JP2015172611A - Imaging optical system and imaging apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging optical system having a wide angle of view, a large aperture ratio, and a long back-focus, which is capable of performing focusing quickly, and achieving high optical performance.SOLUTION: The imaging optical system includes, in order from the object side to the image side: a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power, and when focusing is performed from an object at a long distance to an object at a short distance, the second lens group moves to the image side. The first lens group comprises five or less lenses including a negative lens Ln whose concave surface is directed toward the object side and a positive lens Lp arranged on the image side of the negative lens Ln. The curvature radius R1 of the object side lens surface of the positive lens Lp, and the curvature radius R2 of the image side lens surface of the positive lens Lp are set appropriately.

Description

  The present invention relates to a photographing optical system and an image pickup apparatus having the same, and is suitable as a photographing optical system such as a digital still camera, a digital video camera, a TV camera, a surveillance camera, and a silver salt film camera.

  An imaging optical system used in an imaging apparatus such as a single-lens reflex camera is required to have a wide angle of view, a large aperture ratio, a back focus of a predetermined length, and high-speed focusing. . As a focusing method, an inner focus method is known in which focusing is performed by moving a lens unit disposed on the image side relative to a lens unit disposed on the most object side of the photographing optical system. In the inner focus method, it is easy to reduce the size and weight of the lens group that is moved for focusing, so it is easy to realize high-speed focusing and downsizing of the drive motor.

  Patent Document 1 has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power in order from the object side to the image side. An imaging optical system for moving a lens group is disclosed.

JP 2000-284171 A

  If the wide angle of view and the large aperture are achieved in the inner focus type photographing optical system, variations in various aberrations such as spherical aberration, coma aberration, and distortion aberration become large during focusing, making it difficult to correct aberrations. For example, in order to satisfactorily correct aberrations in a photographing optical system having a photographing field angle of about 40 ° to 60 ° and a small F number, a certain number of lenses is required.

  On the other hand, in order to reduce the size and weight of the photographic optical system, it is important to reduce the number of lenses in the entire system, particularly the number of lenses in the lens group arranged on the object side where the effective diameter of the lens increases. . For this reason, in order to correct aberrations satisfactorily while reducing the size of the entire system, it is important to appropriately determine the lens configuration of the entire system. In a photographing optical system having a wide angle of view and a long back focus, fluctuations in distortion tend to increase when the focusing lens group is moved. In order to reduce the variation in distortion at this time, it is preferable to dispose a lens having a negative refractive power with a concave surface facing the object side in the first lens group.

  However, if a lens having a negative refractive power with a concave surface facing the object side is simply disposed, light rays diverge by the lens, so that a higher-order spherical aberration is greatly generated when the aperture ratio is increased.

  An object of the present invention is to provide a photographing optical system having a wide angle of view, a large aperture, a long back focus, high-speed focusing, and high optical performance.

The photographing optical system of the present invention is composed of a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power in order from the object side to the image side.
In the photographing optical system in which the second lens group moves to the image side during focusing from a long distance object to a short distance object,
The first lens group includes five or less lenses including a negative lens Ln having a concave surface facing the object side and a positive lens Lp disposed on the image side of the negative lens Ln.
When the radius of curvature of the object side lens surface of the positive lens Lp is R1, and the radius of curvature of the image side lens surface of the positive lens Lp is R2,
0.04 <(R1 + R2) / (R1-R2) <2.00
It satisfies the following conditional expression.

  According to the present invention, a photographing optical system having a wide angle of view, a large aperture, a long back focus, high-speed focusing, and high optical performance can be obtained.

Sectional view of the lens in Example 1 of the present invention (A), (B) Aberration diagrams in Example 1 of the present invention (object at infinity and object at close range) Lens sectional drawing in Example 2 of the present invention (A), (B) Aberration diagrams in Example 2 of the present invention (object at infinity and object at close range) Lens sectional drawing in Example 3 of the present invention (A), (B) Aberration diagrams in Example 3 of the present invention (an object at infinity and an object at close range) Lens cross-sectional view in Example 4 of the present invention (A), (B) Aberration diagrams in Example 4 of the present invention (object at infinity and object at close range) Lens sectional view in Example 5 of the present invention (A), (B) Aberration diagrams in Example 5 of the present invention (object at infinity and object at close range) Schematic diagram of main parts of an imaging apparatus of the present invention

  The photographic optical system according to each embodiment of the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, and a third lens having a positive refractive power. It has a lens group. Then, during focusing from a long distance object to a short distance object, the second lens group moves to the image side.

  FIG. 1 is a lens cross-sectional view when focusing on an object at infinity of the photographing optical system of Embodiment 1 of the present invention. FIGS. 2A and 2B are longitudinal aberration diagrams when focusing on an object at infinity and an object at a close distance (450 mm) of the photographing optical system of Example 1. FIGS. The first embodiment is a photographing optical system having a photographing field angle of 40.92 degrees and an F number of about 1.45.

