JP6969358B2 - Optical system, optical equipment - Google Patents

Description

The present invention relates to an optical system, an optical device, and a method for manufacturing the optical system.

Conventionally, as a focusing method of an optical system, a rear focus method for moving a lens group on the image side of the optical system and an inner focus method for moving an intermediate lens group of the optical system are known (for example, Patent Document 1). reference.). However, in a large-diameter lens having a small open F number and easily generating various aberrations, there is a problem that the aberration fluctuation due to the movement of the lens group is large.

Japanese Unexamined Patent Publication No. 2014-12018

The first aspect of the present invention is
From the object side, it consists of a front group with a positive refractive power, an aperture stop, and a rear group.
The front group includes, in order from the object side, a positive lens group having positive refractive power, and a front case Asegun having positive refractive power,
The posterior group has a posterior focusing group having a positive refractive power.
At the time of focusing, the front focusing group and the rear focusing group move to the object side, the position of the aperture stop is fixed, and the distance between the positive lens group and the front focusing group changes.
An optical system satisfying the following conditional expression is provided.
0.250 <XRF / XFF <1.500
0.010 <fFA / fFF <0.750
However,
XFF: Movement amount of the front focusing group when focusing from an infinity object to a short-distance object XRF: Movement amount of the rear focusing group when focusing from an infinity object to a short-distance object
fFA: Focal length of the positive lens group
fFF: Focal length of the front focusing group

It is sectional drawing of the optical system which concerns on 1st Example. It is a figure of various aberrations of the optical system which concerns on 1st Example. It is sectional drawing of the optical system which concerns on 2nd Example. It is a figure of various aberrations of the optical system which concerns on 2nd Example. It is sectional drawing of the optical system which concerns on 3rd Example. It is a figure of various aberrations of the optical system which concerns on 3rd Example. It is sectional drawing of the optical system which concerns on 4th Embodiment. It is a figure of various aberrations of the optical system which concerns on 4th Embodiment. It is sectional drawing of the optical system which concerns on 5th Embodiment. It is a diagram of various aberrations of an optical system according to a fifth embodiment. It is sectional drawing of the optical system which concerns on 6th Embodiment. 6 is a diagram of various aberrations of the optical system according to the sixth embodiment. It is sectional drawing of the optical system which concerns on 7th Example. It is a diagram of various aberrations of an optical system according to a seventh embodiment. It is sectional drawing of the optical system which concerns on 8th Embodiment. It is a figure of various aberrations of the optical system which concerns on 8th Embodiment. It is sectional drawing of the optical system which concerns on 9th Embodiment. 9 is a diagram of various aberrations of the optical system according to the ninth embodiment. It is sectional drawing of the optical system which concerns on 10th Examples. It is a diagram of various aberrations of an optical system according to a tenth embodiment. It is sectional drawing of the variable magnification optical system which concerns on eleventh embodiment. 11 is a diagram of various aberrations of the wide-angle end state of the variable magnification optical system according to the eleventh embodiment. 11 is a diagram of various aberrations in the telephoto end state of the variable magnification optical system according to the eleventh embodiment. It is a figure which shows the structure of the camera provided with the optical system. It is a figure which shows the outline of the manufacturing method of an optical system.

Hereinafter, an optical system, an optical device, and a method for manufacturing the optical system according to the embodiment will be described.
The optical system of the present embodiment is composed of a front group having a positive refractive power, an aperture throttle, and a rear group in order from the object side, and the front group has a front focusing group having a positive refractive power. However, the posterior group has a posterior focusing group having a positive refractive power, and the anterior focusing group and the posterior focusing group are in focus at least partly from an infinity object to a short-range object. It moves to the object side and satisfies the following conditional expression (1).
(1) 0.250 <XRF / XFF <1.500
However,
XFF: Movement amount of the front focusing group when focusing from an infinity object to a short-distance object XRF: Movement amount of the rear focusing group when focusing from an infinity object to a short-distance object

In the conventional retrofocus type wide-angle lens, when the lens group located on the image side of the aperture stop is the in-focus group, it is necessary to move the in-focus group to the object side in order to suppress the image plane fluctuation.
The optical system of the present embodiment has a configuration in which a positive lens group arranged on the object side of the aperture aperture and a positive lens group arranged on the image side of the aperture aperture are moved to the object side as an in-focus group to perform focusing. It is possible to suppress fluctuations in various aberrations during focusing, and in particular, to satisfactorily correct spherical aberration and curvature of field. Further, by setting two focusing groups, it is possible to reduce the weight of each focusing group and speed up the focusing operation.

The above conditional expression (1) is a conditional expression that defines an appropriate range of the amount of movement of the two focusing groups at the time of focusing. The amount of movement when the in-focus group moves toward the object is positive, and this also applies to the conditional expression (7) described later.

When the corresponding value of the conditional expression (1) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the rear focusing group becomes too large, and spherical aberration, coma aberration, etc. can be sufficiently corrected. It will disappear. In addition, in order to ensure the effect of this embodiment, it is more preferable that the lower limit value of the conditional expression (1) is 0.300, and further preferably 0.350, 0.400, 0.450.

On the other hand, when the corresponding value of the conditional expression (1) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the rear focusing group becomes too small, and sufficient performance is ensured at the time of focusing on a close-range object. This is not possible, and the curvature of field aberration is insufficiently corrected. In addition, in order to ensure the effect of this embodiment, the upper limit of the conditional expression (1) shall be 1.400, and further set to 1.300, 1.200, 1.100, 1.000, 0.900. Is more preferable.

With the above configuration, it is possible to realize an optical system that is suitable for a mirrorless camera and has good optical performance by suppressing fluctuations in various aberrations during focusing while reducing the weight of the focusing group.

Further, in the optical system of the present embodiment, it is desirable that the position of the aperture stop is fixed at the time of focusing. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (2).
(2) 0.400 <Bf / f <2.000
However,
Bf: Distance from the image side lens surface of the lens located closest to the image side when the infinity object is in focus, that is, back focus f: Focal length of the optical system when the infinity object is in focus.

The conditional expression (2) is a conditional expression that defines an appropriate range of the back focus and the focal length of the entire optical system. If there is a parallel flat plate such as a filter in the optical system, the value calculated by replacing it with air is used for Bf in the conditional expression (2). This also applies to ST, TL and Bf in the conditional expressions (3), (6) and (13) described later.

When the corresponding value of the conditional expression (2) of the optical system of the present embodiment exceeds the upper limit value, the back focus becomes large and the telecentricity is maintained, but the entire optical system becomes large. Further, if it is attempted to suppress the increase in the diameter of the front group due to the increase in size, it becomes difficult to correct the distortion aberration and the like. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (2) is 1.900, and further 1.800, 1.700, 1.600, 1.500, 1.400, 1. It is more preferably 300, 1.200 and 1.100.

On the other hand, when the corresponding value of the conditional expression (2) of the optical system of the present embodiment is lower than the lower limit value, the position of the exit pupil is displaced toward the object side. For this reason, shading becomes remarkable, which causes a decrease in resolution especially around the screen. In order to ensure the effect of this embodiment, it is more preferable that the lower limit of the conditional expression (2) is 0.450, and further preferably 0.500, 0.550, 0.600, 0.700.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (3).
(3) 0.100 <ST / TL <0.600
However,
ST: Distance from the aperture stop to the image plane when the object is in focus at infinity TL: Distance from the lens surface on the object side of the lens located on the closest object side to the image plane when the object is in focus at infinity, that is, an optical system Total length of

The above conditional expression (3) is a conditional expression that defines an appropriate range of the distance from the aperture stop to the image plane and the total length of the optical system, and estimates the position of the exit pupil from the position of the aperture stop in the optical system. ..

When the corresponding value of the conditional expression (3) of the optical system of the present embodiment exceeds the upper limit value, the telecentricity is maintained, but the overall length of the optical system becomes large and miniaturization cannot be achieved. Further, if an attempt is made to reduce the diameter of the front group while the total length of the optical system is increased, it becomes difficult to sufficiently correct distortion aberration and the like. In addition, in order to ensure the effect of this embodiment, the upper limit of the conditional expression (3) shall be 0.570, and further set to 0.550, 0.530, 0.500, 0.480, 0.460. Is more preferable.

On the other hand, when the corresponding value of the conditional expression (3) of the optical system of the present embodiment is less than the lower limit value, the aperture stop is arranged closer to the object than the appropriate position. For this reason, the light beam cannot be blocked evenly by the aperture stop, the point image when the aperture is stopped down is distorted, and the limb darkening is deteriorated. In addition, it becomes difficult to correct the chromatic aberration of magnification. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (3) is set to 0.120, and further 0.140, 0.170, 0.200, 0.250, 0.300, 0. It is more preferably 350.

Further, it is desirable that the optical system of this embodiment satisfies the following conditional expression (4).
(4) 0.200 <βRF / βFF <1.10
However,
βFF: Magnification of the anterior focusing group βRF: Magnification of the posterior focusing group

The above conditional expression (4) is a conditional expression that defines the ratio of appropriate magnifications of the front-side focusing group and the rear-side focusing group.

When the corresponding value of the conditional expression (4) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the rear focusing group becomes too large, and spherical aberration, coma aberration, etc. can be sufficiently corrected. It will disappear. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (4) is set to 1.000, and further 0.950, 0.900, 0.850, 0.800, 0.750, 0. It is more preferably 700.

On the other hand, when the corresponding value of the conditional expression (4) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the rear focusing group becomes too small, and the magnification required for focusing cannot be obtained. For this reason, sufficient performance cannot be ensured when the object is focused at a close distance, and the curvature of field aberration is insufficiently corrected. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (4) is set to 0.220, and further 0.240, 0.260, 0.280, 0.300, 0.320, 0.320, 0. It is more preferably 350 or 0.370.

Further, in the optical system of the present embodiment, it is desirable that the position of the lens group located closest to the object side at the time of focusing is fixed. As a result, a good image can be obtained with a small change in image magnification during focusing, and the mechanical configuration of the optical system of the present embodiment can be simplified.

Further, in the optical system of the present embodiment, it is desirable that the position of the lens group located closest to the image side at the time of focusing is fixed. As a result, it is possible to secure a back focus of an appropriate size and a sufficient exit pupil distance, and it is possible to simplify the mechanical configuration of the optical system of the present embodiment.

Further, in the optical system of the present embodiment, it is desirable that the front focusing group has at least one positive lens and at least one negative lens. As a result, various aberrations such as chromatic aberration of magnification can be satisfactorily corrected.

Further, in the optical system of the present embodiment, it is desirable that the rear focusing group has at least one positive lens and at least one negative lens. As a result, various aberrations such as chromatic aberration of magnification can be satisfactorily corrected.

Further, it is desirable that the optical system of the present embodiment has the rear-side focusing group and the negative lens group having a negative refractive power in order from the object side. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed. Further, when the optical system of the present embodiment is mounted on the camera, light can be efficiently guided to the image pickup device.

Further, it is desirable that the optical system of this embodiment satisfies the following conditional expression (5).
(5) 0.800 <(-fRB) /f <10.000
However,
fRB: Focal length of the negative lens group f: Focal length of the optical system when focusing on an object at infinity

The conditional expression (5) is a conditional expression that defines the focal length of the negative lens group and the focal length of the entire optical system.

When the corresponding value of the conditional expression (5) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the negative lens group becomes too small. Therefore, the back focus becomes large and the optical system becomes large. In addition, coma aberration and the like cannot be sufficiently corrected. In order to ensure the effect of this embodiment, it is more preferable that the upper limit of the conditional expression (5) is 9.000, and further preferably 8,000, 7,000, 6,000, and 5.000.

