JP2021124630A - Optical system and imaging apparatus - Google Patents

Abstract

To provide a small optical system which allows downsizing of a focus group, can suppress aberration fluctuation in focusing, and has excellent optical performance, an optical system which allows for providing an imaging apparatus, and an imaging apparatus.SOLUTION: An optical system is constituted by, in sequence from an object side, a first lens group (G1) having positive refractive power, a second lens group (G2) having positive refractive power, and a third lens group (G3) having negative refractive power. In focusing from an infinite distance object to a finite distance object, the first lens group G1 and the third lens group G3 are fixed with respect to an image surface, whilst the second lens group G2 is moved in an optical axis direction, and satisfied a predetermined conditional equation. Additionally, an imaging apparatus includes the optical system and an image pickup device.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical system and an image pickup device, and more particularly to an optical system and an image pickup device suitable for an image pickup device using a solid-state image pickup element (CCD, CMOS, etc.) such as a digital still camera or a digital video camera.

Conventionally, image pickup devices using various solid-state image pickup elements such as video cameras, digital still cameras, single-lens reflex cameras, and mirrorless single-lens cameras have become widespread. With the progress of high performance and miniaturization of these image pickup devices, further high performance and miniaturization of the image pickup lens (optical system) are required. Further, there is a great demand for a large-diameter lens having a small F value.

In addition, many image pickup devices in recent years are equipped with a "live view" function for taking pictures while looking at a liquid crystal display or the like provided on the back of the housing. At the time of live view imaging, autofocus is generally performed by the contrast AF method. In the contrast AF method, the focus group is moved (wobbling) at high speed in the optical axis direction, and the position where the contrast value is the largest is detected as the focus position. Therefore, in order to realize quick autofocus, it is required to reduce the size and weight of the focus group in order to move the focus group at a higher speed. In particular, since the image displayed on the liquid crystal display or the like is delayed during the live view shooting, it is required to realize faster autofocus in order to capture the imaged object at the target timing.

Therefore, in order to reduce the size and weight of the focus group and realize quick autofocus, the first lens group having a positive refractive power and the second lens group having a positive refractive power are arranged in order from the object side. It is composed of a third lens group having a negative refractive power, and a so-called inner focus method is adopted in which focusing is performed by moving the second lens group along the optical axis. In such a configuration, since the second lens group is smaller than the other lens groups, the weight of the focus group can be easily reduced. As an optical system adopting these configurations, for example, Patent Documents 1 to 3 disclose a large-diameter lens having an F value of about 1.2 to 1.4.

JP-A-2017-044887 JP-A-2019-101180 International Publication No. 2017/130571

However, in the optical system disclosed in Patent Document 1, the refractive power of the lens surface on the most object side of the second lens group, which is the focus group, is not optimized, and as a result, the second lens group becomes large and the product There is a problem that the whole becomes large. Further, in the optical system, the arrangement of the refractive power in the second lens group is not appropriate, and it is difficult to make the F value smaller than 1.4. Further, there is also a problem that the aberration fluctuation due to the movement of the second lens group during focusing is large and the optical performance is deteriorated.

On the other hand, in the optical system disclosed in Patent Document 2, the aperture is arranged in the second lens group, and the refractive power arrangement before and after the aperture is made appropriate in the second lens group, thereby realizing a smaller F value while achieving a smaller F value. Aberration fluctuations during focusing are suppressed. However, even in the optical system, the refractive power of the lens surface on the most object side of the second lens group is not optimized. Further, the arrangement of the refractive power with respect to the first lens group and the second lens group is not appropriate. For these reasons, there is a problem that the second lens group is not sufficiently miniaturized and the entire product is also enlarged.

In the optical system disclosed in Patent Document 3, the arrangement of the refractive power with respect to the first lens group and the second lens group is not appropriate, and the first lens group is relatively large. Patent Document 3 discloses an optical system having an F value of about 1.4, but in order to realize an F value of about 1.2 in the optical system, it is inevitable that the first lens group becomes large. .. Further, the lens surface on the most object side of the second lens group is a concave surface, which leads to an increase in the size of the second lens group. For these reasons, there is a problem that the entire product becomes large.

An object of the present invention is to provide an optical system and an image pickup apparatus having a large diameter, capable of rapid autofocus, high optical performance, and a small size.

In order to solve the above problems, the optical system according to the present invention has a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a second lens group having a negative refractive power in order from the object side. It is composed of three lens groups, and when focusing from an infinity object to a finite distance object, the first lens group and the third lens group are fixed to an image plane, and the second lens group is oriented in the optical axis direction. It is characterized in that it is moved to and satisfies the following conditional expression (1).
0.40 ≤ G2Fr / f ≤ 0.70 (1)
However,
G2Fr: Radius of curvature of the lens surface on the most object side of the second lens group f: Focal length at infinity focusing of the optical system

Further, in order to solve the above problems, the image pickup apparatus according to the present invention is characterized by including the above optical system and an image pickup element that converts an optical image formed by the optical system into an electric signal.

According to the present invention, it is possible to provide an optical system and an image pickup apparatus having a large diameter, capable of rapid autofocus, high optical performance, and a small size.

It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 1 of this invention. FIG. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the first embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 1. FIG. It is a spherical aberration diagram, astigmatism diagram, and distortion diagram at the time of the closest focusing of the optical system of the first embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 1. FIG. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 2 of this invention. It is a spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical system of the second embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 2. FIG. It is a spherical aberration diagram, astigmatism diagram, and distortion diagram at the time of closest focusing of the optical system of the second embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 2. FIG. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 3 of this invention. 3 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the third embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 3. FIG. 3 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of closest focusing of the optical system of the third embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 3. FIG. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 4 of this invention. FIG. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the fourth embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 4. FIG. It is a spherical aberration diagram, astigmatism diagram, and distortion diagram at the time of the closest focusing of the optical system of the fourth embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 4. FIG. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 5 of this invention. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the fifth embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 5. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of closest focusing of the optical system of the fifth embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 5. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 6 of this invention. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the sixth embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 6. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of closest focusing of the optical system of the sixth embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 6. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 7 of this invention. FIG. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the seventh embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 7. FIG. FIG. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of closest focusing of the optical system of the seventh embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 7. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 8 of this invention. 8 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the eighth embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 8. 8 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of closest focusing of the optical system of the eighth embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 8. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 9 of this invention. 9 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the ninth embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 9. FIG. 9 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of closest focusing of the optical system of the ninth embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 9. It is a cross-sectional view of the lens at the time of infinity focusing of the optical system of Example 10 of this invention. FIG. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system of the tenth embodiment at infinity focusing. It is a coma aberration diagram at the time of infinity focusing of the optical system of Example 10. FIG. 5 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of closest focusing of the optical system of the tenth embodiment. It is a coma aberration diagram at the time of the closest focusing of the optical system of Example 10.

Hereinafter, embodiments of the optical system and the image pickup apparatus according to the present invention will be described. However, the optical system and the image pickup apparatus described below are one aspect of the optical system and the image pickup apparatus according to the present invention, and the optical system and the image pickup apparatus according to the present invention are not limited to the following aspects.

1. 1. Optical system 1-1. Optical configuration The optical system is composed of 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 negative refractive power in order from the object side. .. In the optical system, an inner focus method is used in which the first lens group and the third lens group are fixed to the image plane and the second lens group is moved in the optical axis direction when focusing from an infinity object to a finite distance object. Is adopted. In such a configuration, since the second lens group is smaller than the other lens groups, the weight of the focus group can be easily reduced.

In the optical system, the lens surface arranged on the object side of the second lens group is focused by forming a lens surface having a shape satisfying the conditional expression (1) described later, that is, a lens surface having a convex shape on the object side. By reducing the size of the second lens group, which is a group, it is possible to reduce the size of the entire product.
Further, in the optical system, by optimizing the arrangement of the refractive power with respect to the first lens group and the second lens group, the first lens group and the second lens group can be miniaturized.

From these facts, it is possible to realize a bright large-diameter lens with an F value of about 1.2, quick autofocus, high optical performance, and a small optical system. ..

In the optical system, the specific lens configuration of each lens group is not limited, but from the viewpoint of further improving the performance of the optical system, the first lens group includes three lenses having a refractive power. It is more preferable to have the above, and it is further preferable to have four or more. From the same viewpoint, it is more preferable to have two or more lenses having a negative refractive power. By adopting such a configuration, it is possible to better correct various aberrations and obtain an optical system having higher optical performance. Further, it is more preferable that the first lens group has two or more lenses having a positive refractive power. By satisfying this configuration, various aberrations can be corrected more satisfactorily, and an optical system having higher optical performance can be obtained.

Further, it is more preferable that the second lens group has two or more lenses having a negative refractive power in order to suppress fluctuations in various aberrations during focusing. In the present specification, the "lens having a refractive power" means a lens having a substantial refractive power, and does not include a translucent member or the like which does not have a substantial refractive power such as a parallel flat plate. do. Hereinafter, various conditional expressions that the optical system is preferably satisfied with will be described.

The position of the diaphragm in the optical system is not particularly limited, but for example, it is preferable to arrange the diaphragm between the lens surface on the most object side and the lens surface on the image side in the second lens group. .. By arranging the diaphragm in the second lens group, the diameter of the diaphragm can be reduced.

In this way, the diaphragm is arranged in the second lens group, and the second lens group is composed of the second A subgroup, the diaphragm, and the second B subgroup in order from the object side, with respect to the second A subgroup and the second B subgroup. By optimizing the arrangement of the refractive power, it is possible to suppress aberration fluctuations during focusing and obtain an optical system with high optical performance. Hereinafter, various conditional expressions that the optical system is preferably satisfied with will be described.