  FIG. 3 is a lens cross-sectional view when focusing on an object at infinity of the photographing optical system according to the second embodiment of the present invention. 4A and 4B are longitudinal aberration diagrams when focusing on an object at infinity and a close object (300 mm) of the photographing optical system of Example 2. FIG. The second embodiment is a photographing optical system having a photographing field angle of 46.8 degrees and an F number of about 1.45.

  FIG. 5 is a lens cross-sectional view when focusing on an object at infinity of the photographing optical system according to the third embodiment of the present invention. 6A and 6B are longitudinal aberration diagrams when focusing on an object at infinity and an object at a close distance (450 mm) of the photographing optical system of Example 3. FIG. The third embodiment is a photographing optical system having a photographing field angle of 51.14 degrees and an F number of about 1.45.

  FIG. 7 is a lens cross-sectional view when focusing on an object at infinity of the photographing optical system according to Example 4 of the present invention. FIGS. 8A and 8B are longitudinal aberration diagrams when focusing on an object at infinity and a close object (450 mm) in the photographing optical system of Example 4. FIGS. The fourth embodiment is a photographing optical system having a photographing field angle of 39.7 degrees and an F number of about 1.45.

  FIG. 9 is a lens cross-sectional view when focusing on an object at infinity of the photographing optical system according to Example 5 of the present invention. FIGS. 10A and 10B are longitudinal aberration diagrams when focusing on an object at infinity and an object at a close distance (450 mm) of the photographing optical system of Example 5. FIGS. The fifth embodiment is a photographing optical system having a photographing field angle of 62.18 degrees and an F number of about 1.45.

  The numerical value of the close object is a numerical value when a numerical example described later is expressed in mm. FIG. 11 is a schematic diagram of a main part of the imaging apparatus of the present invention. In the lens cross-sectional view, the left side is the object side (front, enlargement side), and the right side is the image side (rear, reduction side). OL is a photographic optical system, and in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, an aperture stop SP, and a third lens unit having a positive refractive power. It consists of L3. The first lens unit L1 includes a negative lens Ln having a concave surface directed toward the object side, and a positive lens Lp disposed on the image side of the negative lens Ln.

  IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, the image plane corresponds to an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor. When used for a silver salt film camera, the image plane corresponds to a film plane. In the spherical aberration diagram, d represents the d-line, and g represents the g-line. In the astigmatism diagram, ΔM represents the d-line meridional image plane, and ΔS represents the d-line sagittal image plane. Distortion is represented by d-line. The lateral chromatic aberration is shown for the g-line. Fno is an F number, and ω is a half angle of view (degrees).

  In each embodiment, when focusing from a long distance object (an object at infinity) to a short distance object, an inner focus method is used in which the second lens unit L2 is moved to the image side. The first lens unit L1 having a positive refractive power converges the photographic light flux and makes it incident on the second lens unit L2. Therefore, the effective diameter of the second lens unit L2 can be reduced, and the focusing lens unit can be reduced in size. It has become. In a wide-angle photographic optical system with a photographic field angle of about 40 ° to 60 °, it is difficult to increase the back focus because the focal length is relatively short. Further, when the aperture is increased, the thickness of each lens increases, and it becomes more difficult to lengthen the back focus.

  Therefore, in each embodiment, the third lens unit L3 has a retrofocus lens configuration so that the back focus is increased.

  In the photographic optical system of each embodiment, positive distortion occurs in the first lens unit L1 having a positive refractive power. The distortion at this time is reduced by the negative distortion generated in the second lens unit L2 having a negative refractive power and the third lens unit L3 having a positive refractive power. During focusing from a long distance object to a short distance object, the second lens unit L2 is moved to the image side. When the light beam passing through the end of the entrance pupil of the photographing optical system is a marginal light beam, the incident height of the marginal light beam in the second lens unit L2 is lower in the in-focus state of the short-distance object than in the in-focus state of the long-distance object. It has become.

  Therefore, in the state in which the object is focused on a short-distance object, the positive distortion generated from the first lens unit L1 and the negative distortion generated from the third lens unit L3 are almost the same, whereas the second distortion is not changed. Negative distortion generated from the lens unit L2 is greatly reduced. Therefore, the effect of reducing the positive distortion generated from the first lens unit L1 by focusing is reduced, and the fluctuation of distortion is increased.

  Therefore, in each embodiment, a negative lens Ln having a concave surface facing the object side is arranged in the first lens unit L1, and a positive lens Lp is arranged on the image side. By disposing the negative lens Ln adjacent to the object side of the positive lens Lp, it is possible to reduce the positive distortion generated by the positive lens Lp, and it is possible to reduce the fluctuation of distortion due to focusing. Further, in order to reduce higher-order aberrations such as spherical aberration in the positive lens Lp on which the divergent light beam emitted from the negative lens Ln is incident, the shape of the positive lens Lp is such that the radius of curvature of the lens surface on the object side is increased. Yes.