On the other hand, when the corresponding value of the conditional expression (5) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the negative lens group becomes too large. Therefore, it becomes impossible to secure a sufficient exit pupil distance. In addition, distortion aberration and the like cannot be sufficiently corrected. In addition, in order to ensure the effect of this embodiment, the lower limit of the conditional expression (5) is 1.000, and further, 1.200, 1.400, 1.600, 1.800, 2.000. Is more preferable.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (6).
(6) 0.060 <Bf / TL <0.650
However,
Bf: Distance from the image side lens surface of the lens located closest to the image side when the infinity object is in focus TL: From the object side lens surface of the lens located closest to the object side when the infinity object is in focus Distance to the image plane

The conditional expression (6) is a conditional expression that defines the back focus and the total length of the optical system, and estimates the approximate position of the exit pupil. By satisfying the conditional expression (6), the optical system of the present embodiment does not relatively displace the exit pupil toward the image side even if the total length is reduced, which is advantageous for widening and downsizing the optical system. It becomes.

If the corresponding value of the conditional expression (6) of the optical system of the present embodiment exceeds the upper limit value, the back focus becomes too large and the optical system becomes large. Alternatively, the total length of the optical system becomes too small, and it becomes difficult to correct spherical aberration and coma. In addition, in order to ensure the effect of this embodiment, the upper limit of the conditional expression (6) is set to 0.600, and further 0.550, 0.500, 0.480, 0.430, 0.400, 0. More preferably, it is 370 or 0.300.

On the other hand, when the corresponding value of the conditional expression (6) of the optical system of the present embodiment is less than the lower limit value, the position of the exit pupil is too close to the image plane and vignetting of light rays occurs on the image plane. Further, if an attempt is made to avoid this, it may be difficult to correct off-axis aberrations, particularly coma aberrations, which is not preferable. In order to ensure the effect of this embodiment, it is more preferable that the lower limit of the conditional expression (6) is 0.070, and further preferably 0.080, 0.090, 0.100, 0.110.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (7).
(7) 0.010 <XRF / f <0.240
However,
XRF: Movement amount of the rear focusing group when focusing from an infinite object to a short-distance object f: Focal length of the optical system when focusing on an infinite object

The above conditional expression (7) is a conditional expression in which an appropriate range of the amount of movement of the rear focusing group is defined by the focal length of the entire optical system.

When the corresponding value of the conditional expression (7) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the rear focusing group becomes too small, and sufficient performance can be ensured at the time of focusing on a close-range object. This is not possible, and the curvature of field aberration is insufficiently corrected. In order to ensure the effect of this embodiment, it is more preferable that the upper limit of the conditional expression (7) is 0.220, further 0.200, 0.180, 0.150.

On the other hand, when the corresponding value of the conditional expression (7) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the rear focusing group becomes too large, and spherical aberration, coma aberration, etc. are sufficiently corrected. Can no longer be done. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (7) is set to 0.013, and further 0.016, 0.019, 0.022, 0.024, 0.030, 0. It is more preferably 040 or 0.050.

Further, in the optical system of the present embodiment, it is desirable that the lens located closest to the object side has a negative refractive power. In this way, even though it is a retrofocus type, by making the refractive power of the entire front group positive, it is possible to reduce the diameter of the lens group on the most object side while ensuring a large angle of view, and secure an appropriate back focus. However, the total length can be shortened.

Further, in the optical system of the present embodiment, it is desirable that the rear group has a positive refractive power. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (8).
(8) 0.010 <fRF / fFF <0.990
However,
fFF: Focal length of the anterior focusing group fRF: Focal length of the posterior focusing group

The above conditional expression (8) describes the appropriate refractive power distribution of the two focusing groups by the ratio of the focal lengths.

When the corresponding value of the conditional expression (8) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the front focusing group becomes too small. For this reason, the front focusing group has an excessively large stroke during focusing and interferes with the positive lens group. Alternatively, the curvature of field aberration cannot be sufficiently corrected. In order to ensure the effect of this embodiment, it is more preferable to set the lower limit of the conditional expression (8) to 0.015, further preferably 0.020 or 0.024.

On the other hand, when the corresponding value of the conditional expression (8) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the rear focusing group becomes too large. Therefore, it becomes difficult to correct spherical aberration and the like. In order to ensure the effect of this embodiment, it is more preferable that the upper limit of the conditional expression (8) is 0.700, and further preferably 0.500, 0.400, 0.300, 0.250.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (9).
(9) 0.300 <fF / fR <1.300
However,
fF: Focal length of the front group when focusing on an infinity object fR: Focal length of the rear group when focusing on an infinity object

The above conditional expression (9) is a conditional expression that defines an appropriate refractive power distribution between the front group and the rear group.

If the corresponding value of the conditional equation (9) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the rear group becomes too large, and spherical aberration, coma aberration, etc. cannot be sufficiently corrected. .. In addition, in order to ensure the effect of this embodiment, the upper limit of the conditional expression (9) is set to 1.200, and further 1.150, 1.100, 1.050, 1.000, 0.950, 0. More preferably, it is 900, 0.850, 0.800.

On the other hand, when the corresponding value of the conditional expression (9) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the rear group becomes too small and the magnification required for focusing cannot be obtained. For this reason, sufficient performance cannot be ensured when the object is focused at a close distance, and the curvature of field aberration is insufficiently corrected. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (9) is set to 0.330, and further 0.350, 0.380, 0.400, 0.430, 0.450, 0. More preferably, it is 480 or 0.500.

Further, in the optical system of the present embodiment, it is desirable that the front group has a positive lens group having a positive refractive power and a front focusing group in order from the object side. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed.

Further, it is desirable that the optical system of this embodiment satisfies the following conditional expression (10).
(10) 0.010 <fFA / fFF <0.750
However,
fFA: Focal length of the positive lens group fFF: Focal length of the front focusing group

The above conditional expression (10) is a conditional expression that defines the focal length of the front focusing group and the focal length of the positive lens group.

If the corresponding value of the conditional expression (10) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the front focusing group becomes too large, and it becomes difficult to correct the chromatic aberration of magnification or the like. In addition, in order to ensure the effect of this embodiment, the upper limit of the conditional expression (10) is set to 0.700, and further 0.650, 0.600, 0.550, 0.500, 0.450, 0. More preferably, it is 400, 0.350, 0.300, 0.250.

On the other hand, when the corresponding value of the conditional expression (10) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the front focusing group becomes too small, and it becomes difficult to correct the curvature of field aberration and the like. It ends up. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (10) is set to 0.015, and further 0.020, 0.025, 0.030, 0.035, 0.040, 0. More preferably, it is 045, 0.050, 0.060, 0.070, 0.080.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (11).
(11) 0.010 <f / fFF <0.300
However,
f: Focal length of the optical system when focusing on an infinite object fFF: Focal length of the front focusing group

The conditional expression (11) is a conditional expression that defines the focal length of the front focusing group and the focal length of the entire optical system.

If the corresponding value of the conditional expression (11) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the front focusing group becomes too large, and it becomes difficult to correct the chromatic aberration of magnification or the like. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (11) is set to 0.280, and further 0.250, 0.230, 0.200, 0.180, 0.160, 0. More preferably, it is 140, 0.120, 0.100, 0.080.

On the other hand, when the corresponding value of the conditional expression (11) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the front focusing group becomes too small, and it becomes difficult to correct the curvature of field aberration and the like. It ends up. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (11) is set to 0.012, and further 0.014, 0.016, 0.017, 0.020, 0.025, 0. It is more preferably 030 or 0.035.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (12).
(12) 0.300 <f / fRF <1.10
However,
f: Focal length of the optical system when focusing on an infinite object fRF: Focal length of the rear focusing group

The conditional expression (12) is a conditional expression that defines the focal length of the rear focusing group and the focal length of the entire optical system.

When the corresponding value of the conditional expression (12) of the optical system of the present embodiment exceeds the upper limit value, the refractive power of the rear focusing group becomes too small. For this reason, the stroke of the rear focusing group at the time of focusing becomes large, and the optical system becomes large. Alternatively, the curvature of field aberration cannot be sufficiently corrected. In order to ensure the effect of this embodiment, it is more preferable that the upper limit of the conditional expression (12) is 1.050, and further preferably 1.000, 0.950, 0.900, 0.850.

On the other hand, if the corresponding value of the conditional expression (12) of the optical system of the present embodiment is less than the lower limit value, the refractive power of the rear focusing group becomes too large, and it becomes difficult to correct spherical aberration and the like. .. In addition, in order to ensure the effect of this embodiment, the lower limit of the conditional expression (12) shall be 0.350, and further set to 0.400, 0.450, 0.500, 0.550, 0.600. Is more preferable.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (13).
(13) 0.800 <TL / (Fno ・ Bf) <6.60
However,
TL: Distance from the lens surface to the image plane of the lens located on the most object side when the object is in focus at infinity Fno: Open F number Bf of the optical system: To the image side when the object is in focus at infinity Distance from the image side lens surface of the located lens to the image surface

The conditional expression (13) is a conditional expression showing the optimum balance between the total length of the optical system and the back focus in order to make the optical system a bright wide-angle lens.

If the corresponding value of the conditional expression (13) of the optical system of the present embodiment exceeds the upper limit value, the total length of the optical system increases and the optical system becomes large. Alternatively, since the F number becomes small, it becomes difficult to correct the spherical aberration. In addition, in order to ensure the effect of this embodiment, the upper limit of the conditional expression (13) is set to 5.500, and further, 5.000, 4.500, 4.300, 4.100, 4.000, 3. It is more preferably 800 and 3.600.

On the other hand, if the corresponding value of the conditional expression (13) of the optical system of the present embodiment is less than the lower limit value, the total length of the optical system becomes too small, and it becomes difficult to correct coma aberration and the like. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (13) is set to 0.900, and further 1.000, 1.100, 1.300, 1.500, 1.800, 2. More preferably, it is 000, 2.200, or 2.500.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (14).
(14) | Ainf-Amod | / f <0.070
However,
Ainf: Half angle of view of the optical system when focusing on an infinity object (unit is "°")
Amod: Half angle of view of the optical system when the closest object is in focus (unit is "°")

The above conditional expression (14) is a conditional expression that defines the ratio of the incident ray angle at the time of focusing on an infinite object and the incident light angle at the time of focusing on the nearest object, and estimates the change in the image magnification at the time of focusing. Is.

If the corresponding value of the conditional expression (14) of the optical system of the present embodiment exceeds the upper limit value, the image magnification changes at the time of focusing, and a good image cannot be obtained. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (14) is 0.065, and further, 0.060, 0.055, 0.050, 0.045, 0.040. Is more preferable.

Further, in the optical system of the present embodiment, the front focusing group includes one positive lens and one negative lens, and it is desirable that the following conditional expression (15) is satisfied.
(15) 30.00 <νFFp-νFFn <75.00
However,
νFFp: Abbe number with respect to the d-line (λ = 587.6 nm) of the positive lens in the front focusing group νFFn: Abbe number with respect to the d-line (λ = 587.6 nm) of the negative lens in the front focusing group

The conditional expression (15) is a relational expression of the dispersion of the positive lens and the negative lens included in the front focusing group. The optical system of the present embodiment can satisfactorily correct chromatic aberration by satisfying the conditional expression (15).

In order to ensure the effect of the present embodiment, it is more preferable that the upper limit of the conditional expression (15) is 70.00, and further preferably 65.00, 61.00, 58.00, 56.00.