1-2. Conditional expression 1-2-1. Conditional expression (1)
0.40 ≤ G2Fr / f ≤ 0.70 (1)
However,
G2Fr: Radius of curvature of the lens surface on the most object side of the second lens group f: Focal length at infinity focusing of the optical system

The conditional equation (1) is an equation that defines the ratio between the radius of curvature of the lens surface on the most object side of the second lens group and the focal length at infinity focusing of the optical system. By satisfying the conditional expression (1), the refractive power on the lens surface on the most object side of the second lens group is optimized. As a result, the second lens group can be made compact, quick autofocus can be realized, and the entire product can be miniaturized. Further, by satisfying the conditional expression (2) at the same time, an optical system having high optical performance can be obtained.

On the other hand, when the value of the conditional expression (1) is less than the lower limit value, the refractive power on the lens surface on the most object side of the second lens group becomes stronger. In this case, it is advantageous to reduce the size of the focus group and to achieve quick autofocus. However, when the second lens group is eccentric due to a lens manufacturing error, the image plane fluctuation during focusing becomes remarkable. When the image plane fluctuates, a so-called one-sided blur phenomenon may occur in the captured image or the like, for example, the optical performance on the right side is good, but the optical performance on the left side is poor. The smaller the F value of the optical system, the shallower the depth of field. Therefore, when the image plane fluctuates in the large-diameter lens, the one-sided blur phenomenon tends to appear. In particular, when the F value is about 1.2, the one-sided blur phenomenon tends to appear remarkably in such a case. Therefore, it becomes difficult to obtain an optical system having high optical performance. On the other hand, when the value of the conditional expression (1) exceeds the upper limit value and the refractive power on the lens surface on the most object side of the second lens group becomes weak, it becomes difficult to miniaturize the second lens group which is the focus group. , It becomes difficult to realize quick autofocus and miniaturize the entire product.

In order to obtain these effects, the lower limit of the conditional expression (1) is more preferably 0.42, further preferably 0.43, and even more preferably 0.44. The upper limit of the conditional expression (1) is more preferably 0.69, further preferably 0.68, and even more preferably 0.67. When adopting these preferable lower limit values or upper limit values, the equal sign inequality sign (≦) may be replaced with the inequality sign (<) in the conditional expression (1). The same applies to other conditional expressions in principle.

1-2-2. Conditional expression (2)
1.0 ≤ f1 / f2 ≤ 4.0 ... (2)
However,
f1: Focal length of the first lens group f2: Focal length of the second lens group

The conditional expression (2) is an expression that defines the ratio between the focal length of the first lens group and the focal length of the second lens group. By satisfying the conditional equation (2) in the optical system, the arrangement of the refractive power between the first lens group and the second lens group is optimized, and the enlargement of the first lens group and the second lens group is suppressed. The overall size of the product can be reduced. Further, since the second lens group can be configured in a small size, quick autofocus can be realized. Further, by satisfying the conditional expression (1) at the same time, an optical system having high optical performance can be obtained.

On the other hand, when the value of the conditional expression (2) exceeds the upper limit value, the refractive power of the first lens group becomes weak. In this case, since the first lens group becomes large, the entire product also becomes large, which is not preferable. Alternatively, when the value of the conditional expression (2) exceeds the upper limit value, the refractive power of the second lens group, that is, the focus group becomes stronger. In this case, it is advantageous to reduce the size of the focus group and to achieve quick autofocus. However, when the refractive power of the second lens group becomes stronger, when the second lens group is eccentric due to a lens manufacturing error, the image plane fluctuation during focusing becomes remarkable. As a result, when the F value is about 1.2, the one-sided blur phenomenon tends to remarkably appear for the same reason as described above. Therefore, when the value of the conditional expression (2) exceeds the upper limit value due to the strong refractive power of the second lens group, it is difficult to obtain an optical system having high optical performance, which is not preferable.

On the other hand, when the value of the conditional expression (2) is less than the lower limit value, the refractive power of the first lens group becomes stronger. In this case, it is advantageous in reducing the size of the entire product. However, the fluctuation of coma aberration and distortion generated in the first lens group becomes large, and it becomes difficult to correct the aberration. Alternatively, when the value of the conditional expression (2) is less than the lower limit value, the refractive power of the second lens group becomes weak. That is, the second lens group, which is the focus group, becomes large. Therefore, the focus focusing speed becomes slow. Further, when the focus group becomes large, the drive mechanism for moving the focus group in the optical axis direction becomes large. Therefore, the size of the entire product is also increased. From these facts, it is not preferable that the value of the conditional expression (2) is less than the lower limit value.

In order to obtain these effects, the lower limit of the conditional expression (2) is more preferably 1.1, further preferably 1.2, and even more preferably 1.3. The upper limit of the conditional expression (2) is more preferably 3.9, further preferably 3.8, and even more preferably 3.7.

1-2-3. Conditional expression (3)
-11.0 ≤ f2a / f2b ≤ 5.0 ... (3)
However,
f2a: Focal length of the 2nd A subgroup f2b: Focal length of the 2B subgroup

In the conditional equation (3), in the optical system, the focal length of the second A subgroup arranged on the object side of the aperture and the focal length of the second B subgroup arranged on the image side of the aperture in the second lens group are set. The ratio is specified. By satisfying the conditional equation (3), the arrangement of the refractive power of the diaphragm with respect to the object side and the image side in the second lens group is optimized, aberration fluctuation during focusing is suppressed, and an optical system with high optical performance is suppressed. Can be obtained.

On the other hand, when the value of the conditional expression (3) exceeds the upper limit value, the second B portion arranged on the image side of the aperture with respect to the second A portion arranged on the object side of the aperture in the second lens group. The refractive power of the group becomes strong, and it becomes difficult to correct various aberrations, particularly spherical aberration, astigmatism, and distortion. On the other hand, when the value of the conditional expression (3) is less than the lower limit, the aberration of the second A subgroup arranged on the object side of the aperture with respect to the second B subgroup arranged on the image side of the aperture in the second lens group. The force becomes stronger, and it becomes difficult to correct various aberrations, particularly spherical aberration, coma, astigmatism, and distortion.

In order to obtain these effects, the lower limit of the conditional expression (3) is more preferably -10.95, further preferably -10.9, and even more preferably -10.85. .. The upper limit of the conditional expression (3) is more preferably 4.9, further preferably 4.8, and even more preferably 4.7.

1-2-4. Conditional expression (4)
-2.0 ≤ (R2a + R2b) / (R2a-R2b) ≤ 4.0 ... (4)
However,
R2a: Curvature radius of the lens surface on the most image side of the 2A subgroup R2b: Curvature radius of the lens surface on the most object side of the 2B subgroup The sign of the radius of curvature is the apex of the lens surface (lens surface and light). If the intersection with the axis) is located on the object side with respect to the center of the spherical surface of the lens surface, it is positive, and if it is located on the image side, it is negative.

Conditional expression (4) is an expression that defines the radius of curvature of the lens surface most arranged on the image side in the second A subgroup and the radius of curvature of the lens surface arranged most on the object side in the second B subgroup. be. That is, it is an equation relating to the shape factor (hereinafter, shape factor) of the air lens formed by the lens surfaces arranged on the object side and the image side of the air spacing in which the diaphragm is arranged. By satisfying the conditional equation (4), an air lens having similar radii of curvature on both sides is included in the second lens group, and the second lens group has a double Gauss type lens configuration. Therefore, it becomes easy to correct spherical aberration, coma aberration, and sagittal coma flare with a small number of lenses, and it becomes easy to obtain an optical system having better optical performance. Further, by adopting this configuration, the amount of aberration generated in the second lens group can be reduced, so that the aberration fluctuation due to the movement of the second lens group at the time of focusing can be reduced.

In order to obtain these effects, the lower limit of the conditional expression (4) is more preferably -1.95 and further preferably -1.90. The upper limit of the conditional expression (4) is more preferably 3.95, and even more preferably 3.90.

1-2-5. Conditional expression (5)
In the optical system, the first lens group preferably has at least one lens having a concave object side surface. At this time, the first lens group has at least one positive lens P1 satisfying the following conditional expression (5), and the positive lens P1 has a radius of curvature of the side surface of the object among the lenses having a concave side surface of the object. It is preferable that the lens is arranged on the image side rather than the lens having the smallest absolute value of.

ν1 ≤ 30 (5)
However,
ν1: Abbe number on the d line of the positive lens P1

The conditional expression (5) is an expression that defines the Abbe number with respect to the d-line of the positive lens P1. The positive lens P1 is preferably arranged on the image side of the lens having the side surface of the object having the smallest absolute value of the radius of curvature (larger curvature) in the first lens group. The smaller the F-number of the optical system, that is, the larger the aperture lens, the more likely the sagittal coma flare becomes a problem. Further, with a large-diameter lens, the problems of axial chromatic aberration and chromatic aberration of magnification tend to become prominent.

Therefore, by arranging the lens having a concave object side surface in the first lens group, it is possible to effectively correct the sagittal coma flare generated in the large-diameter lens. Further, at this time, a positive lens P1 having anomalous dispersibility satisfying the conditional equation (5) is arranged on the image side of the lens having the side surface of the object having the smallest absolute value of the radius of curvature (larger curvature) in the first lens group. This makes it possible to effectively correct the axial chromatic aberration and reduce the residual chromatic aberration. By satisfying the matter concerning the conditional expression (5) in this way, it is possible to more effectively suppress the occurrence of these aberrations, which tend to be a problem in a large-diameter lens, and obtain an optical system having higher optical performance.

In order to obtain these effects, the upper limit of the conditional expression (5) is more preferably 25, and even more preferably 21.

