a biconvex shape.

  In addition, such a photographing lens preferably has an aperture stop in the second lens group.

  An optical apparatus according to the present invention includes any one of the above-described photographing lenses.

Further, in the manufacturing method of the photographing lens according to the present invention, in order from the object side, a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens having a positive refractive power. A first lens group and a third lens group that are fixed with respect to the image plane, and the second lens group moves along the optical axis during focusing. It arrange | positions so that the following conditional expressions may be satisfied.
70 <f1 / f <300
However,
f1: Focal length of the first lens unit f: Focal length of the entire system when focusing on infinity

  ADVANTAGE OF THE INVENTION According to this invention, the imaging lens which has favorable optical performance and focusing performance, the optical apparatus which has this imaging lens, and the manufacturing method of an imaging lens can be provided.

It is sectional drawing which shows the structure of the photographic lens concerning 1st Example. FIG. 4A is a diagram illustrating various aberrations of the taking lens according to Example 1, wherein (a) shows an infinite focus state, and (b) shows a close focus state (D0 = 700 mm). It is sectional drawing which shows the structure of the photographic lens which concerns on 2nd Example. FIG. 6 is a diagram illustrating various aberrations of the taking lens according to Example 2, wherein (a) shows an infinite focus state, and (b) shows a short distance focus state (D0 = 700 mm). It is sectional drawing which shows the structure of the photographic lens which concerns on 3rd Example. FIG. 5A is a diagram illustrating various aberrations of the taking lens according to Example 3, wherein (a) illustrates an infinite focus state, and (b) illustrates a close focus state (D0 = 700 mm). It is sectional drawing which shows the structure of the photographic lens which concerns on 4th Example. FIG. 5A is a diagram illustrating various aberrations of the taking lens according to Example 4, wherein (a) shows an infinite focus state, and (b) shows a close focus state (D0 = 700 mm). 1 is a cross-sectional view of a camera equipped with a photographic lens according to the present embodiment. It is a flowchart for demonstrating the manufacturing method of the imaging lens which concerns on this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the photographic lens SL according to this embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a positive And a third lens group G3 having refractive power. With this configuration, it is possible to satisfactorily correct the downsizing of the lens barrel and each aberration. Further, when the photographing lens SL focuses on an object at a short distance from infinity, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 is along the optical axis. Move. With such a configuration, it is possible to satisfactorily correct the aberration variation of the lens barrel and focusing.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (1).

70 <f1 / f <300 (1)
However,
f1: Focal length of the first lens group G1 f: Focal length of the entire system when focusing on infinity

  Conditional expression (1) defines the ratio between the focal length f1 of the first lens group G1 and the focal length f of the entire system in the infinitely focused state. The photographic lens SL can achieve good optical performance by satisfying conditional expression (1).

  When the upper limit of conditional expression (1) is exceeded, the refractive power of the first lens group G1 becomes weak, and when focusing on an object at a close distance, the spherical aberration is overcorrected and the field curvature is undercorrected. It becomes difficult to correct the curvature of field at the same time. The effect of the present application can be ensured by setting the upper limit value of conditional expression (1) to 270.

  If the lower limit of conditional expression (1) is not reached, the refractive power of the first lens group G1 becomes strong, and when focusing on an object at a close distance, the spherical aberration is insufficiently corrected and the curvature of field becomes overcorrected. It becomes difficult to correct aberration and curvature of field simultaneously. The effect of the present application can be ensured by setting the lower limit value of conditional expression (1) to 75.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (2).

60 <f1 / f2 <350 (2)
However,
f1: Focal length of the first lens group G1 f2: Focal length of the second lens group G2

  Conditional expression (2) defines the ratio between the focal length f1 of the first lens group G1 and the focal length f2 of the second lens group G2. The present photographing lens SL can achieve good optical performance by satisfying conditional expression (2).

  If the upper limit value of conditional expression (2) is exceeded, the refractive power of the second lens group G2 becomes strong, and when focusing on an object at close range, the spherical aberration is overcorrected and the field curvature is undercorrected, resulting in spherical aberration. It becomes difficult to correct the curvature of field at the same time. The effect of the present application can be ensured by setting the upper limit value of conditional expression (2) to 320.