In each embodiment, the radius of curvature of the lens surface on the object side of the positive lens Lp is R1, and the radius of curvature of the lens surface on the image side of the positive lens Lp is R2. At this time,
0.04 <(R1 + R2) / (R1-R2) <2.00 (1)
The following conditional expression is satisfied.

  Conditional expression (1) relates to the lens shape of the positive lens Lp and is intended to reduce the occurrence of higher-order aberrations such as spherical aberration in the positive lens Lp on which the divergent light beam emitted from the negative lens Ln is incident. If the lower limit of conditional expression (1) is not reached, the angle at which the divergent light beam from the negative lens Ln enters the positive lens Lp increases, and spherical aberration, coma aberration, etc. increase when the aperture is increased. Is difficult to correct.

  On the other hand, if the upper limit of conditional expression (1) is exceeded, the radius of curvature of the image-side lens surface of the positive lens Lp will be small, and many high-order aberrations such as spherical aberration will occur, and these differences can be corrected. It becomes difficult. Preferably, the range of conditional expression (1) is as follows.

0.08 <(R1 + R2) / (R1-R2) <1.80 (1a)
More preferably, the range of conditional expression (1) should be as follows.

0.09 <(R1 + R2) / (R1-R2) <1.40 (1b)
In each embodiment, the number of constituent lenses of the first lens unit L1 is set to five or less in order to satisfactorily correct various aberrations while reducing the size of the photographing optical system. If the number of constituent lenses of the first lens unit L1 is further increased, it becomes difficult to reduce the size and weight of the photographing optical system. In addition, when the number of constituent lenses of the first lens unit L1 is two or less, it is difficult to satisfactorily correct aberrations. More preferably, the number of constituent lenses of the first lens unit L1 is 3 or more and 5 or less.

  By configuring as described above, the second lens group for focusing has a wide field angle of about 40 ° to 60 °, an F-number of about 1.4, a large aperture ratio, a long back focus, and a focus. A small photographic optical system with small aberration fluctuation when L2 is moved is obtained. In each embodiment, it is more preferable to satisfy one or more of the following conditional expressions.

  The focal length of the first lens unit L1 is f1, the focal length of the second lens unit L2 is f2, the focal length of the third lens unit is f3, the focal length of the photographing optical system is f, and the positive lens disposed in the third lens unit. Let fp be the focal length of the positive lens having the strongest refractive power among the lenses. Also, let Rn be the radius of curvature of the object-side lens surface of the negative lens disposed on the object side of the third lens unit L3. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.70 <| f2 / f | <2.50 (2)
0.50 <f1 / f <1.50 (3)
0.75 <f3 / f <1.50 (4)
0.30 <fp / f <1.00 (5)
0.25 <| Rn / f3 | <0.60 (6)

  Conditional expression (2) relates to the refractive power of the second lens unit L2 for focusing, and is mainly for reducing fluctuations in distortion associated with focusing while increasing the diameter. If the negative refractive power of the second lens unit L2 increases beyond the lower limit of conditional expression (2) (the absolute value of the negative refractive power increases), the variation in aberrations during focusing increases. When the negative refracting power of the second lens unit L2 becomes smaller than the upper limit of the conditional expression (2) (the absolute value of the negative refracting power becomes smaller), the amount of feeding for focusing becomes longer, so the photographing optical system Will become larger. Preferably, the numerical range of conditional expression (2) should be as follows.

0.80 <| f2 / f | <2.30 (2a)
More preferably, the numerical range of conditional expression (2a) should be as follows.

0.90 <| f2 / f | <2.00 (2b)
Conditional expression (3) relates to the refractive power of the first lens unit L1, and is intended to reduce the size of the photographing optical system while maintaining good optical performance. When the lower limit of conditional expression (3) is exceeded and the positive refractive power of the first lens group increases, spherical aberration and coma aberration occur more than the first lens group L1, and the image quality deteriorates.

  If the refractive power of the first lens unit L1 decreases beyond the upper limit of conditional expression (3), the total lens length (distance from the first lens surface to the image plane) increases, making it difficult to downsize the entire system. Become. In particular, the converging action of the light beam incident on the second lens unit L2 is reduced, and the second lens unit L2 is increased in size. Preferably, the numerical range of conditional expression (3) should be as follows.

0.60 <f1 / f <1.30 (3a)
More preferably, the range of conditional expression (3a) should be as follows.

0.70 <f1 / f <1.10 (3b)
Further, when the focal length of the third lens group is f3 and the focal length of the photographing optical system is f, the following conditional expression is satisfied.