1-2-6. Conditional expression (6)
In the optical system, the second group lens group preferably has at least one positive lens P2 satisfying the following conditional expression (6).
ν2 ≧ 68 ・ ・ ・ ・ ・ (6)
However,
ν2: Abbe number on the d line of the positive lens P2

The conditional expression (6) is an expression that defines the Abbe number with respect to the d line of the positive lens P2. The smaller the F-number of the optical system, that is, the larger the aperture lens, the more prominent the problems of axial chromatic aberration and lateral chromatic aberration. By arranging the positive lens P2 having anomalous dispersibility satisfying the conditional equation (6) in the optical system in the second lens group, the occurrence of these aberrations, which tends to be a problem in a large-diameter lens, is suppressed and the optical performance is improved. A high optical system can be obtained.

1-2-7. Conditional expression (7)
0.60 ≤ f / f2 ≤ 0.85 (7)
However,
f: Focal length at infinity focusing of the optical system f2: Focal length of the second lens group

The conditional expression (7) is an expression that defines the ratio between the focal length of the optical system at in-focus and the focal length of the second lens group. By satisfying the conditional equation (7), the focal length of the second lens group with respect to the focal length of the optical system is optimized, and the miniaturization of the second lens group, which is the focus group, can be realized. At the same time, it is possible to suppress aberration fluctuations during focusing, and it is possible to obtain an optical system with high optical performance.

On the other hand, when the value of the conditional expression (7) is less than the lower limit value, the focal length of the second lens group becomes large. That is, since the refractive power of the second lens group, which is the focus group, is weakened, the amount of movement of the second lens group in the optical axis direction during focusing is increased, and therefore the optical system is large. Invite the change. On the other hand, when the value of the conditional expression (7) exceeds the upper limit value, the focal length of the second lens group becomes smaller. That is, since the refractive power of the second lens group, which is the focus group, becomes stronger, it is advantageous in reducing the size of the focus group. However, when the refractive power of the second lens group becomes stronger, the eccentric sensitivity of the second lens group becomes stronger due to a lens manufacturing error, and the image plane fluctuation becomes remarkable. Further, in this case, the aberration fluctuation becomes large at the time of focusing. Therefore, it becomes difficult to obtain an optical system having high optical performance.

In order to obtain these effects, the lower limit of the conditional expression (7) is more preferably 0.61 and even more preferably 0.62. The upper limit of the conditional expression (7) is more preferably 0.84 and even more preferably 0.83.

1-2-8. Conditional expression (8)
-45.0 ≤ G1Rr / f ≤ 7.0 ... (8)
However,
G1Rr: Radius of curvature of the lens surface on the most image side of the first lens group f: Focal length at infinity focusing of the optical system

The conditional equation (8) is an equation that defines the ratio between the radius of curvature of the lens surface on the image side of the first lens group and the focal length at infinity focusing of the optical system. By satisfying the conditional equation (8), the luminous flux diameter and the incident angle of the light beam incident on the second lens group can be controlled, and the aberration fluctuation at the time of focusing can be suppressed while reducing the size of the second lens group. It is possible to suppress and obtain an optical system with high optical performance.

On the other hand, when the value of the conditional expression (8) is less than the lower limit value, the lens surface on the most image side of the first lens group becomes a blunt convex shape toward the object side, and the angle of light incident on the second lens group becomes smaller. Therefore, the second lens group, which is the focus group, becomes large. Therefore, it is disadvantageous for miniaturizing the focus group. Further, when the value of the conditional expression (8) exceeds the upper limit value, the lens surface on the most image side of the first lens group becomes a blunt concave shape toward the object side, and the focus group can be miniaturized in the same manner as the lower limit value. Is at a disadvantage.

In order to obtain these effects, the lower limit of the conditional expression (8) is more preferably -44.5, further preferably −44.0, and even more preferably -43.5. .. The upper limit of the conditional expression (8) is more preferably 6.8, further preferably 6.5, and even more preferably 6.0.

1-2-9. Conditional expression (9)
-65.0 ≤ G1Fr / f ≤ 6.0 ... (9)
However,
G1Fr: Radius of curvature of the lens surface on the most object side of the first lens group

Conditional expression (9) is an expression that defines the ratio between the radius of curvature of the lens surface on the most object side of the first lens group and the focal length at infinity focusing of the optical system. By satisfying the conditional equation (9), the refractive power on the lens surface on the most object side of the first lens group is optimized. As a result, it becomes easy to correct the sagittal coma flare, which tends to be a problem with a large-diameter lens, and it becomes easier to obtain an optical system having high optical performance. At the same time, it is possible to suppress aberration fluctuations during focusing and to reduce the size of the entire product.

On the other hand, when the value of the conditional expression (9) is less than the lower limit value, the lens surface on the most object side of the first lens group becomes a blunt concave shape with a large radius of curvature, and the correction effect of sagittal flare becomes small. It ends up. In addition, the size of the first lens group is increased, which makes it difficult to reduce the size of the entire product. On the other hand, when the value of the conditional expression (9) exceeds the upper limit value, the lens surface on the most object side of the first lens group becomes a convex shape, and the refractive power of the lens surface becomes large. Therefore, it is advantageous in reducing the front lens diameter, but it is necessary to correct the aberration generated on the lens surface on the most object side of the first lens group in the second and subsequent lens groups, which is good for aberration correction. Becomes difficult to do. The incident angle of the light beam with respect to the second lens group becomes large, and the aberration fluctuation becomes large at the time of focusing.

In order to obtain these effects, the lower limit of the conditional expression (9) is more preferably -64.0 and even more preferably -63.0. The upper limit of the conditional expression (9) is more preferably 5.9 and even more preferably 5.8.

1-2-10. Conditional expression (10)
0.5 ≤ BF / Y ≤ 1.3 ... (10)
However,
BF: Distance on the optical axis from the lens plane on the image side of the third lens group to the image plane Y: Maximum image height of the image plane in the optical system

Conditional expression (10) defines the ratio of the distance on the optical axis from the lens plane on the image side of the third lens group to the image plane, that is, the so-called back focus, and the maximum image height of the image plane in the optical system. It is an expression. By satisfying the conditional expression (10), it is possible to suppress insufficient peripheral illumination and pixel shading due to eclipse occurring on the light receiving surface of the image sensor, and to obtain an optimum optical system for a mirrorless camera having a short back focus.

On the other hand, when the value of the conditional expression (10) is less than the lower limit value, the back focus is shortened, so that the total optical length of the optical system is shortened, which is advantageous in reducing the overall size. However, the incident angle of the main ray incident on the image plane from the lens surface on the most image side of the optical system becomes large, and the incident angle of the main ray allowed by the on-chip microlens provided for each pixel on the light receiving surface of the image sensor. The amount of ambient light is insufficient or shading occurs. On the other hand, when the value of the conditional expression (10) exceeds the upper limit value, the back focus becomes long, so that the total optical length of the optical system becomes long and it becomes difficult to reduce the overall size. Therefore, it is not preferable as an optical system of a small image pickup device that does not require a reflex mirror such as a mirrorless single-lens camera.

In order to obtain these effects, the lower limit of the conditional expression (10) is more preferably 0.55 and even more preferably 0.60. The upper limit of the conditional expression (10) is more preferably 1.25 and even more preferably 1.20.

1-2-11. Conditional expression (11)
−45 ≦ Exp <0 ・ ・ ・ ・ ・ (11)
However,
Exp: Exit pupil position of the optical system The exit pupil position represents the distance (mm) on the optical axis from the image plane to the exit pupil, and when the exit pupil is located on the object side of the image plane. The sign is negative.

The conditional expression (11) is an expression that defines the exit pupil position of the optical system. By satisfying the conditional expression (11), it becomes easier to obtain an optical system having a small size as a whole while reducing the diameter of the second lens group. Further, by satisfying the conditional expression (11), it becomes easy to correct the coma aberration generated in the first lens group, and it becomes easy to obtain an optical system having higher optical performance.

On the other hand, if the conditional equation (11) is not satisfied, it becomes difficult to reduce the diameter of the second lens group, and it becomes difficult to correct the coma aberration generated in the first lens group. It becomes difficult to obtain an optical system that is small and has high optical performance.

In order to obtain these effects, the lower limit of the conditional expression (11) is more preferably −45. The upper limit of the conditional expression (11) is more preferably −25 and even more preferably −26.

1-2-12. Conditional expression (12)
0.45 ≤ FD / f ≤ 1.14 (12)
However,
FD: Distance on the optical axis from the most object-side lens surface of the second lens group to the most image-side lens f: Focal length at infinity focusing of the optical system

Conditional expression (12) sets the ratio of the distance on the optical axis from the most object-side lens surface to the most image-side lens of the second lens group, which is the focus lens group, to the focal length of the optical system at infinity focusing. It is a formula to specify. By satisfying the conditional expression (12), it is possible to optimize the size and weight of the focus lens group while suppressing aberration fluctuations during focusing, and it is possible to realize faster autofocus. ..

In order to obtain these effects, the lower limit of the conditional expression (12) is more preferably 0.50, further preferably 0.55, and even more preferably 0.60. The upper limit of the conditional expression (12) is more preferably 1.10, further preferably 1.05, and even more preferably 1.00.
2. Imaging Device Next, the imaging device according to the present invention will be described. The image pickup apparatus according to the present invention is characterized by including the above-mentioned optical system according to the present invention and an image pickup element that converts an optical image formed by the optical system into an electrical signal. The image sensor is preferably provided on the image side of the optical system.

Here, the image sensor or the like is not particularly limited, and a solid-state image sensor such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can also be used. The image pickup device according to the present invention is suitable for an image pickup device using these solid-state image pickup elements such as a digital camera and a video camera. Further, the image pickup device can be applied to various image pickup devices such as a single-lens reflex camera, a mirrorless single-lens camera, a digital still camera, a surveillance camera, an in-vehicle camera, and a drone-mounted camera. Further, these image pickup devices may be interchangeable lens type image pickup devices, or may be lens-fixed image pickup devices in which the lenses are fixed to the housing.

Next, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the following examples.