  If the lower limit value of conditional expression (2) is not reached, the refractive power of the first lens group G1 becomes strong, and when focusing on an object at a close distance, the spherical aberration is insufficiently corrected and the field curvature becomes excessively corrected, resulting in a spherical surface. It becomes difficult to correct aberration and curvature of field simultaneously. The effect of the present application can be ensured by setting the lower limit value of conditional expression (2) to 70.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (3).

20 <f1 / f3 <90 (3)
However,
f1: Focal length of the first lens group G1 f3: Focal length of the third lens group G3

  Conditional expression (3) defines the ratio between the focal length f1 of the first lens group G1 and the focal length f3 of the third lens group G3. The present photographing lens SL can realize good optical performance by satisfying conditional expression (3).

  If the upper limit value of conditional expression (3) is exceeded, the refractive power of the third lens group G3 becomes strong, and when focusing on an object at a close distance, the spherical aberration is insufficiently corrected and the field curvature becomes excessively corrected, resulting in spherical aberration. It becomes difficult to correct the curvature of field at the same time. The effect of the present application can be ensured by setting the upper limit value of conditional expression (3) to 85.

  On the other hand, if the lower limit of conditional expression (3) is not reached, the refractive power of the first lens group G1 becomes strong and it becomes difficult to correct spherical aberration. The effect of the present application can be ensured by setting the lower limit value of conditional expression (3) to 25.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (4).

0.70 <r1 / f2 <1.05 (4)
However,
r1: radius of curvature of the lens surface closest to the object side of the second lens group G2 f2: focal length of the second lens group G2

  Conditional expression (4) defines the ratio between the radius of curvature r1 of the lens surface closest to the object side of the second lens group G2 and the focal length of the second lens group G2. The present photographing lens SL can realize good optical performance by satisfying conditional expression (4).

  If the upper limit of conditional expression (4) is exceeded, it will be difficult to correct fluctuations in spherical aberration and coma due to focusing. In addition, the effect of this application can be ensured by making the upper limit of conditional expression (4) into 1.00.

  If the lower limit of conditional expression (4) is not reached, it will be difficult to correct fluctuations in spherical aberration and coma due to focusing. The effect of the present application can be ensured by setting the lower limit of conditional expression (4) to 0.75.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (5).

0.80 <f21 / f <1.20 (5)
However,
f21: Focal length of the lens disposed closest to the object side in the second lens group G2 f: Focal length of the entire system when focusing on infinity

  Conditional expression (5) defines the ratio between the focal length f21 of the lens disposed closest to the object side of the second lens group G2 and the focal length f of the entire system at infinity. The present photographing lens SL can realize good optical performance by satisfying conditional expression (5).

  If the upper limit value of the conditional expression (5) is exceeded, the refractive power of the lens disposed closest to the object side in the second lens group G2 becomes weak, and it becomes difficult to correct variations due to focusing of spherical aberration and field curvature. . The effect of the present application can be ensured by setting the upper limit value of conditional expression (5) to 1.10.

  If the lower limit value of conditional expression (5) is not reached, the refractive power of the lens disposed closest to the object side in the second lens group G2 becomes strong, and it becomes difficult to correct spherical aberration. The effect of the present application can be ensured by setting the lower limit of conditional expression (5) to 0.85.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (6).

0.80 <f21 / f2 <1.50 (6)
However,
f21: Focal length of the lens disposed closest to the object side of the second lens group G2 f2: Focal length of the second lens group G2

  Conditional expression (6) defines the ratio between the focal length f21 of the lens disposed closest to the object side of the second lens group G2 and the focal length f2 of the second lens group G2. The present photographing lens SL can realize good optical performance by satisfying conditional expression (6).

  If the upper limit value of conditional expression (6) is exceeded, the refractive power of the lens disposed closest to the object side in the second lens group G2 becomes weak, and it becomes difficult to correct variations due to focusing of spherical aberration and field curvature. . The effect of the present application can be ensured by setting the upper limit value of conditional expression (6) to 1.30.

  If the lower limit value of conditional expression (6) is not reached, the refractive power of the lens arranged closest to the object side in the second lens group G2 becomes strong, and it becomes difficult to correct spherical aberration. Note that the effect of the present application can be ensured by setting the lower limit of conditional expression (6) to 0.85.