  Conditional expression (4) relates to the refractive power of the third lens group. The imaging optical system of each embodiment includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, and a third lens group having a positive refractive power. Have. With this optical arrangement, off-axis aberrations, particularly distortion and lateral chromatic aberration, generated in the first lens group are canceled out by the third lens group. If the range of the conditional expression (4) is exceeded, the effect of canceling off-axis aberrations of the first lens group and the third lens group is insufficient, and distortion and lateral chromatic aberration are reduced. Preferably, it is desirable to set the range of conditional expression (4) as follows.

0.80 <f3 / f <1.40 (4a)
Conditional expression (5) is a conditional expression for ensuring high optical performance and a long back focus. The imaging optical system of each embodiment has a retrofocus lens configuration in which the positive lens having the strongest refractive power among the positive lenses constituting the third lens group is arranged on the image side of the third lens group. Ensures long back focus.

  If the refractive power of the positive lens arranged on the image side of the third lens group is increased beyond the lower limit of conditional expression (5), the back focus can be increased, but the Petzval sum is increased and the curvature of field is increased. descend. If the refractive power of the positive lens arranged on the image side of the third lens group is reduced beyond the upper limit of conditional expression (5), it is difficult to ensure the back focus. It is preferable to set the range of conditional expression (5) as follows.

0.35 <fp / f <0.95 (5a)
Conditional expression (6) relates to the refractive power of the concave lens surface on the object side of the negative lens disposed on the object side of the third lens group, and is for reducing aberration fluctuations due to focusing. If the lower limit of conditional expression (6) is exceeded and the refractive power of the concave surface is increased, high-order spherical aberration and coma aberration generated on this surface are greatly generated and image quality is degraded.

  If the refractive power of the concave surface decreases beyond the upper limit of conditional expression (6), the aberration correction share of the second lens group increases, and the variation in focusing aberration increases. Further, the Petzval sum is increased and the field curvature is reduced. Furthermore, since the action of lengthening the back focus by the retrofocus type configuration of the third lens group is reduced, the back focus cannot be lengthened. Preferably, it is desirable to set the range of conditional expression (6) as follows.

0.30 <| Rn / f3 | <0.50 (6a)
Each embodiment will be described below.

[Example 1]
With reference to FIG. 1, the lens configuration of the photographing optical system of Example 1 of the present invention will be described. The first exemplary embodiment includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and a third lens unit L3 having a positive refractive power. An aperture stop SP is provided between the second lens unit L2 and the third lens unit L3. During focusing from a long-distance object to a short-distance object, the second lens unit L2 moves to the image side as indicated by an arrow.

  Next, the configuration of each lens group will be described. Hereinafter, it is assumed that the lenses of each lens group are arranged in order from the object side to the image side. The first lens unit L1 includes a meniscus negative lens Ln having a concave surface facing the object side, a biconvex positive lens Lp, a meniscus positive lens having an aspheric surface on the object side and a convex surface facing the image side. The lens is composed of a biconvex positive lens.

  By arranging the negative lens Ln and the positive lens Lp adjacent to each other, higher-order aberrations are effectively corrected. The second lens unit L2 is composed of two independent lenses: a biconvex positive lens, an image-side lens surface that is aspherical, and a biconcave negative lens. This aspherical shape corrects coma well. The third lens unit L3 includes a cemented lens obtained by cementing a biconvex positive lens and a biconcave negative lens, a biconcave negative lens having a curvature that is stronger on the object side than the image side, and a biconvex positive lens. Are cemented lenses. Further, the image-side lens surface is an aspherical surface and is constituted by a biconvex positive lens.

  This aspherical shape makes it possible to correct off-axis aberrations satisfactorily. As can be seen from the aberration diagrams, there are few fluctuations in aberrations during focusing, especially distortion fluctuations, and there are few high-order aberrations in spherical aberration, and good optical performance is obtained.

[Example 2]
Hereinafter, the lens configuration of the photographing optical system according to the second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the number of lens groups, the refractive power of each lens group, and the movement of the lens groups during focusing are the same as those in the first embodiment.

  Next, the configuration of the lens group will be described. Hereinafter, it is assumed that each lens group is arranged in order from the object side to the image side. The first lens unit L1 includes a meniscus negative lens Ln having a concave surface directed toward the object side, a positive lens Lp having an aspherical and biconvex lens surface on the object side, and a biconvex positive lens. . The second lens unit L2 includes two independent lenses, a meniscus positive lens having a convex surface facing the object side, and a meniscus negative lens having an aspheric surface on the image side and a concave surface facing the image side. ing.

  This aspherical shape corrects coma well. The third lens unit L3 is the same as that in the first embodiment. As in Example 1, there are few aberration fluctuations during focusing, particularly distortion fluctuations, and there are few high-order aberrations with respect to spherical aberration, and good optical performance is obtained.

[Example 3]
Hereinafter, the lens configuration of the photographing optical system according to the third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the number of lens groups, the refractive power of each lens group, and the movement of the lens groups during focusing are the same as those in the first embodiment.