In order to ensure the effect of this embodiment, it is more preferable that the lower limit of the conditional expression (15) is 35.00, further 40.00, 45.00, and 50.00.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (16).
(16) -1,000 <(FFr2 + FFr1) / (FFr2-FFr1) <2.000
However,
FFr1: Radius of curvature of the object-side lens surface of the positive lens located most on the image side in the front focusing group FFr2: Curvature radius of the image-side lens surface of the positive lens located on the image side of the front focusing group

The conditional expression (16) is a conditional expression that defines the shape factor of the positive lens located on the image side most in the front focusing group.

When the corresponding value of the conditional expression (16) of the optical system of the present embodiment exceeds the upper limit value, the curvature of the lens surface on the object side of the positive lens becomes large and it becomes difficult to correct the spherical aberration. In addition, in order to ensure the effect of this embodiment, the upper limit of the conditional expression (16) is 1.500, and further 1.300, 1.000, 0.900, 0.800, 0.700, 0. It is more preferably 600.

On the other hand, if the corresponding value of the conditional expression (16) of the optical system of the present embodiment is less than the lower limit value, it becomes difficult to correct coma aberration and the like. In addition, in order to ensure the effect of this embodiment, the lower limit of the conditional expression (16) shall be -0.800, and further set to -0.600, -0.400, -0.200, 0.000. Is more preferable.

Further, in the optical system of the present embodiment, it is desirable that the front focusing group consists of two or three lenses. As a result, the weight of the front focusing group can be reduced and the autofocus speed can be increased.

Further, it is desirable that the optical system of the present embodiment comprises a lens having four or less rear focusing groups. As a result, it is possible to reduce the weight of the rear focusing group and achieve high-speed autofocus.

Further, in the optical system of the present embodiment, it is desirable that the lens group located closest to the image side has a positive lens and a negative lens in order from the image side. This makes it possible to secure an appropriately sized back focus and a sufficient exit pupil distance.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expression (17).
(17) 0.030 <nRBp-nRBn
However,
nRBp: Refractive index with respect to the d-line (λ = 587.6 nm) of the positive lens in the lens group located most on the image side nRBn: d-line (λ = 587.6 nm) of the negative lens in the lens group located on the image side most ) Refractive index

The conditional expression (17) is a conditional expression that defines the difference in refractive index between the positive lens and the negative lens in the lens group located closest to the image side.
If the corresponding value of the conditional expression (17) of the optical system of the present embodiment is less than the lower limit value, the Petzval sum cannot be corrected, and an appropriate exit pupil distance and back focus cannot be maintained. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (17) is set to 0.040, and further 0.050, 0.060, 0.070, 0.080, 0.090, 0. It is more preferably 100.

Further, in the optical system of the present embodiment, it is desirable that the image side lens surface of the lens located on the image side in the lens group located on the image side is convex toward the image side. This makes it possible to secure an appropriate exit pupil distance and back focus.

Further, it is desirable that the optical system of the present embodiment satisfies the following conditional expressions (18) and (19).
(18) 1.000 <nRBp + 0.005νRBp <2.500
(19) 1.000 <nRBn + 0.005νRBn <2.500
However,
nRBp: Refractive coefficient with respect to the d-line (λ = 587.6 nm) of the positive lens in the lens group located most on the image side nRBn: d-line (λ = 587.6 nm) of the negative lens in the lens group located on the image side most ) With respect to refractive index νRBp: d-line of the positive lens in the lens group located most on the image side (λ = 587.6 nm) Abbe number νRBn: d-line of the negative lens in the lens group located on the image side most = 587.6 nm) Abbe number

The conditional expression (18) is a conditional expression that defines the relationship between the refractive index and the dispersion of the positive lens included in the lens group located closest to the image side. The optical system of the present embodiment can satisfactorily correct chromatic aberration by satisfying the conditional expression (18).

In addition, in order to ensure the effect of this embodiment, it is more preferable that the upper limit value of the conditional expression (18) is 2.400, and further preferably 2.300, 2.200, 2.100.

In order to ensure the effect of this embodiment, it is more preferable that the lower limit of the conditional expression (18) is 1.200, and further preferably 1.400, 1.600, and 1.800.

The conditional expression (19) is a conditional expression that defines the relationship between the refractive index and the dispersion of the negative lens included in the lens group located closest to the image side. The optical system of the present embodiment can satisfactorily correct chromatic aberration by satisfying the conditional expression (19).

In order to ensure the effect of this embodiment, it is more preferable that the upper limit of the conditional expression (19) is 2.400, and further preferably 2.300, 2.200, 2.100.

In order to ensure the effect of this embodiment, it is more preferable that the lower limit of the conditional expression (19) is 1.200, and further preferably 1.400, 1.600, and 1.800.

Further, in the optical system of the present embodiment, it is desirable that the front focusing group and the aperture stop are adjacent to each other. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed.

Further, in the optical system of the present embodiment, it is desirable that the aperture stop and the rear focusing group are adjacent to each other. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed.

Further, in the optical system of the present embodiment, it is desirable that the front group further has a lens group whose position is fixed at the time of focusing between the front side focusing group and the aperture diaphragm. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed.

Further, in the optical system of the present embodiment, it is desirable that the rear group further has a lens group whose position is fixed at the time of focusing between the aperture stop and the rear focusing group. As a result, various aberrations such as spherical aberration and curvature of field aberration can be satisfactorily corrected, and fluctuations in the various aberrations at the time of focusing can be suppressed.

The optical device of the embodiment has an optical system having the above-described configuration. This makes it possible to realize an optical device that is suitable for a mirrorless camera and has good optical performance by suppressing fluctuations in various aberrations during focusing while reducing the weight of the focusing group.

The method for manufacturing an optical system according to an embodiment is a method for manufacturing an optical system including a front group having a positive refractive power, an aperture throttle, and a rear group in order from the object side, and the front group has positive refractive power. The front focusing group has a force, the rear group has a rear focusing group having a positive refractive power, and the front focusing group and the rear focusing group are on the object side at the time of focusing. It is moved so that the front-side focusing group and the rear-side focusing group satisfy the following conditional expression (1). This makes it possible to manufacture an optical system that is suitable for a mirrorless camera and has good optical performance by suppressing fluctuations in various aberrations during focusing while reducing the weight of the focusing group.
(1) 0.250 <XRF / XFF <1.500
However,
XFF: Movement amount of the front focusing group when focusing from an infinity object to a short-distance object XRF: Movement amount of the rear focusing group when focusing from an infinity object to a short-distance object

Hereinafter, examples relating to the optical system of the embodiment will be described with reference to the accompanying drawings.
(First Example)
1 (a) and 1 (b) are cross-sectional views of the optical system according to the first embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the first embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA consists of a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, a biconvex positive lens L3, and a biconcave lens in order from the object side. It is composed of a junction lens of a negative lens L4 and a biconvex positive lens L5, and a biconvex positive lens L6.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a negative meniscus lens L9 having a convex surface facing the image side and a biconvex positive lens L10 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L11 and a plano-convex positive lens L12 having a convex surface facing the object side in order from the object side.

In the optical system according to the first embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved toward the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.

Table 1 below lists the values of the specifications of the optical system according to the first embodiment.
In Table 1, f indicates a focal length, and Bf indicates a back focus (distance on the optical axis between the lens surface on the image side and the image surface I).
In [plane data], the plane number is the order of the optical planes counted from the object side, r is the radius of curvature, d is the plane spacing (distance between the nth plane (n is an integer) and the n + 1th plane), and nd is. The refractive index for the d-line (wavelength 587.6 nm) and νd indicate the Abbe number for the d-line (wavelength 587.6 nm). Further, the object surface is an object surface, the variable is a variable surface interval, the aperture S is an aperture stop S, and the image surface is an image surface I. The radius of curvature r = ∞ indicates a plane. For the aspherical surface, "*" is added to the surface number and the value of the paraxial radius of curvature is shown in the column of radius of curvature r.

[Aspherical surface data] shows the aspherical surface coefficient and the conical constant when the shape of the aspherical surface shown in [Surface data] is expressed by the following equation.
x = (h ² / r) / [1 + {1-κ (h / r) ² } ^1/2 ] + A4h ⁴ + A6h ⁶ + A8h ⁸
Here, h is the height in the direction perpendicular to the optical axis, x is the distance (sag amount) along the optical axis direction from the tangent plane of the apex of the aspherical surface to the aspherical surface at height h, and κ is the conical constant. , A4, A6, A8 are the aspherical surface coefficients, and r is the radius of curvature of the reference sphere (near-axis radius of curvature). In addition, "E −n" (n is an integer) indicates “× 10 ⁻ⁿ ”, and for example, “1.23456E-07” indicates “1.23456 × 10 ⁻⁷ ”. The second-order aspherical coefficient A2 is 0, and the description is omitted.

In [Various data], Fno is the F number, 2ω is the angle of view (unit is "°"), ω is the half angle of view (unit is "°"), Ymax is the maximum image height, β is the closest shooting magnification, and TL is. The total length of the optical system according to the first embodiment (distance on the optical axis from the first plane to the image plane I) and dn indicate variable intervals between the nth plane and the n + 1th plane. The air-converted Bf and the air-converted TL indicate Bf and TL obtained by converting the thickness of the filter F into air, respectively. Ainf indicates the half-angle of view when focusing on an infinity object, and Amod indicates the half-angle of view when focusing on the nearest object (both units are "°"). Note that infinity indicates the time of focusing on an infinity object, and short distance indicates the time of focusing on a short-distance object.
[Lens group data] shows the start surface and focal length of each lens group.
[Conditional expression corresponding value] indicates the corresponding value of each conditional expression of the optical system according to the first embodiment.

Here, "mm" is generally used as the unit of the focal length f, the radius of curvature r and other lengths shown in Table 1. However, the optical system is not limited to this because the same optical performance can be obtained even if the optical system is proportionally expanded or contracted.
The reference numerals in Table 1 described above shall be used in the same manner in the tables of the respective examples described later.