  In the photographing lens SL, it is preferable that the first lens group G1 includes a positive lens, a negative lens, and a negative lens in order from the object side. With such a configuration, spherical aberration and curvature of field can be favorably corrected.

  In the photographing lens SL, it is preferable that the most image side lens of the second lens group G2 has a biconvex lens shape. With such a configuration, spherical aberration and coma can be favorably corrected.

  The photographing lens SL preferably has an aperture stop S in the second lens group G2. With such a configuration, coma can be corrected well.

  Next, a camera equipped with the optical system OS of the present application will be described with reference to FIG. FIG. 9 is a diagram illustrating a configuration of a camera including the optical system OS of the present application. As shown in FIG. 9, the camera 1 is a so-called mirrorless camera of an interchangeable lens provided with the above-described optical system OS as a 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.

  Further, when a release button (not shown) is pressed by the photographer, an image photoelectrically converted by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1. In this embodiment, an example of a mirrorless camera has been described. However, an optical system OS according to this embodiment is mounted on a single-lens reflex camera that has a quick return mirror in the camera body and observes a subject using a finder optical system. Even in this case, the same effect as the camera 1 can be obtained.

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

  In the present embodiment, the photographing lens SL having a three-group configuration is shown. However, the above-described configuration conditions and the like can be applied to other group configurations such as the fourth group and the fifth group. 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 focusing.

  The second lens group G2, which is the focusing lens group described above, can also be applied to autofocus and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like).

  Also, by moving the lens group or partial lens group so that it has a component in the direction perpendicular to the optical axis, or rotating (swinging) in the in-plane direction including the optical axis, image blur caused by camera shake is corrected. An anti-vibration lens group may be used. In particular, the second lens group G2 is preferably an anti-vibration lens group.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. It is preferable that the lens surface is a spherical surface or a flat surface because lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in processing and assembly adjustment is prevented. 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.

  Hereinafter, an outline of a method for manufacturing the photographing lens SL of the present embodiment will be described with reference to FIG. First, each lens is arranged and a lens group is prepared (step S100). Specifically, in the present embodiment, for example, as shown in FIG. 1, in order from the object side, a positive meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and an object A negative meniscus lens L13 having a convex surface on the side is disposed to form the first lens group G1, and in order from the object side, a positive meniscus lens L21 having a convex surface on the object side, a biconcave lens L22, and a positive surface having a convex surface directed to the image side A meniscus lens L23 and a biconvex lens L24 are arranged to form the second lens group G2, and a cemented negative lens CL31 of the biconvex lens L31 and the biconcave lens L32 and a positive meniscus lens L33 having a convex surface facing the object side are arranged. The third lens group G3. The aperture stop S is disposed between the positive meniscus lens L21 and the biconcave lens L22 of the second lens group G2. The lens groups prepared in this way are arranged to manufacture the photographing lens SL.

  At this time, in focusing, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 is arranged to move along the optical axis (step S200). Further, the first lens group G1, the second lens group G2, and the third lens group G3 are arranged so as to satisfy the conditional expression (1) (step S300).

  Hereinafter, each example of the present application will be described with reference to the drawings. 1, 3, 5, and 7 illustrate the configuration of the photographic lens SL (SL <b> 1 to SL <b> 4) according to each embodiment and the movement of each lens group in a change in focus state from an infinite distance to a close object. It is sectional drawing which shows a mode.

[First embodiment]
FIG. 1 is a diagram illustrating a configuration of a photographic lens SL1 according to the first example. The photographing lens SL1 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, It is comprised. The first lens group G1, in order from the object side, includes a positive meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a negative meniscus lens L13 having a convex surface directed toward the object side. Composed. 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 biconcave lens L22, a positive meniscus lens L23 having a convex surface facing the image side, and a biconvex lens L24. The The third lens group G3 includes, in order from the object side, a cemented negative lens CL31 of a biconvex lens L31 and a biconcave lens L32, and a positive meniscus lens L33 having a convex surface facing the object side.

  Thus, in the photographic lens SL1 according to the first example, the first lens group G1 includes a positive lens, a negative lens, and a negative lens in order from the object side. In the second lens group G2, the most image-side lens has a biconvex shape (biconvex lens L24). The aperture stop S is disposed between the positive meniscus lens L21 and the biconcave lens L22 in the second lens group G2. A filter group FL including a low-pass filter and an infrared cut filter is disposed between the photographing lens SL1 and the image plane I.