  Next, the configuration of each lens group will be described. The first lens group L1 and the second lens group L2 are the same as those in the second embodiment. The third lens unit L3 is the same as that in the first embodiment. As in Example 1, there are few aberration fluctuations during focusing, particularly distortion fluctuations, and there are few high-order aberrations with respect to spherical aberration, and good optical performance is obtained.

[Example 4]
Hereinafter, the lens configuration of the photographing optical system according to Example 4 of the present invention will be described with reference to FIG. In the fourth embodiment, the number of lens groups, the refractive power of each lens group, and the movement of the lens groups during focusing are the same as those in the first embodiment.

  Next, the configuration of each lens group will be described. The first lens unit L1 is the same as that in the second embodiment. The second lens group L2 and the third lens group L3 are the same as those in the first embodiment. As in Example 1, there are few aberration fluctuations during focusing, particularly distortion fluctuations, and there are few high-order aberrations with respect to spherical aberration, and good optical performance is obtained.

[Example 5]
Hereinafter, the lens configuration of the photographing optical system according to Example 5 of the present invention will be described with reference to FIG. In the fifth embodiment, the number of lens groups, the refractive power of each lens group, and the movement of the lens groups during focusing are the same as those in the first embodiment.

  Next, the configuration of each lens group will be described. Hereinafter, it is assumed that each lens group is arranged in order from the object side to the image side. The first lens unit L1 includes a meniscus negative lens having a convex surface facing the object side, a meniscus positive lens having a concave surface on the object side, a meniscus negative lens Ln having a concave surface on the object side, and an aspheric surface on the object side. And is composed of a biconvex positive lens Lp. Further, it is constituted by a biconvex positive lens.

  The second lens unit L2 includes a cemented lens in which a biconvex positive lens and an image-side lens surface are aspherical and a biconcave negative lens are cemented. This aspherical shape corrects coma well. The third lens unit L3 is the same as that in the first embodiment. As in the first embodiment, there are few aberration fluctuations during focusing, particularly distortion fluctuations, and there are few high-order aberrations with respect to spherical aberration, and good optical performance is obtained.

  Next, an embodiment in which the optical system shown in Embodiments 1 to 5 is applied to a photographing apparatus such as a single-lens reflex camera will be described with reference to FIG. FIG. 11 is a schematic diagram of a single-lens reflex camera. In FIG. 11, reference numeral 10 denotes an interchangeable lens having the photographing optical system 1 of Examples 1 to 5. The photographing optical system 1 is held by a lens barrel 2 that is a holding member. Reference numeral 20 denotes a camera body, which includes a quick return mirror 3 that reflects a light beam from the photographing optical system 1 upward and a focusing screen 4 that is disposed at an image forming position of the photographing optical system 1. Further, it is constituted by a penta roof prism 5 for converting an inverted image formed on the focusing screen 4 into an erect image, an eyepiece 6 for observing the erect image, and the like.

  Reference numeral 7 denotes an imaging surface such as a photoelectric conversion element that receives a subject image. At the time of shooting, the quick return mirror 3 is retracted from the optical path, and an image is formed on the imaging surface 7 by the shooting optical system 1.

  In this way, by applying the imaging optical system of the present invention to an imaging apparatus such as a single-lens reflex camera interchangeable lens, a wide angle of view with an angle of view of about 40 ° to 60 ° and an F-number of about 1.4 is large. An inner focus type imaging device can be realized. The present invention can be similarly applied to a camera without a quick return mirror.

  Next, Numerical Examples 1 to 5 corresponding to Embodiments 1 to 5 of the photographing optical system of the present invention will be shown. In the numerical examples, i indicates a surface number counted from the object side. In the order from the object side, ri is the radius of curvature of the i-th lens surface, di is the i-th lens thickness or air spacing, and ndi and νdi are the refractive index and Abbe number of the d-line of the i-th lens material. is there. The place where the interval is variable is a value when the object distance changes.

The aspherical shape is such that the traveling direction of light is positive, x is the amount of displacement from the surface vertex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, and r is the paraxial radius of curvature. , K is a conic constant, and A4, A6, A8, A10, and A12 are aspheric coefficients,
x = (h ² / r) / [1+ {1− (1 + K) × (h / r) ² } ^1/2 ] + A4 × h ⁴ + A6 × h ⁶ + A8 × h ⁸ + A10 × h ¹⁰ + A12 × h ¹²
It is expressed by the following formula. The numerical value “e ± XX” means “× 10 ^{± XX} ”. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