(Table 1) First Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 85.0000 2.7000 1.744000 44.80
2) 25.0533 9.4392 1.000000
3) 54.7416 2.0000 1.588870 61.13
* 4) 18.4256 10.7082 1.000000
5) 516.8640 3.7787 1.903658 31.31
6) -114.1419 3.5370 1.000000
7) -50.2377 2.0000 1.620040 36.40
8) 30.6947 10.4006 1.851500 40.78
9) -261.5465 0.2000 1.000000
10) 41.0143 5.7649 1.851500 40.78
11) -317.4121 Variable 1.000000
12) (Virtual surface) ∞ 0.0000 1.000000
13) 56.6941 4.1550 1.497820 82.57
14) -64.4398 1.2000 1.808090 22.74
15) 364.1222 Variable 1.000000
16) (Aperture S) ∞ Variable 1.000000
* 17) -38.5516 1.4869 1.860999 37.10
* 18) -43.3477 1.3930 1.000000
19) 54.9022 6.5932 1.497820 82.57
20) -18.1086 Variable 1.000000
* 21) -26.4619 1.4000 1.689480 31.02
22) 48.9165 2.3305 1.000000
* 23) 39.3225 3.4184 1.832199 40.10
24) ∞ 17.1751 1.000000
25) ∞ 1.6000 1.516800 64.13
26) ∞ 0.9931 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
4 0.0000 8.15384E-06 -6.41018E-09 3.11521E-11 -7.69764E-14 0.67523E-16
17 0.0000 -3.75535E-05 4.12683E-08 9.77350E-10 -1.51945E-11 0.24817E-13
18 1.0000 7.81937E-06 1.19209E-07 1.46234E-09 -1.69623E-11 0.50939E-13
21 1.5918 1.17009E-04 -7.89642E-07 5.72645E-09 -2.68019E-11 0.55035E-13
23 1.0000 -7.49387E-05 4.05516E-07 -2.44584E-09 8.81114E-12 -0.14105E-13
[Various data]
f 20.1396
Fno 1.85813
2ω 96.9415
Ymax 21.60
TL 113.97307
Air conversion TL 113.42787
Bf 19.7682
Air conversion Bf 19.223
Ainf 49.11334
Amod 48.15531
Point at infinity short distance f 20.1396
β -0.1886
d0 ∞ 86.0518
d11 6.6882 3.2619
d15 4.1566 7.5829
d16 7.3258 5.5189
d20 3.5287 5.3356
2ω 96.9415
ω 48.4707
[Lens group data]
Group starting surface f
GF 1 41.6168
GR 17 56.1686
GFA 1 50.4642
GFF 12 519.7498
GRF 17 29.1224
GRB 21 -59.3852
[Conditional expression correspondence value]
(1) XRF / XFF = 0.5274
(2) Bf / f = 0.9545
(3) ST / TL = 0.4500
(4) βRF / βFF = 0.3989
(5) (-fRB) /f=2.9486
(6) Bf / TL = 0.1695
(7) XRF / f = 0.0897
(8) fRF / fFF = 0.0560
(9) fF / fR = 0.7409
(10) fFA / fFF = 0.0971
(11) f / fFF = 0.0387
(12) f / fRF = 0.6916
(13) TL / (Fno ・ Bf) = 3.1756
(14) | Ainf-Amod | / f = 0.0476
(15) νFFp-νFFn = 59.8300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.0639
(17) nRBp-nRBn = 0.1427
(18) nRBp + 0.005νRBp = 2.0327
(19) nRBn + 0.005νRBn = 1.8446

2 (a) and 2 (b) are aberration diagrams of the optical system according to the first embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.

In each aberration diagram, FNO indicates F number, Y indicates image height, and NA indicates numerical aperture. Specifically, the spherical aberration diagram shows the value of the F number FNO or the numerical aperture NA corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum value of the image height Y, and the coma aberration diagram shows each image height. Indicates the value of. Further, in each aberration diagram, d indicates an aberration at the d line (wavelength 587.6 nm), and g indicates an aberration at the g line (wavelength 435.8 nm). In the astigmatism diagram, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. The coma aberration diagram shows coma aberration at each image height Y. In the aberration diagram of each embodiment described later, the same reference numerals as those of this embodiment are used.

From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(Second Example)
3 (a) and 3 (b) are cross-sectional views of the optical system according to the second embodiment at the time of focusing on an infinite object and the time of focusing on a short-range object, respectively.
The optical system according to the second embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA consists of a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, a biconvex positive lens L3, and a biconcave lens in order from the object side. It is composed of a junction lens of a negative lens L4 and a positive meniscus lens L5 having a convex surface facing the object side, and a biconvex positive lens L6.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.

The rear group GR is composed of a negative lens group GRA having a negative refractive power, a rear focusing group GRF having a positive refractive power, and a negative lens group GRB having a negative refractive power in order from the object side.
The negative lens group GRA is composed of a negative meniscus lens L9 having a convex surface facing the object side.
The rear focusing group GRF is composed of a positive meniscus lens L10 having a convex surface facing the image side and a biconvex positive lens L11 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L12 and a plano-convex positive lens L13 having a convex surface facing the object side in order from the object side.

In the optical system according to the second embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved to the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S, the negative lens group GRA, and the negative lens group GRB are fixed.
Table 2 below lists the values of the specifications of the optical system according to the second embodiment.

(Table 2) Second Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 89.6637 2.3000 1.744000 44.80
2) 29.1933 8.8855 1.000000
3) 80.9611 2.0000 1.588870 61.13
* 4) 18.6119 11.2072 1.000000
5) 363.7622 4.9254 1.903658 31.31
6) -101.1501 2.7468 1.000000
7) -54.6987 5.0000 1.620040 36.40
8) 32.2537 8.4862 1.851500 40.78
9) 1296.4983 0.2000 1.000000
10) 45.2794 5.9980 1.851500 40.78
11) -141.1734 Variable
12) (Virtual surface) ∞ 0.0000 1.000000
13) 41.5816 4.4074 1.497820 82.57
14) -76.5015 1.2000 1.808090 22.74
15) 129.2012 Variable
16) (Aperture S) ∞ 2.0000 1.000000
17) 340.8668 1.2000 1.487490 70.32
18) 102.2210 variable
* 19) -96.3223 2.0483 1.860999 37.10
20) -78.6357 1.3930 1.000000
21) 60.1667 7.9457 1.497820 82.57
22) -18.5027 Variable
* 23) -27.6858 1.3000 1.689480 31.02
24) 44.6169 1.9137 1.000000
* 25) 37.7956 2.4912 1.832199 40.10
26) ∞ 16.6751 1.000000
27) ∞ 1.6000 1.516800 63.88
28) ∞ 1.0000 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
4 0.0000 8.02959E-06 2.44201E-09 1.15819E-11 -5.28374E-15 0.20308E-16
19 0.0000 -3.96671E-05 -9.87679E-08 2.89585E-11 -4.23597E-12 -0.17965E-15
23 1.5084 1.22824E-04 -8.31232E-07 5.29431E-09 -2.14010E-11 0.35630E-13
25 1.0000 -8.30036E-05 4.42223E-07 -2.36224E-09 7.62005E-12 -0.96482E-14
[Various data]
f 20.4000
Fno 1.86668
2ω 96.1606
Ymax 21.60
TL 117.00851
Air conversion TL 116.46331
Bf 19.27514
Air conversion Bf 18.72994
Ainf 18.75122
Amod 47.95116
Point at infinity short distance f 20.4000
β -0.1896
d0 ∞ 86.3709
d11 5.7481 2.6300
d15 4.1550 7.2731
d18 6.4768 4.6001
d22 3.7053 5.5821
2ω 96.1606
ω 48.0803
[Lens group data]
Group starting surface f
GF 1 41.2883
GR 19 54.7498
GFA 1 51.4084
GFF 12 485.7773
GRA 16 -300.0000
GRF 19 27.7405
GRB 23 -60.6065
[Conditional expression correspondence value]
(1) XRF / XFF = 0.6019
(2) Bf / f = 0.9181
(3) ST / TL = 0.4225
(4) βRF / βFF = 0.3322
(5) (-fRB) /f=2.9709
(6) Bf / TL = 0.16082
(7) XRF / f = 0.0920
(8) fRF / fFF = 0.0571
(9) fF / fR = 0.7451
(10) fFA / fFF = 0.1058
(11) f / fFF = 0.0420
(12) f / fRF = 0.7354
(13) TL / (Fno ・ Bf) = 3.3311
(14) | Ainf-Amod | / f = 0.0392
(15) νFFp-νFFn = 59.8300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.2957
(17) nRBp-nRBn = 0.1427
(18) nRBp + 0.005νRBp = 2.0327
(19) nRBn + 0.005νRBn = 1.8446

4 (a) and 4 (b) are aberration diagrams of the optical system according to the second embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(Third Example)
5 (a) and 5 (b) are cross-sectional views of the optical system according to the third embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the third embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power, a front focusing group GFF having a positive refractive power, and a positive lens group GFB having a positive refractive power in order from the object side.
The positive lens group GFA includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the image side. It is composed of a junction lens of a biconcave negative lens L4 and a biconvex positive lens L5, and a biconvex positive lens L6.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.
The positive lens group GFB is composed of a plano-convex positive lens L9 having a convex surface facing the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a negative meniscus lens L10 having a convex surface facing the image side and a biconvex positive lens L11 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L12 and a plano-convex positive lens L13 having a convex surface facing the object side in order from the object side.

In the optical system according to the third embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved to the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the positive lens group GFB, the aperture stop S and the negative lens group GRB are fixed.
Table 3 below lists the values of the specifications of the optical system according to the third embodiment.

(Table 3) Third Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 97.1220 2.5000 1.744000 44.80
2) 25.5141 8.5243 1.000000
3) 54.3787 2.0000 1.588870 61.13
* 4) 19.3078 12.0516 1.000000
5) -2541.0384 4.4832 1.903658 31.31
6) -89.4461 3.2029 1.000000
7) -55.7529 4.8378 1.620040 36.40
8) 31.5163 8.0322 1.851500 40.78
9) -603.1050 0.2000 1.000000
10) 44.5738 5.5569 1.851500 40.78
11) -295.5770 Variable 1.000000
12) (Virtual surface) ∞ 0.0000 1.000000
13) 56.3391 4.1355 1.497820 82.57
14) -77.0418 2.0843 1.808090 22.74
15) 274.8271 Variable 1.000000
16) 150.0000 1.6000 1.487490 70.32
17) ∞ 2.0000 1.000000
18) (Aperture S) ∞ Variable 1.000000
* 19) -43.8243 1.2000 1.860999 37.10
20) -57.8611 1.3930 1.000000
21) 70.5507 6.9944 1.497820 82.57
22) -17.1866 Variable 1.000000
* 23) -32.2891 1.3000 1.689480 31.02
24) 34.1671 2.2422 1.000000
25) 37.1466 3.3825 1.832199 40.10
26) ∞ 16.2621 1.000000
27) ∞ 1.6000 1.516800 63.88
28) ∞ 1.0000 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
4 0.0000 6.01620E-06 6.79387E-09 -4.02993E-11 1.20323E-13 -0.15113E-15
19 0.0000 -4.87007E-05 -8.95876E-08 -3.14165E-10 -2.43481E-12 -0.23860E-13
23 5.5636 1.08484E-04 -7.41132E-07 6.01375E-09 -3.07989E-11 0.79304E-13
25 1.0000 -6.01745E-05 3.38304E-07 -1.58920E-09 5.05882E-12 -0.65680E-14
[Various data]
f 20.2698
Fno 1.84435
2ω 96.5219
Ymax 21.60
TL 116.60345
Air conversion TL 116.05825
Bf 18.86209
Air conversion Bf 18.31689
Ainf 48.94839
Amod 48.37479
Point at infinity short distance f 20.2698
β -0.1902
d0 ∞ 85.4430
d11 5.6165 2.4956
d15 2.2463 5.3672
d18 8.5521 6.5490
d22 3.6056 5.6088
2ω 96.5219
ω 48.2609
[Lens group data]
Group starting surface f
GF 1 34.2040
GR 17 66.9283
GFA 1 54.0606
GFF 12 486.5933
GFB 16 307.6986
GRF 19 31.4696
GRB 23 -58.8568
[Conditional expression correspondence value]
(1) XRF / XFF = 0.6418
(2) Bf / f = 0.9037
(3) ST / TL = 0.4049
(4) βRF / βFF = 0.5105
(5) (-fRB) /f=2.9037
(6) Bf / TL = 0.1578
(7) XRF / f = 0.0988
(8) fRF / fFF = 0.0647
(9) fF / fR = 0.5111
(10) fFA / fFF = 0.1111
(11) f / fFF = 0.0417
(12) f / fRF = 0.6441
(13) TL / (Fno ・ Bf) = 3.4354
(14) | Ainf-Amod | / f = 0.0283
(15) νFFp-νFFn = 59.8300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.1552
(17) nRBp-nRBn = 0.1427
(18) nRBp + 0.005νRBp = 2.0327
(19) nRBn + 0.005νRBn = 1.8446

6 (a) and 6 (b) are aberration diagrams of the optical system according to the third embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(Fourth Example)
7 (a) and 7 (b) are cross-sectional views of the optical system according to the fourth embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the fourth embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the image side. It is composed of a junction lens of a biconcave negative lens L4 and a biconvex positive lens L5, and a biconvex positive lens L6.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a positive meniscus lens L9 having a convex surface facing the image side and a biconvex positive lens L10 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L11 and a plano-convex positive lens L12 having a convex surface facing the object side in order from the object side.