  In the photographic lens SL1 according to the first example having such a configuration, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G3 is fixed at the time of focusing from infinity to a close object. The lens group G2 moves in the object direction along the optical axis. The aperture stop S moves together with the second lens group G2 when focusing.

  Table 1 below lists values of specifications of the photographing lens SL1 according to the first example. In the overall specifications of Table 1, f is the focal length of the entire system, FNO is the F number, 2ω is the angle of view, Y is the image height, TL is the full length, and Bf is the back focus. The total length TL indicates the distance on the optical axis from the most object side lens surface (first surface) to the image plane I at the time of focusing on infinity, and the back focus is the most image side lens surface (20th lens surface). The distance on the optical axis from the surface) to the image plane I is shown. In the lens data, the first column m indicates the order (surface number) of the lens surfaces from the object side along the light traveling direction, the second column r indicates the curvature radius of each optical surface, and the third column d. Indicates the distance (surface distance) on the optical axis from each optical surface to the next optical surface, and the fourth column nd and the fifth column νd indicate the refractive index and Abbe number for the d-line (λ = 587.6 nm), respectively. ing. The surface numbers 1 to 26 shown in Table 1 correspond to the numbers 1 to 26 shown in FIG. A curvature radius of 0.0000 indicates a plane on the lens surface and an aperture on the aperture stop S. Further, the refractive index of air of 1.0000 is omitted. The lens group focal length indicates the surface number and focal length of the start surface of each of the first to third lens groups G1 to G3. Here, “mm” is generally used for the focal length, the radius of curvature, the surface interval, and other length units listed in all the following specifications, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1)
[Overall specifications]
f = 32.0
FNO = 1.24
2ω = 29.68
Y = 8.35
TL = 66.83
Bf = 17.9

[Lens data]
m r d nd νd
1 33.7350 4.20 1.60311 60.69
2 86.5367 0.10
3 19.4001 4.00 1.83400 37.18
4 16.1565 2.80
5 23.6229 2.00 1.68893 31.16
6 16.8873 (d6)
7 26.0057 3.00 1.83481 42.73
8 4725.1783 1.60
9 0.0000 4.40 Aperture stop S
10 -21.5624 1.20 1.71736 29.57
11 21.3638 3.40
12 -29.6398 3.20 1.88300 40.66
13 -25.7345 0.10
14 39.0173 5.40 1.77250 49.62
15 -24.7388 (d15)
16 86.3934 2.80 1.72916 54.61
17 -42.0234 1.00 1.68893 31.16
18 15.3910 1.00
19 17.8648 3.50 1.83400 37.18
20 257.4921 13.00
21 0.0000 0.50 1.51680 63.88
22 0.0000 1.11
23 0.0000 1.59 1.51680 63.88
24 0.0000 0.30
25 0.0000 2.79 1.51680 63.88
26 0.0000 (Bf)

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 3574.63
Second lens group 7 28.74
Third lens group 16 113.96

  In the first embodiment, the axial air distance d6 between the first lens group G1 and the second lens group G2 and the axial air distance d15 between the second lens group G2 and the third lens group G3 are from infinity. Changes when focusing on short-range objects. Table 2 below shows variable intervals when focusing on infinity and focusing on a short-distance object. In Table 2, D0 indicates the distance from the lens surface (first surface) closest to the object of the photographic lens SL1 to the object. The description of this variable interval is the same in the following embodiments.

(Table 2)
Infinity Short distance D0 ∞ 700.0000
d6 6.40 4.23
d15 0.63 2.80

  Table 3 below shows values corresponding to the respective conditions of the optical system photographing lens SL1 according to the first example. In Table 3, f is the focal length of the entire system, f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, and f3 is the focal length of the third lens group G3. R1 represents the radius of curvature of the lens surface closest to the object side of the second lens group G2, and f21 represents the focal length of the lens closest to the object side of the second lens group G2. The description of the above symbols is the same in the following embodiments.