(1) Optical Configuration FIG. 1 is a cross-sectional view of a lens showing a lens configuration of the optical system of the first embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 has a biconcave lens L1, a biconvex lens L2, a biconcave lens L3, a biconvex lens L4, a positive meniscus lens L5 with a convex surface facing the object side, and a convex surface toward the object side, in order from the object side. It is composed of a negative meniscus lens L6 that is directed.

The second lens group G2 includes a positive meniscus lens L7 having a convex surface facing the object side, a negative meniscus lens L8 having a convex surface facing the object side, an aperture diaphragm S, and a biconcave lens L9 in order from the object side. It is composed of a biconvex lens L10 and a biconcave lens L11.

The third lens group G3 is composed of a biconvex lens L12 and a biconcave lens L13.

In FIG. 1, “IP” is an image plane, and specifically, indicates an image pickup surface of a solid-state image sensor such as a CCD sensor or a CMOS sensor, a film surface of a silver salt film, or the like. Further, a cover glass CG or the like is provided on the object side of the IP. Since this point is the same in the cross-sectional views of each lens shown in other examples, the description thereof will be omitted below.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. First, Table 1 shows the surface data of the optical system. In Table 1, "plane number" is the order of the lens surfaces counted from the object side, "R" is the radius of curvature of the lens surface, "D" is the distance on the optical axis of the lens surface, and "Nd" is the d line (wavelength). The refractive index with respect to λ = 587.6 nm) and “νd” indicate the Abbe number with respect to the d line. Further, "ASPH" displayed in the column next to the surface number indicates that the lens surface is an aspherical surface, and "STOP" indicates an aperture diaphragm. The unit of length in Table 1 and each table shown below is "mm", and the unit of angle of view is "°". "INF" in each table represents infinity, and "0.0000" in the radius of curvature column represents a plane.

Next, Table 2 is a table of specifications of the optical system. “F” shown in Table 2 is the focal length of the entire optical system when the object is in focus at infinity, “Fno” is the F value, “ω” is the half angle of view, and “Y” is the image. It is high.

Table 3 shows the variable interval data of the optical system. Table 3 shows the distance between each lens surface at infinity focusing and closest focusing. Table 4 shows the focal lengths of each lens group.

Table 5 shows the aspherical data of the optical system. The aspherical data shown in Table 5 show the aspherical coefficient when the aspherical shape is defined by the following equation. However, in the table, "E-a" is an exponential notation and indicates ^{"× 10-a".} In the following equation, "x" is the amount of displacement from the reference plane in the optical axis direction, "r" is the radius of curvature of the near axis, "h" is the height from the optical axis in the direction perpendicular to the optical axis, and "k". Is the conical coefficient, and "An" is the nth-order aspherical coefficient.

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

Further, the numerical values of the conditional expressions (1) to (12) are shown in Table 51. Since the matters related to these tables are the same in each table shown in other examples, the description thereof will be omitted below.

2 and 3 show a longitudinal aberration diagram and a transverse aberration diagram when the optical system is in focus at infinity. Further, FIGS. 4 and 5 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system.
In each longitudinal aberration diagram, spherical aberration, astigmatism, and distortion are shown in order from the left when facing the drawing. In the diagram showing spherical aberration, the vertical axis is the ratio to the open F value, the horizontal axis is defocused, the solid line is the d line (wavelength λ = 587.56 nm), and the dotted line is the g line (wavelength λ = 435.84 nm). Shows the spherical aberration in. In the figure showing astigmatism, the vertical axis shows the angle of view and the horizontal axis shows the sagittal image plane (ds) with respect to the d line, and the dotted line shows the meridional image plane (dm) with respect to the d line. In the figure showing the distortion, the vertical axis represents the angle of view and the horizontal axis represents%, and the distortion is represented.

In each transverse aberration diagram, 100% image point (1.0 ω), 90% image point (0.9 ω), 70% image point (0.7 ω), and 50% image of the maximum image height are in order from the top. It shows the lateral aberration at the point (0.5ω) and the on-axis point (0.0ω). In each lateral aberration diagram, the horizontal axis represents the distance from the main ray on the pupil plane, the solid line indicates the coma aberration at the d line, and the dotted line indicates the coma aberration at the g line. Since the matters related to each of these figures are the same in the longitudinal aberration diagram and the transverse aberration diagram shown in other examples, the description thereof will be omitted below.

The back focus "BF" of the optical system at infinity is as follows. However, the following values include a cover glass (Nd = 1.5168) having a thickness of 2.5 mm, and the same applies to the back focus shown in other examples.
BF = 16.600mm

[Table 1]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 -94.6296 1.5000 1.51823 58.96
2 75.0375 15.8844
3 75.5480 14.0994 1.72916 54.67
4 -90.9397 0.2918
5 -88.5412 1.5000 1.75520 27.53
6 59.8596 0.9316
7 65.1851 10.8924 1.72916 54.67
8 -187.5360 0.1500
9 50.5953 8.8546 2.00272 19.32
10 410.2957 1.7890
11 298.0796 1.5000 1.80518 25.46
12 41.5484 D12
13 24.2786 10.9459 1.55032 75.50
14 14064.3710 0.1500
15ASPH 69.6775 1.5002 1.72825 28.32
16ASPH 24.0951 5.2800
17STOP 0.0000 1.0000
18 -129.4570 1.5005 1.51680 64.20
19 65.2073 4.7592
20 47.7786 6.8191 1.77250 49.62
21 -40.0944 0.1500
22ASPH -54.8492 2.3991 1.63980 34.57
23ASPH 836.9807 D23
24 129.8981 9.4607 1.81600 46.57
25 -65.1008 0.7774
26ASPH -44.7658 1.5000 1.63980 34.57
27ASPH 66.5000 2.2000
28 0.0000 10.9000
29 0.0000 2.5000 1.51680 64.20
30 0.0000 D30
31 0.0000 D31

[Table 2]
(Specifications)
f 50.4526 46.9268
Fno 1.2400 1.5079
ω 23.1157 20.3987
Y 21.633 21.633

[Table 3]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 295.7043
D12 11.3879 2.8928
D23 2.6002 11.0953
D30 1.0228 1.0724
D31 -0.0228 -0.0724

[Table 4]
(Focal length of each lens group)
Group surface number Focal length
G1 1-12 163.7300
G2 13-23 65.0079
G3 24-27 -230.3980

[Table 5]
(Aspherical data)
Surface number k A4 A6 A8 A10
15 0.00000E + 00 -1.13974E-05 -3.60566E-09 -7.33362E-12 1.61471E-14
16 0.00000E + 00 2.11674E-06 3.61159E-09 7.46297E-11 -3.27432E-13
22 0.00000E + 00 5.64344E-05 -2.56316E-07 6.93847E-10 -9.78946E-13
23 0.00000E + 00 6.37322E-05 -2.49423E-07 7.08430E-10 -1.03265E-12
26 0.00000E + 00 6.88348E-06 -4.33838E-08 2.33885E-10 -4.15610E-13
27 0.00000E + 00 4.59973E-06 -2.81731E-08 1.45117E-10 -2.18668E-13

(1) Optical Configuration FIG. 6 is a cross-sectional view of a lens showing a lens configuration of the optical system of the second embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 includes a biconcave lens L1, a biconvex lens L2, a biconcave lens L3, a biconvex lens L4, a positive meniscus lens L5 with a convex surface facing the object side, and a convex surface toward the object side, in order from the object side. It is composed of a negative meniscus lens L6 facing the lens.

The second lens group G2 has a positive meniscus lens L7 with a convex surface facing the object side, a negative meniscus lens L8 with a convex surface facing the object side, an aperture aperture S, and a concave surface on the object side in order from the object side. It is composed of a positive meniscus lens L9, a biconvex lens L10 with a convex surface facing the object side, and a biconcave lens L11.

The third lens group G3 is composed of a biconvex lens L12 and a biconcave lens L13.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 6 shows the surface data of the optical system. Table 7 is a specification table of the optical system. Table 8 shows the variable spacing data of the optical system, and Table 9 shows the focal length of each lens group. Table 10 shows aspherical data of the optical system. Further, FIGS. 7 and 8 show a longitudinal aberration diagram and a transverse aberration diagram at infinity focusing of the optical system. Further, FIGS. 9 and 10 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 16.600 mm.

[Table 6]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 -70.7889 1.5000 1.75129 28.66
2 81.7347 2.9442
3 106.3773 9.6413 2.01033 19.29
4 -147.1497 2.6361
5 -87.9583 1.5000 1.68006 31.56
6 94.6589 0.1500
7 93.2486 13.7064 1.75761 53.13
8-79.1271 0.1500
9 43.8102 9.8815 1.73310 55.71
10 335.2450 0.1500
11 249.3815 1.5000 1.70328 29.95
12 46.0948 D12
13ASPH 27.0426 8.2639 1.73224 55.75
14ASPH 128.2438 0.1500
15 89.9059 1.5000 1.68881 30.95
16 23.3460 6.7725
17STOP 0.0000 9.0000
18ASPH 1559.1081 2.2982 1.81921 46.73
19ASPH -148.2215 1.5796
20 54.6558 6.2834 1.54039 74.02
21 -34.5762 0.1500
22 -223.9459 1.5000 1.45913 70.94
23 27.3873 D23
24 96.3359 3.3086 2.00898 26.21
25 -140.2277 0.6324
26ASPH -133.6655 2.3500 1.75090 27.60
27ASPH 46.0526 2.2000
28 0.0000 10.9000
29 0.0000 2.5000 1.51680 64.20
30 0.0000 D30
31 0.0000 D31

[Table 7]
(Specifications)
f 51.0020 47.6028
Fno 1.2393 1.4918
ω 22.7937 20.2760
Y 21.633 21.633

[Table 8]
(Variable interval (when in focus))
Shooting distance INF closest
D0 INF 312.1355
D12 10.8299 2.0254
D23 2.8366 11.6411
D30 0.9972 1.0502
D31 0.0028 -0.0502

[Table 9]
(Focal length of each lens group)
Group surface number Focal length
G1 1-12 150.9220
G2 13-23 69.2971
G3 24-27 -286.3400

[Table 10]
(Aspherical data)
Surface number k A4 A6 A8 A10
13 0.00000E + 00 -8.44404E-07 6.21307E-10 -1.85575E-12 -2.28565E-15
14 0.00000E + 00 4.10691E-06 1.66494E-09 -1.17183E-11 1.68746E-14
18 0.00000E + 00 -1.45522E-05 -3.02460E-08 -1.92085E-10 5.97747E-13
19 0.00000E + 00 -6.84598E-06 -3.11453E-08 -9.62720E-11 4.20959E-13
26 0.00000E + 00 -2.35480E-05 1.27462E-07 -3.66326E-10 4.60566E-13
27 0.00000E + 00 -2.30470E-05 1.10331E-07 -2.99291E-10 3.40548E-13

(1) Optical Configuration FIG. 11 is a cross-sectional view of a lens showing a lens configuration of the optical system of the third embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 is composed of a negative meniscus lens L1 having a convex surface facing the object side, a biconcave lens L2, a biconvex lens L3, a biconcave lens L4, a biconvex lens L5, and a biconvex lens L6 in order from the object side. It is composed.