In the optical system according to the fourth embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved toward the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.
Table 4 below lists the values of the specifications of the optical system according to the fourth embodiment.

(Table 4) Fourth Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 105.1730 2.5000 1.717000 47.97
2) 28.0761 6.9819 1.000000
3) 54.1318 2.0000 1.568830 56.00
* 4) 19.1358 12.2439 1.000000
5) -1386.9567 3.2295 1.903658 31.31
6) -106.4455 2.3599 1.000000
7) -63.4529 3.3027 1.620040 36.40
8) 29.5793 7.1269 1.851500 40.78
9) -2671.7190 2.3092 1.000000
10) 42.2306 5.3571 1.851500 40.78
11) -303.1326 Variable 1.000000
12) (Virtual surface) ∞ 0.0000 1.000000
13) 58.1267 4.5140 1.497820 82.57
14) -67.7518 2.5150 1.808090 22.74
15) 464.6438 Variable 1.000000
16) (Aperture S) ∞ Variable 1.000000
* 17) -58.9498 2.0443 1.860999 37.10
18) -56.5635 1.3930 1.000000
19) 119.9079 7.3545 1.497820 82.57
20) -17.3792 Variable 1.000000
* 21) -27.6859 1.3000 1.689480 31.02
22) 41.8186 1.7994 1.000000
* 23) 39.3203 3.4174 1.808350 40.55
24) ∞ 18.4523 1.000000
25) ∞ 1.6000 1.516800 64.13
26) ∞ 0.9866 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
4 0.0000 1.01451E-05 3.09662E-10 2.61797E-11 -5.26695E-14 0.49110E-16
17 0.0000 -4.44232E-05 -7.92259E-08 -9.22854E-10 6.75991E-12 -0.57395E-13
21 2.0933 1.10413E-04 -7.62492E-07 5.30334E-09 -2.25140E-11 0.40859E-13
23 1.0000 -7.16079E-05 4.39983E-07 -2.36885E-09 7.66187E-12 -0.10235E-13
[Various data]
f 23.0000
Fno 1.85172
2ω 90.6552
Ymax 21.60
TL 114.98658
Air conversion TL 114.44138
Bf 21.03884
Air conversion Bf 20.49364
Ainf 45.31854
Amod 44.51854
Point at infinity short distance f 23.0000
β -0.1828
d0 ∞ 104.9388
d11 5.9052 2.4996
d15 4.0403 7.4460
d16 8.5116 6.6677
d20 3.7419 5.5858
2ω 90.6552
ω 45.3276
[Lens group data]
Group starting surface f
GF 1 44.7746
GR 17 64.6935
GFA 1 57.4905
GFF 12 413.4387
GRF 17 29.9133
GRB 21 -52.0504
[Conditional expression correspondence value]
(1) XRF / XFF = 0.5414
(2) Bf / f = 0.8910
(3) ST / TL = 0.4374
(4) βRF / βFF = 0.4327
(5) (-fRB) /f=2.2631
(6) Bf / TL = 0.1791
(7) XRF / f = 0.0802
(8) fRF / fFF = 0.0724
(9) fF / fR = 0.6921
(10) fFA / fFF = 0.1391
(11) f / fFF = 0.0556
(12) f / fRF = 0.7689
(13) TL / (Fno ・ Bf) = 3.0157
(14) | Ainf-Amod | / f = 0.0348
(15) νFFp-νFFn = 59.8300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.0765
(17) nRBp-nRBn = 0.1189
(18) nRBp + 0.005νRBp = 2.0111
(19) nRBn + 0.005νRBn = 1.8446

8 (a) and 8 (b) are aberration diagrams of the optical system according to the fourth embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(Fifth Example)
9 (a) and 9 (b) are cross-sectional views of the optical system according to the fifth embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the fifth embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the image side. It is composed of a junction lens of a biconcave negative lens L4 and a biconvex positive lens L5, and a biconvex positive lens L6.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a positive meniscus lens L9 having a convex surface facing the image side and a biconvex positive lens L10 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L11 and a plano-convex positive lens L12 having a convex surface facing the object side in order from the object side.

In the optical system according to the fifth embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved toward the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.
Table 5 below lists the values of the specifications of the optical system according to the fifth embodiment.

(Table 5) Fifth Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 397.0808 2.5000 1.655234 44.96
2) 41.1626 4.3963 1.000000
3) 63.8851 2.0000 1.556354 55.30
* 4) 19.8504 11.8696 1.000000
5) -335.9120 3.4498 1.891325 32.78
6) -92.0502 2.6562 1.000000
7) -66.8872 1.9012 1.620040 36.40
8) 29.5548 8.8222 1.851500 40.78
9) -2141.5083 1.8071 1.000000
10) 44.7902 5.3588 1.851500 40.78
11) -299.4337 Variable 1.000000
12) (Virtual surface) ∞ 0.0000 1.000000
13) 44.5714 5.4239 1.497820 82.57
14) -78.9223 2.8047 1.805180 25.45
15) 160.0738 Variable 1.000000
16) (Aperture S) ∞ Variable 1.000000
* 17) -46.7376 2.0809 1.860999 37.10
18) -42.7565 1.3930 1.000000
19) 262.5587 7.2654 1.497820 82.57
20) -18.8498 Variable 1.000000
* 21) -30.1253 1.3000 1.689480 31.02
22) 40.4709 1.9883 1.000000
* 23) 37.2836 3.3332 1.808350 40.55
24) ∞ 19.7825 1.000000
25) ∞ 1.6000 1.516800 64.13
26) ∞ 1.0059 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
4 0.0000 9.77757E-06 -1.86856E-10 3.61428E-11 -7.97773E-14 0.95711E-16
17 0.0000 -3.98939E-05 -3.97571E-08 -4.94760E-10 2.83561E-12 -0.20949E-13
21 2.6936 1.03810E-04 -7.47656E-07 5.22059E-09 -2.32930E-11 0.46411E-13
23 1.0000 -6.38484E-05 4.30545E-07 -2.33889E-09 8.08344E-12 -0.12063E-13
[Various data]
f 27.0000
Fno 1.8511
2ω 80.1035
Ymax 21.60
TL 115.00586
Air conversion TL 114.46066
Bf 22.38833
Air conversion Bf 21.84313
Ainf 40.75144
Amod 39.9517
Point at infinity short distance f 27.0000
β -0.1432
d0 ∞ 168.6086
d11 5.9402 2.4572
d15 4.0055 7.4884
d16 8.4916 6.7346
d20 3.8298 5.5867
2ω 80.1035
ω 40.0518
[Lens group data]
Group starting surface f
GF 1 50.0572
GR 17 68.9718
GFA 1 67.4727
GFF 12 375.4378
GRF 17 32.8785
GRB 21 -60.8771
[Conditional expression correspondence value]
(1) XRF / XFF = 0.5044
(2) Bf / f = 0.8090
(3) ST / TL = 0.4502
(4) βRF / βFF = 0.4980
(5) (-fRB) /f=2.2547
(6) Bf / TL = 0.1908
(7) XRF / f = 0.0651
(8) fRF / fFF = 0.0876
(9) fF / fR = 0.7258
(10) fFA / fFF = 0.1797
(11) f / fFF = 0.0719
(12) f / fRF = 0.8212
(13) TL / (Fno ・ Bf) = 2.8308
(14) | Ainf-Amod | / f = 0.0296
(15) νFFp-νFFn = 57.3000
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.2782
(17) nRBp-nRBn = 0.1189
(18) nRBp + 0.005νRBp = 2.0111
(19) nRBn + 0.005νRBn = 1.8446

10 (a) and 10 (b) are aberration diagrams of the optical system according to the fifth embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(6th Example)
11 (a) and 11 (b) are cross-sectional views of the optical system according to the sixth embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the sixth embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA consists of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the image side, a biconcave negative lens L3, and a biconvex positive lens in order from the object side. It is composed of a bonded lens with a lens L4 and a bonded lens with a biconvex positive lens L5 and a biconcave negative lens L6.
The front focusing group GFF is composed of a junction lens of a plano-convex positive lens L7 having a convex surface facing the object side and a plano-concave negative lens L8 having a concave surface facing the image side in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a negative meniscus lens L9 having a convex surface facing the image side and a biconvex positive lens L10 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L11 and a biconvex positive lens L12 in order from the object side.

In the optical system according to the sixth embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved toward the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.
Table 6 below lists the values of the specifications of the optical system according to the sixth embodiment.

(Table 6) Sixth Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 348.4574 2.4000 1.504120 59.90
* 2) 21.4609 13.4044 1.000000
3) -105.0871 4.5427 1.922860 20.88
4) -64.8044 3.8789 1.000000
5) -34.8938 2.0000 1.632947 34.71
6) 40.3703 11.1155 1.834810 42.73
7) -48.0907 0.2187 1.000000
8) 31.3856 7.6538 1.834810 42.73
9) -144.1208 1.6000 1.657414 32.27
10) 31.7227 Variable 1.000000
11) 28.8127 5.3410 1.497820 82.57
12) ∞ 1.2002 1.713322 30.66
13) 55.4010 Variable 1.000000
14) (Aperture S) ∞ Variable 1.000000
* 15) -46.5696 1.8000 1.728267 45.36
16) -592.3084 0.2365 1.000000
17) 51.5274 10.3228 1.497820 82.57
* 18) -18.0668 Variable 1.000000
19) -48.0041 1.4000 1.593929 38.23
20) 55.8143 2.2498 1.000000
* 21) 102.4799 3.8639 1.906998 28.77
22) -1000.0000 17.2535 1.000000
23) ∞ 1.6000 1.516800 64.13
24) ∞ 0.9835 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
2 0.0000 1.12877E-05 7.54278E-09 3.77786E-11 -8.64032E-14 0.22683E-15
15 0.0000 -3.85799E-05 -9.55276E-08 2.02210E-10 -5.21627E-12 0.22387E-13
18 1.0000 1.16752E-05 -2.00823E-08 2.86154E-10 -7.78259E-13 0.34805E-14
21 1.0000 3.63716E-06 -5.43228E-09 2.25434E-11 -7.54064E-14 0.77846E-16
[Various data]
f 34.0000
Fno 1.84694
2ω 68.7634
Ymax 21.60
TL 114.98352
Air conversion TL 114.43832
Bf 19.83701
Air conversion Bf 19.29181
Ainf 34.37218
Amod 33.44787
Point at infinity short distance f 34.0000
β -0.1434
d0 ∞ 216.6806
d10 5.4302 2.1248
d13 4.0990 7.4045
d14 9.0459 6.1458
d18 3.3432 6.2432
2ω 68.7634
ω 34.3817
[Lens group data]
Group starting surface f
GF 1 47.9103
GR 15 86.8580
GFA 1 78.4519
GFF 11 186.8714
GRF 15 40.9478
GRB 19 -78.5376
[Conditional expression correspondence value]
(1) XRF / XFF = 0.8773
(2) Bf / f = 0.5674
(3) ST / TL = 0.4505
(4) βRF / βFF = 0.8696
(5) (-fRB) /f=2.3099
(6) Bf / TL = 0.1686
(7) XRF / f = 0.0853
(8) fRF / fFF = 0.2191
(9) fF / fR = 0.5516
(10) fFA / fFF = 0.4198
(11) f / fFF = 0.1819
(12) f / fRF = 0.8303
(13) TL / (Fno ・ Bf) = 3.2118
(14) | Ainf-Amod | / f = 0.0272
(15) νFFp-νFFn = 51.9700
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 1.000
(17) nRBp-nRBn = 0.3130
(18) nRBp + 0.005νRBp = 2.0508
(19) nRBn + 0.005νRBn = 1.7851

12 (a) and 12 (b) are aberration diagrams of the optical system according to the sixth embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(7th Example)
13 (a) and 13 (b) are cross-sectional views of the optical system according to the seventh embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the seventh embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA consists of a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the image side, a biconvex positive lens L3, and a biconcave lens in order from the object side. It is composed of a junction lens of a negative lens L4 and a biconvex positive lens L5, and a biconvex positive lens L6. The negative meniscus lens L2 is a composite aspherical lens formed by arranging a resin on the image side lens surface to form an aspherical shape.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a negative meniscus lens L9 having a convex surface facing the image side and a biconvex positive lens L10 in order from the object side.
The negative lens group GRB is composed of a positive meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a plano-convex positive lens L13 having a convex surface facing the object side in order from the object side. ..