(Table 3)
r1 = 26.0057
f21 = 29.80
(1) f1 / f = 111.71
(2) f1 / f2 = 124.38
(3) f1 / f3 = 31.37
(4) r1 / f2 = 0.90
(5) f21 / f = 0.93
(6) f21 / f2 = 1.04

  In the conditional expression (4), r1 is the radius of curvature of the seventh surface, and f21 in the conditional expressions (5) and (6) is the focal length of the positive meniscus lens L21. Thus, the photographic lens SL1 according to the first example satisfies all the conditional expressions (1) to (6).

  FIG. 2 shows spherical aberration, astigmatism, distortion, lateral chromatic aberration, and coma aberration in the infinite focus state and the short distance object focus state (D0 = 700 mm) of the photographing lens SL1 according to the first embodiment. The aberration diagrams of are shown. In each aberration diagram, FNO is the F number, NA is the numerical aperture, Y is the image height with respect to the half field angle, d is the d-line (λ = 587.6 nm), and g is the g-line (λ = 435.6 nm). ) Respectively. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Further, the coma aberration diagram shows the aberration with respect to the image height Y. The explanation of these aberration diagrams is the same in the following examples. As is apparent from the respective aberration diagrams shown in FIG. 2, in the photographing lens SL1 according to the first example, various aberrations are satisfactorily corrected in each state from the infinity in-focus state to the short-distance object in-focus state, It can be seen that the imaging performance is excellent.

[Second Embodiment]
FIG. 3 is a diagram illustrating a configuration of the photographic lens SL2 according to the second example. The photographing lens SL2 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, It is comprised. The first lens group G1, in order from the object side, includes a positive meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a negative meniscus lens L13 having a convex surface directed toward the object side. Composed. 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 biconcave lens L22, a positive meniscus lens L23 having a convex surface facing the image side, and a biconvex lens L24. The The third lens group G3 includes, in order from the object side, a cemented negative lens CL31 of a biconvex lens L31 and a biconcave lens L32, and a positive meniscus lens L33 having a convex surface facing the object side.

  Thus, in the photographic lens SL2 according to the second example, the first lens group G1 includes a positive lens, a negative lens, and a negative lens in order from the object side. In the second lens group G2, the most image-side lens has a biconvex shape (biconvex lens L24). The aperture stop S is disposed between the positive meniscus lens L21 and the biconcave lens L22 in the second lens group G2. A filter group FL including a low-pass filter and an infrared cut filter is disposed between the photographing lens SL2 and the image plane I.

  In the photographic lens SL2 according to the second embodiment having such a configuration, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane when focusing from infinity to a short-distance object. The lens group G2 moves in the object direction along the optical axis. The aperture stop S moves together with the second lens group G2 when focusing.

  Table 4 below provides values of specifications of the optical system photographing lens SL2 according to the second example. The surface numbers 1 to 26 shown in Table 4 correspond to the numbers 1 to 26 shown in FIG.

(Table 4)
[Overall specifications]
f = 32.0
FNO = 1.24
2ω = 29.55
Y = 8.35
TL = 67.83
Bf = 17.9

[Lens data]
m r d nd νd
1 31.6963 4.20 1.60311 60.69
2 84.6431 0.10
3 19.1926 4.00 1.83400 37.18
4 15.7501 2.80
5 27.5058 2.00 1.68890 31.16
6 18.0134 (d6)
7 26.3645 3.00 1.88300 40.66
8 6348.2640 1.60
9 0.0000 3.50 Aperture stop S
10 -21.0843 1.20 1.71736 29.57
11 21.4095 3.50
12 -29.5633 3.20 1.83481 42.73
13 -24.3102 0.10
14 38.2013 5.40 1.77250 49.62
15 -25.2095 (d15)
16 108.3578 2.80 1.69680 55.52
17 -31.1138 1.00 1.67270 32.19
18 16.2311 1.00
19 19.4752 3.50 1.83400 37.18
20 640.9531 13.00
21 0.0000 0.50 1.51680 63.88
22 0.0000 1.11
23 0.0000 1.59 1.51680 63.88
24 0.0000 0.30
25 0.0000 2.79 1.51680 63.88
26 0.0000 (Bf)

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 7852.20
Second lens group 7 28.96
Third lens group 16 115.02

  In the second embodiment, the axial air distance d6 between the first lens group G1 and the second lens group G2 and the axial air distance d15 between the second lens group G2 and the third lens group G3 are from infinity. Changes when focusing on short-range objects. Table 5 below shows variable intervals when focusing on infinity and focusing on a short-distance object.