Numerical example 1
Unit mm

Surface data surface number rd nd νd Effective diameter
1 -50.254 2.50 1.92286 20.9 43.35
2 -95.060 0.21 43.93
3 201.609 5.03 1.85400 40.4 43.11
4 -163.764 0.93 43.34
5 * -1869.670 2.51 1.90270 31.0 43.25
6 -233.276 0.15 43.41
7 75.181 8.26 1.64000 60.1 43.32
8 -74.579 (variable) 42.84
9 110.155 5.62 1.92286 20.9 38.16
10 -338.943 0.44 35.97
11 -195.318 1.76 1.74330 49.3 35.81
12 * 30.222 (variable) 31.12
13 (Aperture) ∞ 0.10 28.78
14 148.200 6.04 1.88300 40.8 28.56
15 -25.216 4.66 1.69895 30.1 28.33
16 37.970 7.29 23.58
17 -17.577 2.00 1.73800 32.3 23.29
18 55.235 9.08 1.77250 49.6 33.62
19 -30.680 0.10 34.93
20 108.441 9.35 1.76802 49.2 44.86
21 * -40.414 38.23 45.25
Image plane ∞

Aspheric data 5th surface
K = 0.00000e + 000 A 4 = -2.39429e-006 A 6 = 5.81878e-010
A 8 = -1.81921e-012 A10 = 1.31469e-015

12th page
K = 0.00000e + 000 A 4 = 7.43317e-007 A 6 = 8.71318e-009
A 8 = -3.06680e-011 A10 = 5.05093e-014

21st page
K = 0.00000e + 000 A 4 = 3.22879e-006 A 6 = -3.69434e-010
A 8 = 2.74844e-012 A10 = -1.67092e-015

Various data

Focal length 57.99
F number 1.45
Half angle of view (degrees) 20.46
Statue height 21.64
Total lens length 117.64
BF 38.23
Object infinity Close object 450mm
d 8 0.32 8.76
d12 13.06 4.62

Entrance pupil position 39.33
Exit pupil position -90.08
Front principal point position 71.11
Rear principal point position -19.75

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
L1 1 45.64 19.59 9.65 -1.60
L2 9 -61.16 7.82 6.88 2.25
L3 13 49.39 38.61 33.47 13.80

Single lens Data lens Start surface Focal length
1 1 -118.71
2 3 106.49
3 5 295.04
4 7 59.79
5 9 90.63
6 11 -35.09
7 14 24.81
8 15 -21.04
9 17 -17.86
10 18 26.77
11 20 39.41

Numerical example 2
Unit mm
Surface data surface number rd nd νd Effective diameter
1 -47.040 4.46 1.92286 20.9 41.41
2 -98.783 1.13 42.06
3 * 875.642 3.15 1.90270 31.0 41.35
4 -90.250 0.10 41.30
5 63.573 7.06 1.64000 60.1 38.34
6 -71.298 (variable) 38.03
7 67.062 4.56 1.92286 20.9 34.09
8 222.325 0.65 32.17
9 2204.106 1.00 1.74330 49.3 32.02
10 * 28.684 (variable) 28.90
11 (Aperture) ∞ 0.10 26.47
12 89.328 5.58 1.88300 40.8 26.19
13 -24.988 1.00 1.69895 30.1 25.91
14 32.215 7.74 22.75
15 -15.860 1.00 1.73800 32.3 22.47
16 55.274 8.09 1.77250 49.6 30.39
17 -30.618 0.10 32.28
18 130.414 9.75 1.76802 49.2 41.96
19 * -30.667 38.00 42.50
Image plane ∞

Aspheric data 3rd surface
K = 0.00000e + 000 A 4 = -2.64999e-006 A 6 = -1.96470e-010
A 8 = 1.04264e-012 A10 = -1.56044e-015

10th page
K = 0.00000e + 000 A 4 = 1.22166e-006 A 6 = -5.40431e-009
A 8 = 4.56519e-011 A10 = -1.08047e-013

19th page
K = 0.00000e + 000 A 4 = 5.77530e-006 A 6 = 1.68886e-009
A 8 = 3.83603e-012 A10 = 6.04991e-016

Various data

Focal length 50.00
F number 1.45
Half angle of view (degrees) 23.40
Statue height 21.64
Total lens length 106.85
BF 38.00

Object infinity Close object 450mm
d 6 0.32 8.74
d10 13.06 4.63

Entrance pupil position 32.39
Exit pupil position -76.16
Front principal point position 60.49
Rear principal point position -12.00

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
L1 1 45.75 15.90 9.48 0.74
L2 7 -68.09 6.20 6.95 3.04
L3 11 45.24 33.37 30.09 13.73

Single lens Data lens Start surface Focal length
1 1 -101.51
2 3 90.78
3 5 53.61
4 7 102.61
5 9 -39.11
6 12 22.63
7 13 -19.99
8 15 -16.60
9 16 26.60
10 18 33.20