The second lens group G2 is composed of a positive meniscus lens L7 having a convex surface facing the object side, an open diaphragm S, a biconcave lens L8, a biconvex lens L9, a biconvex lens L10, and a biconcave lens L11 in order from the object side. It is composed.

The third lens group G3 is composed of a biconvex lens L12 and a biconcave lens L13 in order from the object side.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 11 shows the surface data of the optical system. Table 12 is a specification table of the optical system. Table 13 shows the variable interval data of the optical system, and Table 14 shows the focal length of each lens group. Table 15 shows aspherical data of the optical system. 12 and 13 show a longitudinal aberration diagram and a transverse aberration diagram when the optical system is in focus at infinity. Further, FIGS. 14 and 15 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 16.600 mm.

[Table 11]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1ASPH 276.1145 3.4044 1.61143 37.00
2ASPH 140.3388 9.1070
3 -63.4578 3.1734 1.70479 29.84
4 176.3144 0.1500
5 80.3325 7.8667 2.01226 19.09
6 -338.6297 3.9009
7 -88.6347 1.5000 1.76620 26.86
8 63.6475 0.2935
9 65.3064 12.7358 1.70758 57.03
10 -89.1107 0.1500
11 79.8415 7.0213 1.69347 57.76
12 -625.5055 D12
13ASPH 26.3584 7.2549 1.45887 86.57
14ASPH 44.6041 5.0365
15STOP 0.0000 6.5000
16 -39.6107 1.5001 1.70131 30.08
17 445.5192 3.1928
18 42.3566 6.3732 1.71425 56.69
19 -85.1550 3.3297
20ASPH 153.0506 4.8349 1.80322 48.38
21ASPH -58.1518 0.1500
22 -92.0043 1.5000 1.54775 54.86
23 36.6332 D23
24 109.5591 4.1360 1.91959 36.57
25 -234.8559 1.3203
26 -61.1780 1.5002 1.56545 43.11
27 53.6860 2.2000
28 0.0000 10.9000
29 0.0000 2.5000 1.51680 64.20
30 0.0000 D30
31 0.0000 D31
[Table 12]
(Specifications)
f 51.0023 46.4435
Fno 1.2393 1.4829
ω 22.8505 20.9852
Y 21.633 21.633

[Table 13]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 305.1329
D12 10.3588 2.0283
D23 1.9486 10.2791
D30 1.0106 1.0281
D31 -0.0106 -0.0281

[Table 14]
(Focal length of each lens group)
Group surface number Focal length
G1 1-12 111.1040
G2 13-23 78.1628
G3 24-27 -146.4880
[Table 15]
(Aspherical data)
Surface number k A4 A6 A8 A10
1 0.00000E + 00 -4.01266E-06 4.61190E-09 -1.80836E-12 2.56740E-16
2 0.00000E + 00 -4.12430E-06 5.12268E-09 -1.86169E-12 4.36123E-16
13 0.00000E + 00 -5.77722E-07 1.30985E-09 -3.72057E-12 4.33285E-15
14 0.00000E + 00 -7.50856E-07 -3.94444E-09 -5.88653E-12 -2.21504E-14
20 0.00000E + 00 -1.61065E-05 -3.00861E-08 -7.05732E-11 3.91550E-14
21 0.00000E + 00 -2.90405E-06 -2.51867E-08 -4.01889E-11 3.22922E-14

(1) Optical Configuration FIG. 16 is a cross-sectional view of a lens showing a lens configuration of the optical system of the fourth embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 includes a biconcave lens L1, a negative meniscus lens L2 with a concave surface facing the object side, a positive meniscus lens L3 with a convex surface facing the object side, and a biconvex lens L4 in order from the object side. It is composed of a biconcave lens L5 and a biconvex lens L6.

The second lens group G2 includes a positive meniscus lens L7 having a convex surface facing the object side, an open diaphragm S, a biconcave lens L8, and a positive meniscus lens L9 having a convex surface facing the object side in order from the object side. It is composed of a convex lens L10 and a negative meniscus lens L11 with a convex surface facing the object side.

The third lens group G3 is composed of a positive meniscus lens L12 having a convex surface facing the object side and a negative meniscus lens L13 having a convex surface facing the object side in order from the object side.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 16 shows the surface data of the optical system. Table 17 is a specification table of the optical system. Table 18 shows the variable spacing data of the optical system, and Table 19 shows the focal length of each lens group. Table 20 shows aspherical data of the optical system. Further, FIGS. 17 and 18 show a longitudinal aberration diagram and a transverse aberration diagram at infinity focusing of the optical system. Further, FIGS. 19 and 20 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 16.600 mm.

[Table 16]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 -3022.7899 1.5000 1.48749 70.44
2 62.3354 16.6958
3-45.2053 9.6057 2.00069 25.46
4 -62.9415 0.1500
5 80.7639 7.6486 2.00272 19.32
6 823.2191 4.6182
7 68.3484 12.0625 1.49700 81.61
8 -124.7590 0.1930
9 -122.3261 1.5000 1.80518 25.46
10 46.9221 0.1502
11 47.0324 10.7775 1.72916 54.67
12 -637.1725 D12
13ASPH 28.8390 10.4189 1.49700 81.61
14ASPH 248.4090 2.0000
15STOP 0.0000 1.8972
16 -204.6469 1.5000 1.74077 27.76
17 34.6219 1.5287
18ASPH 62.8301 2.4211 1.95375 32.32
19ASPH 252.9157 11.1353
20 88.1659 4.4525 2.00100 29.13
21 -63.1234 0.1500
22 84.7637 1.5965 1.67270 32.17
23 27.2361 D23
24 49.2661 3.3399 2.00069 25.46
25 57.1297 1.9911
26ASPH 72.7711 1.5961 1.60342 38.01
27ASPH 32.4410 2.2000
28 0.0000 10.9000
29 0.0000 2.5000 1.51680 64.20
30 0.0000 D30
31 0.0000 D31

[Table 17]
(Specifications)
f 51.0294 46.6867
Fno 1.2372 1.4922
ω 22.8292 20.7799
Y 21.633 21.633
[Table 18]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 290.0637
D12 10.5682 1.9955
D23 3.7533 12.3260
D30 1.0048 1.0862
D31 -0.0048 -0.0862

[Table 19]
(Focal length of each lens group)
Group surface number Focal length
G1 1-12 132.2650
G2 13-23 75.4551
G3 24-27 -158.9940

[Table 20]
(Aspherical data)
Surface number k A4 A6 A8 A10
13 0.00000E + 00 1.19676E-06 2.11383E-09 -1.65197E-12 9.18533E-15
14 0.00000E + 00 3.47698E-06 -1.60755E-08 2.04458E-11 -8.72692E-15
18 0.00000E + 00 9.58359E-06 -1.24802E-08 1.73214E-11 1.75711E-14
19 0.00000E + 00 1.79339E-05 1.04831E-09 3.83777E-11 -2.53070E-14
26 0.00000E + 00 -5.28725E-05 1.69551E-07 -4.23502E-10 4.77132E-13
27 0.00000E + 00 -5.37800E-05 1.62979E-07 -4.13248E-10 4.28538E-13

(1) Optical Configuration FIG. 21 is a cross-sectional view of a lens showing a lens configuration of the optical system of the fifth embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 is composed of a biconcave lens L1, a biconcave lens L2, a biconvex lens L3, and a positive meniscus lens L4 having a convex surface facing the object side in order from the object side.

The second lens group G2 has a positive meniscus lens L5 with a convex surface facing the object side, an aperture diaphragm S, a positive meniscus lens L6 with a convex surface facing the object side, and a convex surface toward the object side in order from the object side. It is composed of a negative meniscus lens L7, a biconcave lens L8, and a biconvex lens L9.

The third lens group G3 is composed of a biconvex lens L10, a biconcave lens L11, a positive meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a convex surface facing the object side.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 21 shows the surface data of the optical system. Table 22 is a specification table of the optical system. Table 23 shows the variable interval data of the optical system, and Table 24 shows the focal length of each lens group. Table 25 shows aspherical data of the optical system. 22 and 23 show a longitudinal aberration diagram and a transverse aberration diagram when the optical system is in focus at infinity. Further, FIGS. 24 and 25 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 16.600 mm.