(Table 5)
Infinity Short distance D0 ∞ 700.0000
d6 6.40 4.17
d17 0.63 2.86

  Table 6 below shows values corresponding to the respective conditions of the photographic lens SL2 according to the second example.

(Table 6)
r1 = 26.3645
f21 = 29.98
(1) f1 / f = 245.38
(2) f1 / f2 = 271.40
(3) f1 / f3 = 68.27
(4) r1 / f2 = 0.91
(5) f21 / f = 0.94
(6) f21 / f2 = 1.04

  In the conditional expression (4), r1 is the radius of curvature of the seventh surface, and f21 in the conditional expressions (5) and (6) is the focal length of the positive meniscus lens L21. Thus, the photographic lens SL2 according to the second example satisfies all the conditional expressions (1) to (6).

  FIG. 4 shows spherical aberration, astigmatism, distortion, lateral chromatic aberration, and coma aberration in the infinite focus state and the short distance object focus state (D0 = 700 mm) of the taking lens SL2 according to the second embodiment. The aberration diagrams of are shown. As apparent from the respective aberration diagrams shown in FIG. 4, in the photographing lens SL2 according to the second example, various aberrations are satisfactorily corrected in each state from the infinity in-focus state to the short-distance object in-focus state, It can be seen that the imaging performance is excellent.

[Third embodiment]
FIG. 5 is a diagram illustrating a configuration of the photographic lens SL3 according to the third example. The photographing lens SL3 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, It is comprised. The first lens group G1, in order from the object side, includes a positive meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a negative meniscus lens L13 having a convex surface directed toward the object side. Composed. 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 biconcave lens L22, a positive meniscus lens L23 having a convex surface facing the image side, and a biconvex lens L24. The The third lens group G3 includes, in order from the object side, a cemented negative lens CL31 of a biconvex lens L31 and a biconcave lens L32, and a positive meniscus lens L33 having a convex surface facing the object side.

  Thus, in the photographic lens SL3 according to the third example, the first lens group G1 includes a positive lens, a negative lens, and a negative lens in order from the object side. In the second lens group G2, the most image-side lens has a biconvex shape (biconvex lens L24). The aperture stop S is disposed between the positive meniscus lens L21 and the biconcave lens L22 in the second lens group G2. A filter group FL including a low-pass filter and an infrared cut filter is disposed between the photographing lens SL3 and the image plane I.

  In the photographic lens SL3 according to the third example having such a configuration, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane when focusing from infinity to a close object, and the second lens group G3 is fixed to the image plane. The lens group G2 moves in the object direction along the optical axis. The aperture stop S moves together with the second lens group G2 when focusing.

  Table 7 below lists values of specifications of the photographing lens SL3 according to the third example. The surface numbers 1 to 26 shown in Table 7 correspond to the numbers 1 to 26 shown in FIG.

(Table 7)
[Overall specifications]
f = 32.0
FNO = 1.24
2ω = 28.66
Y = 8.10
TL = 67.23
Bf = 17.9

[Lens data]
m r d nd νd
1 29.3012 4.20 1.60311 60.69
2 77.0249 0.10
3 18.9354 4.00 1.88300 40.66
4 16.0658 2.80
5 24.9943 1.80 1.72825 28.38
6 15.7326 (d6)
7 26.7023 3.00 1.88300 40.66
8 865.1656 2.00
9 0.0000 3.50 Aperture stop S
10 -19.8589 1.20 1.68893 31.16
11 21.0669 3.20
12 -27.8260 3.00 1.83481 42.73
13 -23.3973 0.10
14 36.0097 5.20 1.78800 47.35
15 -25.2095 (d15)
16 440.3747 2.80 1.69680 55.52
17 -25.0487 1.00 1.68893 31.16
18 16.2765 0.80
19 19.4519 3.40 1.83400 37.18
20 -127.8912 13.00
21 0.0000 0.50 1.51680 63.88
22 0.0000 1.11
23 0.0000 1.59 1.51680 63.88
24 0.0000 0.30
25 0.0000 2.79 1.51680 63.88
26 0.0000 (Bf)

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 7615.78
Second lens group 7 28.59
Third lens group 16 95.38

  In the third example, the axial air distance d6 between the first lens group G1 and the second lens group G2 and the axial air distance d15 between the second lens group G2 and the third lens group G3 are from infinity. Changes when focusing on short-range objects. Table 8 below shows variable intervals when focusing on infinity and focusing on a short-distance object.