Unit mm

Numerical Example 3
Surface data surface number rd nd νd Effective diameter
1 -42.981 5.34 1.92286 20.9 37.95
2 -68.390 0.10 38.42
3 * -1522.722 2.37 1.90270 31.0 37.37
4 -96.296 0.10 37.23
5 68.684 5.30 1.64000 60.1 34.42
6 -69.940 (variable) 34.06
7 62.664 2.15 1.92286 20.9 31.10
8 143.293 0.39 30.51
9 220.766 1.00 1.74330 49.3 30.41
10 * 30.898 (variable) 28.05
11 (Aperture) ∞ 0.10 25.47
12 117.847 5.26 1.88300 40.8 25.26
13 -23.632 1.00 1.69895 30.1 25.01
14 31.205 7.83 22.16
15 -14.959 1.00 1.73800 32.3 21.95
16 66.269 8.04 1.77250 49.6 30.34
17 -26.643 0.10 31.84
18 128.701 9.99 1.76802 49.2 42.70
19 * -31.040 38.00 43.23
Image plane ∞

Aspheric data 3rd surface
K = 0.00000e + 000 A 4 = -2.83682e-006 A 6 = -3.27329e-010
A 8 = 4.06440e-012 A10 = -6.10390e-015

10th page
K = 0.00000e + 000 A 4 = 1.78612e-006 A 6 = 3.31697e-010
A 8 = 2.63907e-011 A10 = -5.81325e-014

19th page
K = 0.00000e + 000 A 4 = 5.59608e-006 A 6 = 1.72914e-009
A 8 = 2.54516e-012 A10 = 1.59027e-015

Focal length 45.21
F number 1.45
Half angle of view (degrees) 25.57
Statue height 21.64
Total lens length 101.44
BF 38.00

Object infinity Close object 450mm
d 6 0.32 9.65
d10 13.06 3.74

Entrance pupil position 26.20
Exit pupil position -85.31
Front principal point position 54.83
Rear principal point position -7.21

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
L1 1 46.24 13.20 8.19 1.41
L2 7 -85.27 3.54 4.45 2.25
L3 11 42.86 33.32 30.12 15.98

Single lens Data lens Start surface Focal length
1 1 -139.42
2 3 113.79
3 5 54.96
4 7 119.15
5 9 -48.44
6 12 22.69
7 13 -19.10
8 15 -16.45
9 16 25.56
10 18 33.47

Numerical Example 4
Unit mm

Surface data surface number rd nd νd Effective diameter
1 -46.591 2.00 1.92286 20.9 44.39
2 -97.429 0.10 45.34
3 * 653.453 4.08 1.90270 31.0 45.17
4 -75.530 2.31 45.21
5 73.930 8.46 1.64000 60.1 45.31
6 -67.200 (variable) 45.10
7 110.112 7.00 1.92286 20.9 39.38
8 -425.202 0.53 36.21
9 -199.361 1.66 1.74330 49.3 36.04
10 * 29.577 (variable) 31.26
11 (Aperture) ∞ 0.10 28.75
12 888.190 5.56 1.88300 40.8 28.69
13 -25.125 1.62 1.69895 30.1 28.52
14 51.240 8.08 25.76
15 -17.688 1.00 1.73800 32.3 25.51
16 62.560 8.33 1.77250 49.6 31.19
17 -27.743 3.95 32.27
18 120.189 8.66 1.76802 49.2 44.85
19 * -44.018 42.17 45.22
Image plane ∞

Aspheric data 3rd surface
K = 0.00000e + 000 A 4 = -2.66236e-006 A 6 = 1.98415e-010
A 8 = -3.00976e-013 A10 = -2.40862e-016

10th page
K = 0.00000e + 000 A 4 = 9.95403e-007 A 6 = 1.57296e-010
A 8 = 8.50330e-012 A10 = -3.55320e-014

19th page
K = 0.00000e + 000 A 4 = 2.51453e-006 A 6 = -5.81872e-010
A 8 = 2.71017e-012 A10 = -1.85250e-015

Various data

Focal length 59.92
F number 1.45
Half angle of view (degrees) 19.85
Statue height 21.64
Total lens length 118.97
BF 42.17
Object infinity Close object 450mm
d 6 0.32 8.75
d10 13.06 4.63

Entrance pupil position 40.61
Exit pupil position -87.93
Front principal point 72.93
Rear principal point position -17.75

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
L1 1 45.78 16.95 8.87 -1.53
L2 7 -58.25 9.19 7.94 2.48
L3 11 49.82 37.30 33.81 17.26

Single lens Data lens Start surface Focal length
1 1 -98.62
2 3 75.20
3 5 56.32
4 7 95.37
5 9 -34.54
6 12 27.75
7 13 -23.91
8 15 -18.59
9 16 25.92
10 18 42.93