[Table 21]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 -324.8462 1.5000 1.80518 25.46
2 156.8866 9.5037
3-59.8776 4.9243 1.78472 25.72
4 119.9576 0.2387
5 123.4101 13.1339 1.77250 49.62
6 -69.1275 0.1500
7 72.0534 7.9806 2.00272 19.32
8 282.9942 D 8
9 31.3056 4.8922 1.55032 75.50
10 40.4454 13.4882
11STOP 0.0000 0.5000
12 23.3677 6.8027 1.49700 81.61
13 60.3173 1.2291
14ASPH 54.4013 1.5000 1.68893 31.16
15ASPH 23.4901 7.8371
16ASPH -39.9043 1.5000 1.74077 27.76
17ASPH 202.4775 0.1500
18 81.5493 6.5397 1.77250 49.62
19 -31.6986 D19
20 164.5486 3.9804 1.80420 46.50
21 -60.8106 0.1641
22 -60.2905 1.5000 1.69895 30.05
23 56.5518 0.4645
24 66.7930 10.8743 2.00272 19.32
25 135.4604 0.6160
26ASPH 61.0634 1.5000 1.74950 35.28
27ASPH 35.6374 2.2000
28 0.0000 10.9000
29 0.0000 2.5000 1.51680 64.20
30 0.0000 D30
31 0.0000 D31

[Table 22]
(Specifications)
f 50.3910 46.5148
Fno 1.2451 1.4823
ω 23.0490 21.2640
Y 21.633 21.633

[Table 23]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 296.0564
D 8 16.1104 7.4913
D19 0.2049 8.8240
D30 1.0007 1.0587
D31 -0.0014 -0.0594

[Table 24]
(Focal length of each lens group)
Group surface number Focal length
G1 1-8 159.0630
G2 9-19 72.6673
G3 20-27 -177.1130

[Table 25]
(Aspherical data)
Surface number k A4 A6 A8 A10
14 0.00000E + 00 -1.69248E-05 8.73623E-08 -2.66697E-10 3.54765E-13
15 0.00000E + 00 -1.00438E-05 9.21377E-08 -1.83133E-10 1.19267E-13
16 0.00000E + 00 -3.01212E-05 1.28165E-07 -4.83380E-10 6.61264E-13
17 0.00000E + 00 -1.90905E-05 1.31069E-07 -4.34227E-10 6.66782E-13
26 0.00000E + 00 -5.47402E-05 1.64663E-07 -2.57442E-10 2.14302E-13
27 0.00000E + 00 -5.62708E-05 1.75051E-07 -3.06962E-10 2.94860E-13

(1) Optical Configuration FIG. 26 is a cross-sectional view of a lens showing a lens configuration of the optical system of the sixth embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 is composed of a biconcave lens L1, a biconcave lens L2, a biconvex lens L3, and a positive meniscus lens L4 having a convex surface facing the object side in order from the object side.

The second lens group G2 includes a positive meniscus lens L5 having a convex surface facing the object side, a positive meniscus lens L6 having a convex surface facing the object side, and a negative meniscus lens L6 having a convex surface facing the object side in order from the object side. It is composed of a lens L7, an aperture stop S, a biconcave lens L8, and a biconvex lens L9.

The third lens group G3 is composed of a biconvex lens L10, a biconcave lens L11, a positive meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a convex surface facing the object side.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 26 shows the surface data of the optical system. Table 27 is a specification table of the optical system. Table 28 shows the variable spacing data of the optical system, and Table 29 shows the focal length of each lens group. Table 30 shows aspherical data of the optical system. Further, FIGS. 27 and 28 show a longitudinal aberration diagram and a transverse aberration diagram when the optical system is in focus at infinity. Further, FIGS. 29 and 30 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 16.600 mm.

[Table 26]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 -178.3173 1.5000 1.80518 25.46
2 297.7825 10.1391
3 -55.1243 2.8640 1.72825 28.32
4 110.2646 0.2550
5 113.3491 14.5690 1.72916 54.67
6 -64.9892 0.1500
7 65.8878 10.1933 2.00272 19.32
8 169.8172 D 8
9 26.8947 6.0882 1.55032 75.50
10 37.3803 7.0078
11 25.1682 7.0014 1.55032 75.50
12 91.9564 0.1500
13ASPH 32.7090 1.5000 1.71736 29.50
14ASPH 17.6805 5.5000
15STOP 0.0000 2.0360
16ASPH -58.8732 1.5000 1.68893 31.16
17ASPH 54.1809 0.3098
18 90.9818 5.3139 1.77250 49.62
19 -34.5064 D19
20 167.3931 3.4606 1.80420 46.50
21 -60.9348 0.3717
22 -52.9967 1.5000 1.78472 25.72
23 50.1093 0.1500
24ASPH 41.5863 10.1711 2.00272 19.32
25ASPH 112.6103 0.4865
26 108.2792 1.5000 1.80518 25.46
27 54.9212 2.2000
28 0.0000 10.9000
29 0.0000 2.5000 1.51680 64.20
30 0.0000 D30
31 0.0000 D31

[Table 27]
(Specifications)
f 48.9700 46.2286
Fno 1.2455 1.5354
ω 23.7855 20.3760
Y 21.633 21.633

[Table 28]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 297.8854
D 8 21.6293 12.6021
D19 0.1500 9.1772
D30 0.9991 1.0178
D31 0.0009 -0.0178

[Table 29]
(Focal length of each lens group)
Group surface number Focal length
G1 1-8 180.9180
G2 9-19 75.9397
G3 20-27 -320.4910

[Table 30]
(Aspherical data)
Surface number k A4 A6 A8 A10
13 0.00000E + 00 -5.58681E-05 2.38386E-07 -6.45231E-10 6.04630E-13
14 0.00000E + 00 -5.08917E-05 2.47644E-07 -5.00160E-10 1.05206E-12
16 0.00000E + 00 -3.41953E-05 1.66087E-07 -3.28343E-10 1.20368E-13
17 0.00000E + 00 -3.38050E-05 1.61050E-07 -4.37966E-10 -2.18919E-14
24 0.00000E + 00 3.89704E-06 -6.01815E-09 8.09353E-11 -1.34313E-13
25 0.00000E + 00 6.40951E-06 -1.10954E-08 1.26766E-10 -1.27861E-13

(1) Optical Configuration FIG. 31 is a cross-sectional view of a lens showing a lens configuration of the optical system of the seventh embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 includes a biconcave lens L1, a biconvex lens L2, a biconcave lens L3, a biconvex lens L4, a positive meniscus lens L5 with a convex surface facing the object side, and a convex surface toward the object side, in order from the object side. Consists of a negative meniscus lens pointing towards.

The second lens group G2 includes a biconvex lens L7, a negative meniscus lens L8 with a convex surface facing the object side, a negative meniscus lens L9 with a convex surface facing the object side, an aperture stop S, and the like. It is composed of a biconvex lens L10 and a negative meniscus lens L11 with a convex surface facing the object side.

The third lens group G3 is composed of a biconvex lens L12 and a biconcave lens L13.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 31 shows the surface data of the optical system. Table 32 is a specification table of the optical system. Table 33 shows the variable spacing data of the optical system, and Table 34 shows the focal length of each lens group. Table 35 shows aspherical data of the optical system. Further, FIGS. 32 and 33 show a longitudinal aberration diagram and a transverse aberration diagram when the optical system is in focus at infinity. Further, FIGS. 34 and 35 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 16.600 mm.

[Table 31]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 -101.2648 1.5000 1.57046 42.84
2 65.0669 14.7068
3 123.4438 14.4997 1.73234 54.67
4 -61.7589 0.3661
5 -60.0954 1.5003 1.70444 30.05
6 92.9922 0.1500
7 62.1580 13.1923 1.73234 54.67
8 -143.4959 0.1500
9ASPH 49.0064 9.1087 2.01488 19.32
10ASPH 576.8137 0.6070
11 1366.9073 1.5000 1.79190 25.72
12 37.2552 D12
13 27.0890 10.1056 1.59488 68.62
14 -1651.9849 0.1500
15 335.4923 1.5000 1.60718 38.01
16 34.5526 3.4610
17ASPH 44.6905 2.2437 1.70444 30.05
18ASPH 22.8361 4.5000
19STOP 0.0000 6.2140
20 75.9197 7.0724 1.59561 67.00
21 -31.6714 0.1500
22 48.9794 2.3621 1.85504 23.78
23 37.8546 D23
24 125.5804 6.8250 1.90615 37.37
25 -59.6965 0.9761
26ASPH -36.1554 1.5000 1.72310 29.50
27ASPH 83.0663 2.2000
28 0.0000 10.9000
29 0.0000 2.5000 1.51872 64.20
30 0.0000 D30
31 0.0000 D31

[Table 32]
(Specifications)
f 48.9497 45.3402
Fno 1.2436 1.4704
ω 24.0284 21.5843
Y 21.633 21.633

[Table 33]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 295.1484
D12 9.7298 2.0013
D23 4.0973 11.8258
D30 1.0051 1.0835
D31 -0.0051 -0.0835

[Table 34]
(Focal length of each lens group)
Group surface number Focal length
G1 1-12 144.2830
G2 13-23 63.4543
G3 24-27 -187.9130

[Table 35]
(Aspherical data)
Surface number k A4 A6 A8 A10
9 0.00000E + 00 -2.12112E-07 1.40871E-10 -6.97635E-13 4.98826E-16
10 0.00000E + 00 -2.55181E-08 7.80142E-11 7.27063E-14 1.93331E-16
17 0.00000E + 00 -5.86060E-05 1.31448E-07 -2.46214E-10 1.77027E-13
18 0.00000E + 00 -5.07056E-05 1.59596E-07 -2.90185E-10 4.06226E-14
26 0.00000E + 00 1.83043E-05 -7.14342E-08 2.49409E-10 -3.57175E-13
27 0.00000E + 00 1.42376E-05 -6.39961E-08 2.23133E-10 -2.90825E-13

(1) Optical Configuration FIG. 36 is a cross-sectional view of a lens showing a lens configuration of the optical system of the eighth embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 has a positive refractive power in which both concave lenses L1 are joined in order from the object side, a positive meniscus lens L2 having a concave surface facing the object side, and a negative meniscus lens L3 having a concave surface facing the object side. It is composed of a junction lens, a biconvex lens L4, a positive meniscus lens L5 having a convex surface facing the object side, and a negative meniscus lens L6 having a convex surface facing the object side.