In the optical system according to the seventh embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved toward the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.
Table 7 below lists the values of the specifications of the optical system according to the seventh embodiment.

(Table 7) Seventh Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 97.4192 2.2000 1.768494 44.86
2) 25.3748 9.4393 1.000000
3) 73.0366 1.6500 1.611353 59.10
4) 28.1065 0.1500 1.513800 52.97
* 5) 23.3508 8.7999 1.000000
6) 314.3211 3.3152 1.922860 20.88
7) -230.9882 3.9581 1.000000
8) -54.6239 2.1432 1.620040 36.40
9) 34.0933 10.7170 1.834810 42.73
10) -93.8515 0.2008 1.000000
11) 45.4462 5.5158 1.834810 42.73
12) -76941.34500 Variable 1.000000
13) 40.4893 4.1495 1.497820 82.57
14) -135.4706 1.2000 1.808090 22.74
15) 126.4048 Variable 1.000000
16) (Aperture S) ∞ Variable 1.000000
* 17) -20.6195 1.7865 1.860999 37.10
* 18) -32.1327 1.4206 1.000000
19) 102.6671 7.8877 1.497820 82.57
20) -16.3909 Variable 1.000000
21) 57.0592 2.6167 1.710936 47.27
22) 304.2075 4.1090 1.000000
* 23) -22.4255 1.3000 1.689480 31.02
24) 61.5136 2.0782 1.000000
* 25) 36.1918 2.6262 1.820980 42.50
26) ∞ 12.6819 1.000000
27) ∞ 1.6000 1.516800 63.88
28) ∞ 1.0000 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
5 0.0000 4.47584E-07 -6.22190E-09 1.22365E-11 -3.40101E-14 0.32669E-16
17 0.0000 9.62834E-05 -4.19153E-07 -3.28271E-09 2.90182E-11 -0.13502E-12
18 1.0000 1.33216E-04 -1.90915E-07 -3.36920E-09 2.71394E-11 -0.83703E-13
23 1.9124 1.43602E-04 -8.35674E-07 5.32507E-09 -1.97434E-11 0.34513E-13
25 1.0000 -8.47161E-05 4.39056E-07 -2.13972E-09 6.18894E-12 -0.71916E-14
[Various data]
f 20.4000
Fno 1.85009
2ω 96.1353
Ymax 21.60
TL 115.02541
Air conversion TL 114.48021
Bf 15.28192
Air conversion Bf 14.73672
Ainf 48.76762
Amod 48.15648
Point at infinity short distance f 20.4000
β -0.1972
d0 ∞ 84.0279
d12 6.0921 2.2355
d15 4.3398 8.1964
d16 9.0834 5.6834
d20 2.9645 6.3646
2ω 96.1353
ω 48.0677
[Lens group data]
Group starting surface f
GF 1 40.2194
GR 17 51.7452
GFA 1 59.7587
GFF 13 253.1359
GRF 17 40.2592
GRB 21 -156.7545
[Conditional expression correspondence value]
(1) XRF / XFF = 0.8816
(2) Bf / f = 0.7224
(3) ST / TL = 0.4421
(4) βRF / βFF = 0.6742
(5) (-fRB) /f=7.684
(6) Bf / TL = 0.1287
(7) XRF / f = 0.1667
(8) fRF / fFF = 0.1590
(9) fF / fR = 0.7773
(10) fFA / fFF = 0.2361
(11) f / fFF = 0.0806
(12) f / fRF = 0.5067
(13) TL / (Fno ・ Bf) = 4.1989
(14) | Ainf-Amod | / f = 0.0300
(15) νFFp-νFFn = 59.8300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.5398
(17) nRBp-nRBn = 0.0765
(18) nRBp + 0.005νRBp = 1.9904
(19) nRBn + 0.005νRBn = 1.8446

14 (a) and 14 (b) are aberration diagrams of the optical system according to the seventh embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(8th Example)
15 (a) and 15 (b) are cross-sectional views of the optical system according to the eighth embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the eighth embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA includes a biconcave negative lens L1, a junction lens of a biconcave negative lens L2 and a biconvex positive lens L3, and a biconvex positive lens L4 in order from the object side. It consists of a junction lens with a concave negative lens L5.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L6 and a biconcave negative lens L7 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a biconcave negative lens L8 and a biconvex positive lens L9 in order from the object side.
The negative lens group GRB is composed of a negative meniscus lens L10 having a convex surface facing the image side and a negative meniscus lens L11 having a convex surface facing the image side in order from the object side.

In the optical system according to the eighth embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved to the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.
Table 8 below lists the values of the specifications of the optical system according to the eighth embodiment.

(Table 8) Example 8
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) -1384.5606 2.4000 1.518230 58.82
* 2) 22.7521 19.5726 1.000000
3) -210.4727 2.0000 1.603420 38.03
4) 34.8221 11.0013 1.834810 42.73
5) -98.9663 0.2000 1.000000
6) 41.5127 8.8597 1.834810 42.73
7) -70.1358 1.6000 1.647690 33.72
8) 41.7744 Variable 1.000000
9) 30.8554 5.2069 1.497820 82.57
10) -344.9897 1.2000 1.672700 32.18
11) 59.4370 Variable 1.000000
12) (Aperture S) ∞ Variable 1.000000
* 13) -128.3993 1.8000 1.834810 42.73
14) 316.2495 1.3930 1.000000
15) 98.6994 10.2289 1.497820 82.57
* 16) -18.9378 Variable 1.000000
17) -47.2364 3.0654 1.902650 35.72
18) -35.8672 5.9831 1.000000
19) -30.0877 1.4000 1.688931 31.07
20) -1077.5863 14.3679 1.000000
21) ∞ 1.6000 1.516800 64.13
22) ∞ 0.9778 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
2 0.0000 8.60806E-06 -2.33850E-09 3.59347E-11 -7.01381E-14 0.61254E-16
13 0.0000 -3.09776E-05 -8.13151E-08 -2.38297E-10 2.73111E-14 -0.12604E-13
16 1.0000 4.53043E-07 -2.70015E-08 4.55831E-11 -6.17207E-13 0.12765E-14
[Various data]
f 34.1413
Fno 1.85683
2ω 65.0328
Ymax 21.60
TL 114.97777
Air conversion TL 114.43257
Bf 53.1934
Air conversion Bf 54.6482
Ainf 33.09508
Amod 32.1484
Point at infinity short distance f 34.1413
β -0.1418
d0 ∞ 221.3238
d8 5.7439 2.0995
d11 4.0000 7.6445
d12 9.1921 6.0059
d16 3.1853 6.3715
2ω 65.0328
ω 32.5164
[Lens group data]
Group starting surface f
GF 1 57.9019
GR 13 86.1509
GFA 1 102.0669
GFF 9 196.0962
GRF 13 42.5650
GRB 17 -65.8197
[Conditional expression correspondence value]
(1) XRF / XFF = 0.8743
(2) Bf / f = 1.5421
(3) ST / TL = 0.1433
(4) βRF / βFF = 0.8301
(5) (-fRB) /f=1.9279
(6) Bf / TL = 0.4600
(7) XRF / f = 0.0933
(8) fRF / fFF = 0.2171
(9) fF / fR = 0.6721
(10) fFA / fFF = 0.5205
(11) f / fFF = 0.1741
(12) f / fRF = 0.8021
(13) TL / (Fno ・ Bf) = 1.1706
(14) | Ainf-Amod | / f = 0.0277
(15) νFFp-νFFn = 50.3900
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.8358
(17) nRBp-nRBn = 0.2137
(18) nRBp + 0.005νRBp = 2.0813
(19) nRBn + 0.005νRBn = 1.8443

16 (a) and 16 (b) are aberration diagrams of the optical system according to the eighth embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(9th Example)
17 (a) and 17 (b) are cross-sectional views of the optical system according to the ninth embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the ninth embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA consists of a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, a biconcave negative lens L3, and a convex surface toward the object side, in order from the object side. It is composed of a junction lens of a negative meniscus lens L4 facing the lens and a biconvex positive lens L5, and a positive meniscus lens L6 having a convex surface facing the object side.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a negative meniscus lens L9 having a convex surface facing the image side and a biconvex positive lens L10 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L11 and a biconvex positive lens L12 in order from the object side.

In the optical system according to the ninth embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved toward the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.
Table 9 below lists the values of the specifications of the optical system according to the ninth embodiment.

(Table 9) Example 9
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 90.1539 2.0000 1.658440 50.83
2) 35.0000 1.0023 1.000000
3) 38.0000 1.8000 1.622910 58.30
* 4) 17.5155 13.7363 1.000000
5) -135.7140 1.6000 1.593190 67.90
6) 48.9808 6.5355 1.000000
7) 861.6049 2.4809 1.620040 36.40
8) 31.3689 9.0000 1.851500 40.78
9) -150.1624 3.1783 1.000000
10) 40.3712 5.2632 1.851500 40.78
11) 1025.5030 Variable 1.000000
12) 32.7343 4.0000 1.497820 82.57
13) -155.0414 1.2000 1.808090 22.74
14) 62.0187 Variable 1.000000
15) (Aperture S) ∞ Variable 1.000000
* 16) -45.5353 2.0000 1.860999 37.10
* 17) -52.3373 1.5881 1.000000
18) 60.0000 7.3310 1.497820 82.57
19) -19.2015 Variable 1.000000
* 20) -27.0655 1.2000 1.689480 31.02
21) 81.9849 1.4246 1.000000
* 22) 43.0859 4.0000 1.882023 37.22
23) -1000.0000 17.7393 1.000000
24) ∞ 1.6000 1.516800 63.88
25) ∞ 1.0000 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
4 0.0000 1.52130E-05 -1.37943E-09 1.13792E-10 -3.10899E-13 0.49329E-15
16 0.0000 -3.46585E-05 1.35812E-08 1.68641E-09 -1.95052E-11 0.59812E-13
17 1.0000 2.60772E-06 8.97314E-08 1.41490E-09 -1.26537E-11 0.35190E-13
20 1.5918 1.23579E-04 -8.07461E-07 5.37616E-09 -2.11181E-11 0.34821E-13
22 1.0000 -8.27671E-05 4.88811E-07 -2.91586E-09 9.85401E-12 -0.14168E-13
[Various data]
f 20.0000
Fno 1.854
2ω 97.6294
Ymax 21.60
TL 114.09
Air conversion TL 113.5448
Bf 20.33935
Air conversion Bf 19.79415
Ainf 48.68147
Amod 47.75113
Point at infinity short distance f 20.0000
β -0.1987
d0 ∞ 80.5848
d11 8.0031 5.1763
d14 5.0918 7.9186
d15 7.1424 4.7424
d19 4.1730 6.5730
2ω 97.6294
ω 48.8147
[Lens group data]
Group starting surface f
GF 1 51.8791
GR 16 47.3528
GFA 1 59.9544
GFF 12 1108.3235
GRF 16 31.1504
GRB 20 -88.9793
[Conditional expression correspondence value]
(1) XRF / XFF = 0.8490
(2) Bf / f = 0.9897
(3) ST / TL = 0.4285
(4) βRF / βFF = 0.3388
(5) (-fRB) /f=4.4490
(6) Bf / TL = 0.1743
(7) XRF / f = 0.1200
(8) fRF / fFF = 0.0281
(9) fF / fR = 1.0956
(10) fFA / fFF = 0.0541
(11) f / fFF = 0.0180
(12) f / fRF = 0.6420
(13) TL / (Fno ・ Bf) = 3.0940
(14) | Ainf-Amod | / f = 0.0465
(15) νFFp-νFFn = 59.8300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.6513
(17) nRBp-nRBn = 0.1925
(18) nRBp + 0.005νRBp = 1.6719
(19) nRBn + 0.005νRBn = 2.0681

18 (a) and 18 (b) are aberration diagrams of the optical system according to the ninth embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.