(Table 8)
Infinity Short distance D0 ∞ 700.0000
d6 6.60 4.33
d17 0.63 2.90

  Table 9 below shows values corresponding to the respective conditions of the photographic lens SL3 according to the third example.

(Table 9)
r1 = 26.7023
f21 = 31.15
(1) f1 / f = 237.99
(2) f1 / f2 = 266.38
(3) f1 / f3 = 79.85
(4) r1 / f2 = 0.93
(5) f21 / f = 0.97
(6) f21 / f2 = 1.09

  In the conditional expression (4), r1 is the radius of curvature of the seventh surface, and f21 in the conditional expressions (5) and (6) is the focal length of the positive meniscus lens L21. As described above, the photographic lens SL3 according to the third example satisfies all the conditional expressions (1) to (6).

  FIG. 6 shows spherical aberration, astigmatism, distortion, lateral chromatic aberration, and coma aberration in the infinite focus state and the short distance object focus state (D0 = 700 mm) of the taking lens SL3 according to the third embodiment. The aberration diagrams of are shown. As is apparent from the respective aberration diagrams shown in FIG. 6, in the photographing lens SL3 according to the third example, various aberrations are satisfactorily corrected in each state from the infinite focus state to the short distance object focus state. It can be seen that the imaging performance is excellent.

[Fourth embodiment]
FIG. 7 is a diagram illustrating a configuration of the photographic lens SL4 according to the fourth example. The photographing lens SL4 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, It is comprised. The first lens group G1, in order from the object side, includes a positive meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a negative meniscus lens L13 having a convex surface directed toward the object side. Composed. 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 biconcave lens L22, a positive meniscus lens L23 having a convex surface facing the image side, and a biconvex lens L24. The The third lens group G3 includes, in order from the object side, a cemented negative lens CL31 of a biconvex lens L31 and a biconcave lens L32, and a positive meniscus lens L33 having a convex surface facing the object side.

  Thus, in the photographic lens SL4 according to the fourth example, the first lens group G1 includes a positive lens, a negative lens, and a negative lens in order from the object side. In the second lens group G2, the most image-side lens has a biconvex shape (biconvex lens L24). The aperture stop S is disposed between the positive meniscus lens L21 and the biconcave lens L22 in the second lens group G2. A filter group FL including a low-pass filter and an infrared cut filter is disposed between the photographing lens SL4 and the image plane I.

  In the photographic lens SL4 according to the fourth embodiment having such a configuration, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane when focusing from infinity to a close object, and the second lens group G3 is fixed to the image plane. The lens group G2 moves in the object direction along the optical axis. The aperture stop S moves together with the second lens group G2 when focusing.

  Table 10 below lists values of specifications of the photographing lens SL4 according to the fourth example. The surface numbers 1 to 26 shown in Table 10 correspond to the numbers 1 to 26 shown in FIG.

(Table 10)
[Overall specifications]
f = 32.0
FNO = 1.24
2ω = 29.59
Y = 8.35
TL = 70.13
Bf = 17.9

[Lens data]
m r d nd νd
1 29.2625 4.00 1.60311 60.69
2 75.2290 0.10
3 21.1759 4.00 1.83400 37.18
4 15.6335 2.80
5 25.3803 3.40 1.68893 31.16
6 19.1390 (d6)
7 26.6070 3.00 1.88300 40.66
8 657.2810 1.60
9 0.0000 3.50 Aperture stop S
10 -24.3424 1.20 1.72825 28.38
11 19.5526 3.20
12 -26.8107 3.20 1.77250 49.62
13 -28.3839 0.10
14 41.1814 5.20 1.88300 40.66
15 -26.5456 (d15)
16 67.7377 4.00 1.69680 55.52
17 -20.9763 1.00 1.68893 31.16
18 15.6839 1.00
19 19.0132 3.50 1.83400 37.18
20 -1109.8435 13.00
21 0.0000 0.50 1.51680 63.88
22 0.0000 1.11
23 0.0000 1.59 1.51680 63.88
24 0.0000 0.30
25 0.0000 2.79 1.51680 63.88
26 0.0000 (Bf)

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 2606.14
Second lens group 7 32.24
Third lens group 16 78.56

  In the fourth example, the axial air distance d6 between the first lens group G1 and the second lens group G2 and the axial air distance d15 between the second lens group G2 and the third lens group G3 are from infinity. Changes when focusing on short-range objects. Table 11 below shows variable intervals when focusing on infinity and focusing on a short-distance object.