Numerical Example 5
Unit mm

Surface data surface number rd nd νd Effective diameter
1 165.189 2.50 1.72916 54.7 51.05
2 35.993 9.16 44.48
3 -196.245 4.40 1.84666 23.9 44.41
4 -61.179 10.52 44.31
5 -30.643 1.90 1.80809 22.8 36.00
6 -402.160 0.20 37.79
7 * 136.859 6.80 1.85400 40.4 38.30
8 -48.859 0.20 38.68
9 109.645 5.82 1.72916 54.7 36.39
10 -51.807 (variable) 36.38
11 187.717 2.40 1.80809 22.8 33.20
12 -185.275 1.50 1.77250 49.6 32.80
13 * 40.799 (variable) 30.43
14 (Aperture) ∞ 0.80 29.46
15 73.090 5.24 1.83481 42.7 29.26
16 -60.391 1.30 1.51742 52.4 28.79
17 29.107 7.48 26.34
18 -23.041 1.50 1.80809 22.8 26.32
19 154.263 6.01 1.88300 40.8 29.75
20 -32.463 0.15 30.51
21 326.570 5.45 1.77250 49.6 33.83
22 * -38.496 38.77 34.41
Image plane ∞

Aspheric data 7th surface
K = 0.00000e + 000 A 4 = -5.21875e-006 A 6 = 5.13741e-009
A 8 = -2.05161e-011 A10 = 4.53067e-014 A12 = -4.02280e-017

Side 13
K = 0.00000e + 000 A 4 = 1.91423e-006 A 6 = 1.73656e-008
A 8 = -8.83548e-011 A10 = 2.38442e-013 A12 = -1.93864e-016

22nd page
K = 0.00000e + 000 A 4 = 2.93084e-006 A 6 = -9.04798e-009
A 8 = 7.06725e-011 A10 = -2.46566e-013 A12 = 3.02917e-016

Focal length 35.88
F number 1.45
Half angle of view (degrees) 31.09
Statue height 21.64
Total lens length 126.92
BF 38.77

Object infinity Close object 450mm
d10 0.90 6.09
d13 13.91 8.72

Entrance pupil position 34.83
Exit pupil position -41.84
Front principal point position 54.74
Rear principal point position 2.90

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
L1 1 38.53 41.50 33.31 13.45
L2 11 -70.14 3.90 2.87 0.67
L3 14 48.17 27.93 23.65 4.63

Single lens Data lens Start surface Focal length
1 1 -63.63
2 3 103.44
3 5 -41.14
4 7 42.88
5 9 49.00
6 11 115.72
7 12 -43.16
8 15 40.33
9 16 -37.77
10 18 -24.71
11 19 30.84
12 21 44.87

L1 First lens group L2 Second lens group L3 Third lens group Ln Negative lens Lp Positive lens SP Aperture stop

Claims (14)

In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power are provided. In the photographing optical system in which the second lens group moves to the image side during focusing,
The first lens group includes five or less lenses including a negative lens Ln having a concave surface facing the object side and a positive lens Lp disposed on the image side of the negative lens Ln.
When the radius of curvature of the object side lens surface of the positive lens Lp is R1, and the radius of curvature of the image side lens surface of the positive lens Lp is R2,
0.04 <(R1 + R2) / (R1-R2) <2.00
An imaging optical system characterized by satisfying the following conditional expression: When the focal length of the second lens group is f2, and the focal length of the photographing optical system is f,
0.70 <| f2 / f | <2.50
The imaging optical system according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the first lens group is f1, and the focal length of the photographing optical system is f,
0.50 <f1 / f <1.50
The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.   4. The photographing optical system according to claim 1, wherein the negative lens Ln is disposed closest to the object side of the first lens group. 5.   5. The photographing optical system according to claim 1, further comprising an aperture stop closer to the image side than the second lens group.   The first lens group includes a negative lens, a positive lens, and a positive lens having a concave surface directed toward the object side in order from the object side to the image side. The taking optical system described in 1.   The first lens group includes a negative lens, a positive lens, a positive lens, and a positive lens having a concave surface directed toward the object side in order from the object side to the image side. The photographing optical system according to claim 1.   The first lens group includes a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens with a concave surface facing the object side in order from the object side to the image side. 6. The photographing optical system according to any one of 5 above.   The photographing optical system according to claim 1, wherein the second lens group includes a positive lens and a negative lens in order from the object side to the image side.   The third lens group includes, in order from the object side to the image side, a cemented lens in which a positive lens and a negative lens are cemented, a cemented lens in which a negative lens and a positive lens are cemented, and a positive lens. The photographing optical system according to any one of claims 1 to 9. When the focal length of the third lens group is f3 and the focal length of the photographing optical system is f,
0.75 <f3 / f <1.50
The imaging optical system according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the positive lens having the strongest refractive power among the positive lenses arranged in the third lens group is fp and the focal length of the photographing optical system is f,
0.30 <fp / f <1.00
The imaging optical system according to claim 1, wherein the following conditional expression is satisfied. When the radius of curvature of the concave lens surface on the object side of the negative lens disposed on the object side of the third lens group is Rn, and the focal length of the third lens group is f3,
0.25 <| Rn / f3 | <0.60
The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.   An imaging apparatus comprising: the photographing optical system according to claim 1; and a photoelectric conversion element that receives an image formed by the photographing optical system.