The second lens group G2 includes a biconvex lens L7, a biconcave lens L8, a negative meniscus lens L9 with a convex surface facing the object side, an aperture diaphragm S, a biconvex lens L10, and a convex surface toward the object side, in order from the object side. It is composed of a negative meniscus lens L11 facing the lens.

The third lens group G3 is composed of a biconvex lens L12 and a biconcave lens L13.
(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 36 shows the surface data of the optical system. Table 37 is a specification table of the optical system. Table 38 shows the variable spacing data of the optical system, and Table 39 shows the focal length of each lens group. Table 40 shows aspherical data of the optical system. Further, FIGS. 37 and 38 show a longitudinal aberration diagram and a transverse aberration diagram when the optical system is in focus at infinity. Further, FIGS. 39 and 40 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 19.202 mm.

[Table 36]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 0.0000 0.0000
2 -85.1131 1.8500 1.57046 42.84
3 76.0378 8.3913
4 -247.5665 11.6814 1.88814 40.80
5 -43.7541 0.0100 1.57046 42.84
6 -43.7541 1.5000 1.70984 29.87
7 -796.9730 7.2416
8 56.1319 12.8555 1.73234 54.67
9 -267.9060 0.1500
10ASPH 44.0344 8.6425 1.93322 20.88
11ASPH 197.4935 1.3379
12 495.8974 1.6500 1.80919 25.21
13 30.6186 D13
14 28.8951 9.2451 1.49845 81.61
15 -233.3336 1.5435
16 -505.7356 1.0000 1.60718 38.01
17 67.9556 1.7080
18ASPH 47.0367 2.7134 1.70444 30.05
19ASPH 22.1673 4.3532
20STOP 0.0000 7.7931
21 102.7552 7.9585 1.59561 67.00
22 -31.5171 0.1500
23 42.8009 2.3500 1.85504 23.78
24 38.3287 D24
25 60.6708 7.1611 1.90615 37.37
26 -153.0798 0.9761
27ASPH -121.2359 1.6500 1.72310 29.50
28ASPH 37.3475 4.8046
29 0.0000 10.9000
30 0.0000 2.5000 1.51872 64.20
31 0.0000 D31
32 0.0000 D32

[Table 37]
(Specifications)
f 48.4992 45.9535
Fno 1.2436 1.4791
ω 23.7734 21.3247
Y 21.633 21.633

[Table 38]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 290.3102
D13 12.5519 3.9878
D24 4.0443 12.6084
D31 0.9892 1.0575
D32 0.0108 -0.0575

[Table 39]
(Focal length of each lens group)
Group surface number Focal length
G1 1-13 211.9710
G2 14-24 59.1769
G3 25-28 -385.1600

[Table 40]
(Aspherical data)
Surface number k A4 A6 A8 A10
10 0.00000E + 00 -2.05496E-07 -1.63707E-10 -5.61330E-14 -2.38879E-16
11 0.00000E + 00 3.79999E-08 7.80142E-11 7.27063E-14 1.93331E-16
18 0.00000E + 00 -5.34497E-05 1.06784E-07 -1.90035E-10 1.27185E-13
19 0.00000E + 00 -5.18096E-05 1.26054E-07 -2.56412E-10 9.63138E-14
27 0.00000E + 00 1.29516E-06 8.14584E-09 -3.67532E-11 3.19064E-14
28 0.00000E + 00 4.00667E-06 7.19297E-09 1.13233E-11 -8.54751E-14

(1) Optical Configuration FIG. 41 is a cross-sectional view of a lens showing a lens configuration of the optical system of the ninth embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

The first lens group G1 has a positive refractive power in which both concave lenses L1 are joined in order from the object side, a positive meniscus lens L2 having a concave surface facing the object side, and a negative meniscus lens L3 having a concave surface facing the object side. It is composed of a junction lens, a biconvex lens L4, a positive meniscus lens L5 having a convex surface facing the object side, and a negative meniscus lens L6 having a convex surface facing the object side.

The second lens group G2 includes a biconvex lens L7, a negative meniscus lens L8 with a convex surface facing the object side, a negative meniscus lens L9 with a convex surface facing the object side, an aperture stop S, and the like. It is composed of a biconvex lens L10 and a negative meniscus lens L11 with a convex surface facing the object side.

The third lens group G3 is composed of a biconvex lens L12 and a biconcave lens L13.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 41 shows the surface data of the optical system. Table 42 is a specification table of the optical system. Table 43 shows the variable spacing data of the optical system, and Table 44 shows the focal length of each lens group. Table 45 shows aspherical data of the optical system. Further, FIGS. 42 and 43 show a longitudinal aberration diagram and a transverse aberration diagram at infinity focusing of the optical system. Further, FIGS. 44 and 45 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 18.867 mm.

[Table 41]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 0.0000 0.0000
2 -99.1726 1.8500 1.57046 42.84
3 57.5115 17.9343
4 -100.8669 12.0913 1.96073 32.32
5 -37.0139 0.0100 1.57046 42.84
6 -37.0139 1.5000 1.89575 24.70
7 -115.2453 0.2000
8 61.6442 13.5619 1.73234 54.67
9 -184.3133 0.1500
10ASPH 50.2660 8.0000 1.95824 17.98
11ASPH 313.0101 1.0675
12 935.9352 1.6500 1.81642 22.76
13 34.6237 D13
14 26.9700 9.6239 1.49845 81.61
15 -328.9105 0.6773
16 379.5778 1.7780 1.60718 38.01
17 43.0865 2.7918
18ASPH 48.8004 2.3688 1.70444 30.05
19ASPH 23.7062 5.0547
20STOP 0.0000 6.6103
21 109.4851 7.8738 1.59561 67.00
22 -29.5295 0.1500
23 41.6178 2.3500 1.85504 23.78
24 35.1886 D24
25 57.3129 8.0000 1.90615 37.37
26 -75.8988 0.5665
27ASPH -57.7160 1.6500 1.72310 29.50
28ASPH 39.8380 4.4707
29 0.0000 10.9000
30 0.0000 2.5000 1.51872 64.20
31 0.0000 D31
32 0.0000 D32

[Table 42]
(Specifications)
f 41.1995 39.9483
Fno 1.2436 1.4791
ω 28.1765 25.8344
Y 21.633 21.633

[Table 43]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 287.1416
D13 12.4021 5.6962
D24 4.0923 10.7982
D31 0.9834 1.0671
D32 0.0166 -0.0671

[Table 44]
(Focal length of each lens group)
Group surface number Focal length
G1 1-13 192.3420
G2 14-24 60.8848
G3 25-28 -1053.160

[Table 45]
(Aspherical data)
Surface number k A4 A6 A8 A10
10 0.00000E + 00 -9.41745E-08 -4.10448E-11 1.07603E-13 -3.47328E-16
11 0.00000E + 00 1.82922E-07 7.80142E-11 7.27063E-14 1.93331E-16
18 0.00000E + 00 -5.27715E-05 9.36304E-08 -1.62924E-10 7.73275E-14
19 0.00000E + 00 -4.47998E-05 1.18675E-07 -2.03020E-10 1.60676E-14
27 0.00000E + 00 3.51404E-06 4.96526E-09 -3.33435E-11 4.74925E-14
28 0.00000E + 00 4.70965E-06 3.95442E-09 1.97139E-11 -9.00491E-14
Surface number A12 A14 A16 A18 A20
10 4.82387E-19 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
11 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
18 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
19 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
27 -2.05077E-17 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
28 1.38604E-16 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00

(1) Optical Configuration FIG. 46 is a cross-sectional view of a lens showing a lens configuration of the optical system of the tenth embodiment according to the present invention at infinity in focus. The optical system is composed of 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 negative refractive power in order from the object side. Has been done. When focusing from an infinity object to a short-distance object, the second lens group G2 moves toward the object along the optical axis while the first lens group G1 and the third lens group G3 are fixed in the optical axis direction. Moving. The aperture diaphragm S is arranged in the second lens group G2. The second lens group G2 is composed of a second A subgroup G2A arranged on the object side with the aperture diaphragm S interposed therebetween and a second B subgroup G2B arranged on the image side. Hereinafter, the configuration of each lens group will be described.

In the first lens group G1, in order from the object side, a biconcave lens L1, a negative meniscus lens L2 with a concave surface facing the object side, a biconvex lens L3, a biconvex lens L4, a biconcave lens L5, and a biconvex lens L6 are joined. It is composed of a junction lens with positive refractive power.

The second lens group G2 includes a positive meniscus lens L7 with a convex surface facing the object side, an aperture diaphragm S, a biconcave lens L8, a biconcave lens L9, a biconvex lens L10, and a biconcave lens L11 in order from the object side. Consists of.