(Table 11)
Infinity Short distance D0 ∞ 700.0000
d6 6.80 3.99
d17 0.63 3.44

  Table 12 below shows corresponding values of the conditions of the photographic lens SL4 according to the fourth example.

(Table 12)
r1 = 26.6070
f21 = 31.33
(1) f1 / f = 81.44
(2) f1 / f2 = 80.84
(3) f1 / f3 = 33.17
(4) r1 / f2 = 0.83
(5) f21 / f = 0.98
(6) f21 / f2 = 0.97

  In the conditional expression (4), r1 is the radius of curvature of the seventh surface, and f21 in the conditional expressions (5) and (6) is the focal length of the positive meniscus lens L21. As described above, the photographic lens SL4 according to the fourth example satisfies all the conditional expressions (1) to (6).

  FIG. 8 shows spherical aberration, astigmatism, distortion, lateral chromatic aberration, and coma aberration in the infinite focus state and the short distance object focus state (D0 = 700 mm) of the taking lens SL4 according to the fourth embodiment. The aberration diagrams of are shown. As is apparent from the respective aberration diagrams shown in FIG. 8, in the photographing lens SL4 according to the fourth example, various aberrations are satisfactorily corrected in each state from the infinity in-focus state to the short-distance object in-focus state, It can be seen that the imaging performance is excellent.

SL (SL1 to SL4) Shooting lens G1 First lens group L11 Positive meniscus lens L12, L13 Negative meniscus lens G2 Second lens group L21 Positive meniscus lens L24 Biconvex lens G3 Third lens group S Aperture stop 1 Camera (optical equipment)

Claims (11)

From the object side,
A first lens group having a positive refractive power;
A second lens group having a positive refractive power;
A third lens group having a positive refractive power,
Upon 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,
A photographic lens characterized by satisfying the following conditional expression:
70 <f1 / f <300
However,
f1: Focal length of the first lens group f: Focal length of the entire system when focusing on infinity The photographic lens according to claim 1, wherein the following conditional expression is satisfied.
60 <f1 / f2 <350
However,
f2: Focal length of the second lens group The photographic lens according to claim 1, wherein the following conditional expression is satisfied.
20 <f1 / f3 <90
However,
f3: focal length of the third lens group The photographic lens according to claim 1, wherein the following conditional expression is satisfied.
0.70 <r1 / f2 <1.05
However,
r1: radius of curvature of the lens surface closest to the object side of the second lens group f2: focal length of the second lens group The photographic lens according to claim 1, wherein the following conditional expression is satisfied.
0.80 <f21 / f <1.20
However,
f21: Focal length of the lens disposed closest to the object side in the second lens group The photographic lens according to claim 1, wherein the following conditional expression is satisfied.
0.80 <f21 / f2 <1.50
However,
f21: Focal length of the lens disposed closest to the object side of the second lens group f2: Focal length of the second lens group   The photographic lens according to claim 1, wherein the first lens group includes a positive lens, a negative lens, and a negative lens in order from the object side.   The photographic lens according to claim 1, wherein the most image-side lens of the second lens group has a biconvex shape.   The photographic lens according to claim 1, further comprising an aperture stop in the second lens group.   An optical apparatus comprising the photographing lens according to claim 1. A method of manufacturing a photographic lens having, in order from the object side, a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. And
In focusing, the first lens group and the third lens group are fixed with respect to the image plane, and the second lens group is arranged to move along the optical axis,
A method for manufacturing a photographic lens, characterized by being arranged to satisfy the following conditional expression:
70 <f1 / f <300
However,
f1: Focal length of the first lens group f: Focal length of the entire system when focusing on infinity

Images