From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(10th Example)
19 (a) and 19 (b) are cross-sectional views of the optical system according to the tenth embodiment when focusing on an infinite object and when focusing on a short-range object, respectively.
The optical system according to the ninth embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the image side. It is composed of a junction lens of a biconcave negative lens L4 and a biconvex positive lens L5, and a biconvex positive lens L6.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L7 and a biconcave negative lens L8 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a negative meniscus lens L9 having a convex surface facing the image side and a biconvex positive lens L10 in order from the object side.
The negative lens group GRB is composed of a biconcave negative lens L11.

In the optical system according to the tenth embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved toward the object side along the optical axis to focus from an infinity object to a short-range object. At the time of focusing, the positions of the positive lens group GFA, the aperture stop S and the negative lens group GRB are fixed.
Table 10 below lists the values of the specifications of the optical system according to the tenth embodiment.

(Table 10) Example 10
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 105.7357 2.3000 1.785897 43.93
2) 30.3881 7.3810 1.000000
3) 55.0000 2.0000 1.658441 50.88
* 4) 18.9645 13.6074 1.000000
5) -171.0476 4.6738 1.785896 44.20
6) -49.1804 3.4817 1.000000
7) -43.6767 1.7001 1.603420 38.01
8) 37.4040 8.0414 1.851500 40.78
9) -251.6551 4.7235 1.000000
10) 37.7511 6.3961 1.851500 40.78
11) -472.8256 Variable 1.000000
12) (Virtual surface) ∞ 0.0000 1.000000
13) 56.1535 4.8469 1.497820 82.57
14) -61.5295 1.7129 1.808090 22.74
15) 251.7243 Variable 1.000000
16) (Aperture S) ∞ Variable 1.000000
* 17) -60.5230 1.2000 1.860999 37.10
* 18) -100.0047 1.3930 1.000000
19) 59.4711 7.5979 1.497820 82.57
20) -16.5046 Variable 1.000000
* 21) -554.5946 1.3092 1.740769 27.79
* 22) 32.1694 17.9272 1.000000
23) ∞ 1.6000 1.516800 64.13
24) ∞ 0.9825 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
4 0.0000 9.44198E-06 -7.85173E-10 1.82058E-11 -5.42737E-14 0.53658E-16
17 1.0000 -3.05779E-05 -1.19989E-07 -2.26470E-09 4.74211E-12 -0.32614E-15
18 1.0000 1.85793E-05 6.97129E-09 -1.71822E-09 6.73792E-12 0.27686E-13
21 1.0000 -2.35430E-05 -5.88083E-08 1.25271E-09 -1.14966E-11 0.26434E-13
22 1.0000 -1.41315E-05 -1.06653E-07 1.37968E-09 -9.70244E-12 0.22570E-13
[Various data]
f 20.6000
Fno 1.85674
2ω 95.6062
Ymax 21.60
TL 114.98248
Air conversion TL 114.43728
Bf 20.50968
Air conversion Bf 19.96448
Ainf 48.46075
Amod 48.04852
Point at infinity short distance f 20.6000
β -0.1881
d0 ∞ 87.1901
d11 5.6564 2.5472
d15 4.2430 7.3520
d16 8.5222 6.5750
d20 3.6864 5.6336
2ω 95.6062
ω 47.8031
[Lens group data]
Group starting surface f
GF 1 33.8040
GR 17 81.1675
GFA 1 37.0214
GFF 12 1160.9972
GRF 17 30.1283
GRB 21 -41.0072
[Conditional expression correspondence value]
(1) XRF / XFF = 0.6263
(2) Bf / f = 0.9691
(3) ST / TL = 0.3816
(4) βRF / βFF = 0.4486
(5) (-fRB) /f=1.9906
(6) Bf / TL = 0.1745
(7) XRF / f = 0.0945
(8) fRF / fFF = 0.0260
(9) fF / fR = 0.4165
(10) fFA / fFF = 0.0319
(11) f / fFF = 0.0177
(12) f / fRF = 0.6837
(13) TL / (Fno ・ Bf) = 3.0872
(14) | Ainf-Amod | / f = 0.0200
(15) νFFp-νFFn = 59.8300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.0457
(19) nRBn + 0.005νRBn = 1.8797

20 (a) and 20 (b) are aberration diagrams of the optical system according to the tenth embodiment when focusing on an infinite object and when focusing on a short-distance object, respectively.
From each aberration diagram, it can be seen that the optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object, and has excellent imaging performance.

(11th Example)
21 (a) and 21 (b) are cross-sectional views of the variable magnification optical system according to the eleventh embodiment when the infinity object is in focus in the wide-angle end state and the telephoto end state, respectively.
The variable magnification optical system according to the eleventh embodiment is composed of a front group GF having a positive refractive power, an aperture stop S, and a rear group GR having a positive refractive power in order from the object side. A filter F is arranged near the object side of the image plane I.

The front group GF is composed of a positive lens group GFA having a positive refractive power and a front focusing group GFF having a positive refractive power in order from the object side.
The positive lens group GFA is composed of a negative lens group GFA1 having a negative refractive power and a positive lens group GFA2 having a positive refractive power in order from the object side.
The negative lens group GFA1 consists of a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side, in order from the object side. Become.
The positive lens group GFA2 is composed of a junction lens of a negative meniscus lens L4 having a convex surface facing the object side and a biconvex positive lens L5 in order from the object side.
The front focusing group GFF is composed of a junction lens of a biconvex positive lens L6 and a biconcave negative lens L7 in order from the object side.

The rear group GR is composed of a rear focusing group GRF having a positive refractive power and a negative lens group GRB having a negative refractive power in order from the object side.
The rear focusing group GRF is composed of a biconvex positive lens L8, a negative meniscus lens L9 having a convex surface facing the object side, and a junction lens of a biconvex positive lens L10 in order from the object side.
The negative lens group GRB includes a biconcave negative lens L11 and a plano-convex positive lens L12 with a convex surface facing the object side.

In the variable magnification optical system according to the eleventh embodiment, the distance between the negative lens group GFA1 and the positive lens group GFA2 decreases when the magnification is changed from the wide-angle end state to the telescopic end state, and the rear focusing group GRF and the negative lens group The negative lens group GFA1 moves toward the image side along the optical axis so that the GRB spacing increases, and the positive lens group GFA2, the front focusing group GFF, the aperture aperture S, and the rear focusing group GRF move to the optical axis. It moves integrally to the object side along the optical axis, and the negative lens group GRB moves to the object side along the optical axis.

In the variable magnification optical system according to the eleventh embodiment, the anterior focusing group GFF and the posterior focusing group GRF are moved to the object side along the optical axis to focus from an infinity object to a short-range object. .. At the time of focusing, the positions of the negative lens group GFA1, the positive lens group GFA2, the aperture stop S, and the negative lens group GRB are fixed.
Table 11 below lists the values of the specifications of the variable magnification optical system according to the eleventh embodiment. In Table 10, W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

(Table 11) 11th Example
[Surface data]
Surface number r d nd ν d
Paraboloid ∞ 1.000000
1) 109.0633 2.7000 1.638540 55.34
* 2) 18.2077 12.4865 1.000000
3) 495.8681 2.0000 1.832199 40.10
* 4) 44.2568 9.5236 1.000000
5) 52.5025 4.8000 1.903658 31.31
6) 159.6343 Variable 1.000000
7) 57.0442 1.3000 1.903658 31.31
8) 30.3255 4.5545 1.834000 37.18
9) -195.4912 Variable 1.000000
10) 34.2035 4.3182 1.487490 70.32
11) -47.4756 2.2701 1.784696 26.29
12) 111.8345 Variable 1.000000
13) (Aperture S) ∞ 3.0000 1.000000
14) (Virtual surface) ∞ Variable 1.000000
* 15) 47.8005 3.0298 1.801000 34.92
* 16) -89.2527 1.3930 1.000000
17) 147.9048 1.2000 1.717000 47.97
18) 18.1175 5.5049 1.497820 82.57
19) -21.4691 Variable 1.000000
* 20) -28.3302 1.3000 1.800999 34.97
21) 40.6201 1.9545 1.000000
* 22) 42.1307 3.1144 1.516800 64.13
23) ∞ 19.0966 1.000000
24) ∞ 1.6000 1.516800 64.13
25) ∞ Variable 1.000000
Image plane ∞
[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
2 0.0000 8.83674E-06 1.69121E-08 -7.80852E-13 -2.62893E-14 0.29153E-15
4 0.0000 4.63846E-06 -4.54541E-09 8.68492E-12 -6.95178E-14 0.99796E-16
15 0.0000 -1.84011E-05 -1.16137E-07 2.01508E-10 -2.76953E-11 -0.12398E-12
16 1.0000 2.48230E-06 -1.38570E-08 -4.12767E-09 5.44261E-11 -0.60620E-12
20 0.0000 6.56671E-05 -4.14077E-07 7.30290E-11 2.75237E-11 -0.16734E-12
22 1.0000 -9.56724E-05 5.39674E-07 -2.04380E-09 1.77405E-14 0.25533E-13
[Various data]
Scale ratio 1.31707
WMT
f 20.5000 23.87447 27.0000
Fno 3.98168 4.21631 4.45032
2ω 99.4639 78.1570
Ymax 22.10 22.10 22.10
TL 124.40748 117.05375 112.89064
Air conversion TL 123.86228 116.50855 112.34544
Bf 21.65029 23.31104 25.1404
Air conversion Bf 21.10509 22.76584 24.5952
Ainf 49.6919 43.47611 39.14618
Amod 49.31936 43.09172 38.74231
WWTT
Point at infinity Short distance Point at infinity Short distance f 20.5000 27.0000
β -0.0971 -0.0976
d0 ∞ 190.2532 ∞ 259.2733
d6 19.4177 19.4177 3.0621 3.0622
d9 5.8637 4.8842 5.8637 4.6753
d12 4.0208 5.0002 4.0208 5.2088
d14 5.4611 4.9170 5.4611 4.8304
d19 3.5448 4.0891 4.8933 5.5240
d25 0.9537 0.9537 4.4438 4.4438
2ω 99.4639 78.1570
ω 49.7319 39.0785
[Lens group data]
WT
Group starting surface f f
GF 1 53.8809 118.2665
GR 15 75.7150 66.6110
GFA1 1 -32.1287
GFA2 7 56.6718
GFA 1 71.4662 199.6032
GFF 10 625.4485
GRF 15 25.9374
GRB 20 -28.8034
[Conditional expression correspondence value]
(1) XRF / XFF = 0.5556
(2) Bf / f = 1.0295
(3) ST / TL = 0.4086
(4) βRF / βFF = 0.2630
(5) (-fRB) /f=1.4050
(6) Bf / TL = 0.1704
(7) XRF / f = 0.0266
(8) fRF / fFF = 11.0363
(9) fF / fR = 0.7116
(10) fFA / fFF = 0.1143 (wide-angle end), 0.3191 (telephoto end)
(11) f / fFF = 0.0328
(12) f / fRF = 0.7904
(13) TL / (Fno ・ Bf) = 1.4740
(14) | Ainf-Amod | / f = 0.0182
(15) νFFp-νFFn = 44.0300
(16) (FFr2 + FFr1) / (FFr2-FFr1) = 0.1625
(17) nRBp-nRBn = -0.2842
(18) nRBp + 0.005νRBp = 1.8375
(19) nRBn + 0.005νRBn = 1.9758