The third lens group G3 is composed of a biconvex lens L12 and a biconcave lens L13.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 46 shows the surface data of the optical system. Table 47 is a specification table of the optical system. Table 48 shows the variable spacing data of the optical system, and Table 49 shows the focal length of each lens group. Table 50 shows aspherical data of the optical system. Further, FIGS. 47 and 48 show a longitudinal aberration diagram and a transverse aberration diagram when the optical system is in focus at infinity. Further, FIGS. 49 and 50 show a longitudinal aberration diagram and a transverse aberration diagram at the time of the closest focusing of the optical system. The back focus "BF" of the optical system at infinity is as follows.
BF = 16.800mm

[Table 46]
(Surface data)
Surface number RD Nd νd
0 INF D 0
1 0.0000 0.0000
2 -125.8995 1.8000 1.48749 70.44
3 200.3442 10.1255
4 -61.6769 8.0000 2.00069 25.46
5 -81.2673 0.1500
6 104.2689 8.0000 1.94595 17.98
7 -10966.7140 4.8481
8 69.9146 10.6791 1.49700 81.61
9 -231.1553 0.0100 1.56732 42.84
10 -231.1553 1.5500 1.80518 25.46
11 44.9748 0.0100 1.56732 42.84
12 44.9748 12.6445 1.72916 54.67
13 -2595.3425 D13
14ASPH 29.4794 11.1479 1.49710 81.56
15ASPH 212.8332 6.3691
16STOP 0.0000 1.5061
17 -300.2268 1.5000 1.74077 27.76
18 47.6535 3.2500
19ASPH -8171.0229 3.6085 1.95375 32.32
20ASPH -1539.1683 5.4153
21 69.6562 6.5636 1.94443 33.17
22 -51.9668 0.1500
23 -304.5811 1.0000 1.61197 37.36
24 38.8618 D24
25 650.3867 3.5228 2.00069 25.46
26 -82.2573 1.5131
27ASPH -55.0840 1.0000 1.60342 38.01
28ASPH 60.0826 2.4051
29 0.0000 10.9000
30 0.0000 2.5000 1.51680 64.20
31 0.0000 D31
32 0.0000 D32

[Table 47]
(Specifications)
f 63.0073 55.1069
Fno 1.2396 1.6087
ω 18.6086 15.9908
Y 21.633 21.633

[Table 48]
(Variable interval (when in focus))
Shooting distance INF closest
D 0 INF 289.3587
D13 14.5882 2.0051
D24 4.9020 17.4851
D31 1.0019 1.0269
D32 -0.0019 -0.0269

[Table 49]
(Focal length of each lens group)
Group surface number Focal length
G1 1-13 152.6240
G2 14-24 81.9798
G3 25-28 -146.6960

[Table 50]
(Aspherical data)
Surface number k A4 A6 A8 A10
14 0.00000E + 00 6.58789E-07 2.19108E-09 -2.30307E-12 7.43074E-15
15 0.00000E + 00 3.66576E-06 -2.78989E-09 -1.72504E-12 1.96928E-15
19 0.00000E + 00 1.27830E-06 -8.39889E-09 -1.18007E-11 8.38800E-14
20 0.00000E + 00 9.95723E-06 1.45683E-09 1.91237E-12 7.61116E-14
27 0.00000E + 00 -2.15049E-05 1.87631E-07 -9.80666E-10 2.73235E-12
28 0.00000E + 00 -1.92323E-05 1.53480E-07 -7.40403E-10 1.89117E-12
Surface number A12 A14 A16 A18 A20
14 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
15 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
19 -3.89534E-18 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
20 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
27 -3.10642E-15 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
28 -1.96659E-15 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00

[Table 51]
Example 1 Example 2 Example 3 Example 4
Conditional expression (1) G2Fr / f 0.53 0.52 0.48 0.57
Conditional expression (2) f1 / f2 2.18 1.42 2.52 1.75
Conditional expression (3) f2a / f2b 3.44 0.83 1.79 1.94E-3
Conditional expression (4) (R2a + R2b) / (R2a-R2b) -1.03 0.06 -0.69 0.09
Conditional expression (5) ν1 19.32 19.32 19.09 19.32
Conditional expression (6) ν2 75.50 74.02 86.57 81.61
Conditional expression (7) f / f2 0.74 0.65 0.78 0.68
Conditional expression (8) G1Rr / f 0.90 -12.26 0.82 -12.49
Conditional expression (9) G1Fr / f -1.39 5.41 -1.88 -59.24
Conditional expression (10) BF / Y 0.77 0.77 0.77 0.77
Conditional expression (11) Exp -35.45 -38.54 -35.22 -39.45
Conditional expression (12) FD / f 0.68 0.74 0.78 0.73

Example 5 Example 6 Example 7 Example 8
Conditional expression (1) G2Fr / f 0.62 0.55 0.55 0.60
Conditional expression (2) f1 / f2 2.19 2.38 2.27 3.58
Conditional expression (3) f2a / f2b 0.91 0.90 -10.65 -9.80
Conditional expression (4) (R2a + R2b) / (R2a-R2b) 3.74 -0.54 -1.86 -1.55
Conditional expression (5) ν1 19.32 19.32 19.32 20.88
Conditional expression (6) ν2 75.50 75.50 68.62 81.61
Conditional expression (7) f / f2 0.69 0.64 0.77 0.82
Conditional expression (8) G1Rr / f 5.62 3.47 0.76 0.63
Conditional expression (9) G1Fr / f -6.45 -3.64 -2.07 -1.75
Conditional expression (10) BF / Y 0.77 0.77 0.77 0.89
Conditional expression (11) Exp -43.70 -29.89 -34.67 -39.86
Conditional expression (12) FD / f 0.88 0.74 0.77 0.80

Example 9 Example 10
Conditional expression (1) G2Fr / f 0.65 0.47
Conditional expression (2) f1 / f2 3.16 1.86
Conditional expression (3) f2a / f2b -9.80 -0.04
Conditional expression (4) (R2a + R2b) / (R2a-R2b) -1.55 -0.17
Conditional expression (5) ν1 17.98 17.98
Conditional expression (6) ν2 81.61 81.56
Conditional expression (7) f / f2 0.68 0.77
Conditional expression (8) G1Rr / f 0.84 -41.19
Conditional expression (9) G1Fr / f -2.41 -2.00
Conditional expression (10) BF / Y 0.87 0.78
Conditional expression (11) Exp -38.52 -38.58
Conditional expression (12) FD / f 0.95 0.64

According to the present invention, it is possible to provide an optical system and an imaging device having high optical performance and a small size, which can suppress aberration fluctuations during focusing while realizing miniaturization of a focus group. ..

G1 ・ ・ ・ 1st lens group G2 ・ ・ ・ 2nd lens group G2A ・ ・ ・ 2A subgroup G2B ・ ・ ・ 2B subgroup G3 ・ ・ ・ 3rd lens group S ・ ・ ・ Aperture aperture CG ・ ・ ・Cover glass IP ・ ・ ・ Image plane

Claims (13)

It is composed of 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 negative refractive power in order from the object side.
When focusing from an infinity object to a finite distance object, the first lens group and the third lens group are fixed to the image plane, and the second lens group is moved in the optical axis direction.
An optical system characterized by satisfying the following conditional expression (1).
0.40 ≤ G2Fr / f ≤ 0.70 (1)
However,
G2Fr: Radius of curvature of the lens surface on the most object side of the second lens group f: Focal length at infinity focusing of the optical system The optical system according to claim 1, which satisfies the following conditional expression (2).
1.0 ≤ f1 / f2 ≤ 4.0 ... (2)
However,
f1: Focal length of the first lens group f2: Focal length of the second lens group The second lens group is composed of a second A subgroup, an aperture, and a second B subgroup in order from the object side.
The optical system according to claim 1 or 2, which satisfies the following conditional expression (3).
-11 ≤ f2a / f2b ≤ 5.0 ... (3)
However,
f2a: Focal length of the second A subgroup f2b: Focal length of the second B subgroup The second lens group is composed of a second A subgroup, an aperture, and a second B subgroup in order from the object side.
The optical system according to any one of claims 1 to 3, which satisfies the following conditional expression (4).
-2.0 ≤ (R2a + R2b) / (R2a-R2b) ≤ 4.0 ... (4)
However,
R2a: Radius of curvature of the lens surface on the most image side of the second A subgroup R2b: Radius of curvature of the lens surface on the most object side of the second B subgroup The first lens group has at least one lens having a concave shape on the side surface of the object, and among the lenses having a concave shape on the side surface of the object included in the first lens group, the absolute value of the radius of curvature of the side surface of the object is the largest. The optical system according to any one of claims 1 to 4, which has at least one positive lens P1 satisfying the following conditional expression (5) on the image side of the small lens.
ν1 ≤ 30 (5)
However,
ν1: Abbe number on the d line of the positive lens P1 The optical system according to any one of claims 1 to 5, wherein the second lens group has at least one positive lens P2 satisfying the following conditional expression (6).
ν2 ≧ 68 ・ ・ ・ ・ ・ (6)
However,
ν2: Abbe number on the d line of the positive lens P2 The optical system according to any one of claims 1 to 6, which satisfies the following conditional expression (7).
0.60 ≤ f / f2 ≤ 0.85 (7)
However,
f2: Focal length of the second lens group The optical system according to any one of claims 1 to 7, which satisfies the following conditional expression (8).
-45.0 ≤ G1Rr / f ≤ 7.0 ... (8)
However,
G1Rr: Radius of curvature of the lens surface on the image side of the first lens group The optical system according to any one of claims 1 to 8, which satisfies the following conditional expression (9).
-65.0 ≤ G1Fr / f ≤ 6.0 ... (9)
However,
G1Fr: Radius of curvature of the lens surface on the most object side of the first lens group The optical system according to any one of claims 1 to 9, which satisfies the following conditional expression (10).
0.5 ≤ BF / Y ≤ 1.3 ... (10)
However,
BF: Distance on the optical axis from the lens plane on the image side of the third lens group to the image plane Y: Maximum image height of the image plane in the optical system The optical system according to any one of claims 1 to 10, which satisfies the following conditional expression (11).
−45 ≦ Exp <0 ・ ・ ・ ・ ・ (11)
However,
Exp: Exit pupil position of the optical system The optical system according to any one of claims 1 to 11, which satisfies the following conditional expression (12).
0.45 ≤ FD / f ≤ 1.14 (12)
However,
FD: Distance on the optical axis from the most object-side lens surface of the second lens group to the most image-side lens f: Focal length at infinity focusing of the optical system An image pickup apparatus comprising the optical system according to any one of claims 1 to 12 and an image pickup element that converts an optical image formed by the optical system into an electrical signal.

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