22 (a) and 22 (b) are aberration diagrams at the time of focusing on an infinity object and the time of focusing on a short-distance object in the wide-angle end state of the variable magnification optical system according to the eleventh embodiment, respectively.
23 (a) and 23 (b) are aberration diagrams at the time of focusing on an infinity object and the time of focusing on a short-distance object in the telephoto end state of the variable magnification optical system according to the eleventh embodiment, respectively.
From each aberration diagram, the variable magnification optical system according to this embodiment satisfactorily corrects various aberrations from the time of focusing on an infinite object to the time of focusing on a short-range object in each focal length state, and has excellent imaging performance. You can see that.

According to each of the above embodiments, it is suitable for a mirrorless camera, and it is possible to realize an optical system having good optical performance by suppressing fluctuations in various aberrations during focusing while reducing the weight of the focusing group. ..

It should be noted that each of the above examples shows a specific example of the invention of the present application, and the invention of the present application is not limited thereto. The following contents can be appropriately adopted as long as the optical performance of the optical system of the present embodiment is not impaired.

As an example of the optical system of the present embodiment, a two-group configuration is shown, but the present application is not limited to this, and an optical system having another group configuration (for example, three groups or the like) can also be configured. Specifically, a lens or a lens group may be added to the most object side, the most image side, or the like of the optical system of each of the above embodiments. Further, the front group and the rear group are shown to have a two-group or three-group configuration, but the present application is not limited to this, and other group configurations (for example, four groups, etc.) may be used. Specifically, it is negative between the most object side and the most image side of the front group, between the positive lens group and the front focusing group, and the most object side, the most image side, and the posterior focusing group of the rear group in each of the above embodiments. A lens or a lens group may be added between the lens groups.

In the optical system of each of the above examples, the anterior focusing group and the posterior focusing group are the focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by a motor for autofocus, for example, an ultrasonic motor, a stepping motor, a VCM motor, etc., and has high-speed autofocus and auto. Quietness at the time of focusing can be satisfactorily achieved.

Further, in the optical system of each of the above embodiments, the entire lens group or a part thereof is moved as an anti-vibration lens group so as to include a component in the direction perpendicular to the optical axis, or in-plane including the optical axis. It is also possible to provide vibration isolation by rotating (swinging) in the direction.
Further, the aperture diaphragm in the optical system of each of the above embodiments may be configured such that a lens frame substitutes the role of the aperture diaphragm without providing a member as the aperture diaphragm.

Further, the lens surface of the lens constituting the optical system of each of the above embodiments may be a spherical surface or a flat surface, or may be an aspherical surface. Further, each lens may be formed of a glass material, a resin material, or a composite of a glass material and a resin material. When the lens surface is spherical or flat, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented, which is preferable. Further, even if the image plane is displaced, the deterioration of the depiction performance is small, which is preferable. When the lens surface is aspherical, it can be either an aspherical surface formed by grinding, a glass mold aspherical surface formed by molding glass into an aspherical shape, or a composite aspherical surface formed by forming a resin provided on the glass surface into an aspherical shape. good. Further, the lens surface may be a diffraction surface, and the lens may be a refractive index distribution type lens (GRIN lens) or a plastic lens.

Further, an antireflection film may be applied to the lens surface of the lens constituting the optical system of each of the above embodiments. As a result, flares and ghosts can be reduced, and high-contrast and high optical performance can be achieved. In particular, in the optical system of each of the above embodiments, it is preferable to provide an antireflection film on the lens surface of the second lens on the object side, counting from the object side.

Next, a camera provided with the optical system of the present embodiment will be described with reference to FIG. 24.
FIG. 24 is a diagram showing a configuration of a camera provided with the optical system of the present embodiment.
As shown in FIG. 24, the camera 1 is a lens-interchangeable mirrorless camera provided with the optical system according to the first embodiment as the photographing lens 2.

In the present camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and passed through an OLPF (Optical low pass filter) (not shown) on the image pickup surface of the image pickup unit 3. Form a subject image. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the image pickup unit 3, and the image of the subject is generated. This image is displayed on an EVF (Electronic viewfinder) 4 provided in the camera 1. This allows the photographer to observe the subject via the EVF4.
Further, when the photographer presses the release button (not shown), the image of the subject generated by the image pickup unit 3 is stored in the memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

This camera 1 is suitable for a mirrorless camera because it is equipped with the optical system according to the first embodiment as the photographing lens 2, and changes in various aberrations during focusing while reducing the weight of the focusing group. It is possible to suppress and realize good optical performance.

Even if a camera having the optical system according to the second to eleventh embodiments mounted as the photographing lens 2 is configured, the same effect as that of the camera 1 can be obtained. Further, even when the single-lens reflex type camera having a quick return mirror and observing the subject by the finder optical system is equipped with the optical system according to each of the above embodiments, the same effect as that of the camera 1 can be obtained.

Finally, an outline of the method for manufacturing the optical system of the present embodiment will be described with reference to FIG. 25.
FIG. 25 is a diagram showing an outline of a method for manufacturing an optical system according to the present embodiment.
The method for manufacturing the optical system of the present embodiment shown in FIG. 25 is a method for manufacturing an optical system including a front group having a positive refractive power, an aperture stop, and a rear group in order from the object side, and is as follows. It includes steps S1 to S5.

Step S1: The front group, the aperture stop and the rear group are prepared and arranged in the lens barrel in order from the object side.
Step S2: Make the front group have a front focusing group having a positive refractive power.
Step S3: Make the posterior group have a posterior focusing group having a positive refractive power.
Step S4: At the time of focusing, the front focusing group and the focusing group move to the object side.

Step S5: The anterior focusing group and the posterior focusing group satisfy the following conditional expression (1).
(1) 0.250 <XRF / XFF <1.500
However,
XFF: Movement amount of the front focusing group when focusing from an infinity object to a short-distance object XRF: Movement amount of the rear focusing group when focusing from an infinity object to a short-distance object

According to the method for manufacturing an optical system according to the present embodiment, the optical system is suitable for a mirrorless camera, and has good optical performance by suppressing fluctuations in various aberrations during focusing while reducing the weight of the focusing group. The system can be manufactured.

GFA: Positive lens group, GFF: Anterior focus group, GRF: Posterior focus group, GRB: Negative lens group, S: Aperture aperture, I: Image plane

Claims (33)

From the object side, it consists of a front group with a positive refractive power, an aperture stop, and a rear group.
The front group includes, in order from the object side, a positive lens group having positive refractive power, and a front case Asegun having positive refractive power,
The posterior group has a posterior focusing group having a positive refractive power.
At the time of focusing, the front focusing group and the rear focusing group move to the object side, the position of the aperture stop is fixed, and the distance between the positive lens group and the front focusing group changes.
An optical system that satisfies the following conditional expression.
0.250 <XRF / XFF <1.500
0.010 <fFA / fFF <0.750
However,
XFF: Movement amount of the front focusing group when focusing from an infinity object to a short-distance object XRF: Movement amount of the rear focusing group when focusing from an infinity object to a short-distance object
fFA: Focal length of the positive lens group
fFF: Focal length of the front focusing group The optical system according to claim 1, which satisfies the following conditional expression.
0.400 <Bf / f <2.000
However,
Bf: Distance from the image side lens surface of the lens located closest to the image side when the infinity object is in focus f: Focal length of the optical system when the infinity object is in focus The optical system according to claim 1 or 2 , which satisfies the following conditional expression.
0.100 <ST / TL <0.600
However,
ST: Distance from the aperture stop to the image plane when the object is in focus at infinity TL: Distance from the lens surface on the object side of the lens located on the closest object side to the image plane when the object is in focus at infinity. The optical system according to any one of claims 1 to 3 , which satisfies the following conditional expression.
0.200 <βRF / βFF <1.10
However,
βFF: Magnification of the anterior focusing group βRF: Magnification of the posterior focusing group The optical system according to any one of claims 1 to 4 , wherein the position of the positive lens group is fixed at the time of focusing. The optical system according to any one of claims 1 to 5 position of the lens positioned closest to the image side when focusing is fixed. The optical system according to any one of claims 1 to 6 , wherein the front focusing group has at least one positive lens and at least one negative lens. The optical system according to any one of claims 1 to 7 , wherein the rear focusing group has at least one positive lens and at least one negative lens. The rear group includes, in order from the object side, and the rear focusing lens group, have a negative lens group having a negative refractive power, the distance between the negative lens group and the rear focusing lens group when focusing The optical system according to any one of claims 1 to 8, which changes. The optical system according to claim 9 , which satisfies the following conditional expression.
0.800 <(-fRB) /f<10.000
However,
fRB: Focal length of the negative lens group f: Focal length of the optical system when focusing on an object at infinity The optical system according to any one of claims 1 to 10 , which satisfies the following conditional expression.
0.060 <Bf / TL <0.650
However,
Bf: Distance from the image side lens surface of the lens located closest to the image side when the infinity object is in focus TL: From the object side lens surface of the lens located closest to the object side when the infinity object is in focus Distance to the image plane The optical system according to any one of claims 1 to 11 , which satisfies the following conditional expression.
0.010 <XRF / f <0.240
However,
XRF: Movement amount of the rear focusing group when focusing from an infinite object to a short-distance object f: Focal length of the optical system when focusing on an infinite object The optical system according to any one of claims 1 to 12 , wherein the lens located closest to the object has a negative refractive power. The optical system according to any one of claims 1 to 13 , wherein the rear group has a positive refractive power. The optical system according to any one of claims 1 to 14 , which satisfies the following conditional expression.
0.010 <fRF / fFF <0.990
However,
fFF: Focal length of the anterior focusing group fRF: Focal length of the posterior focusing group The optical system according to any one of claims 1 to 15 , which satisfies the following conditional expression.
0.300 <fF / fR <1.300
However,
fF: Focal length of the front group when focusing on an infinity object fR: Focal length of the rear group when focusing on an infinity object The optical system according to any one of claims 1 to 16 , which satisfies the following conditional expression.
0.010 <f / fFF <0.300
However,
f: Focal length of the optical system when focusing on an infinite object fFF: Focal length of the front focusing group The optical system according to any one of claims 1 to 17 , which satisfies the following conditional expression.
0.300 <f / fRF <1.10
However,
f: Focal length of the optical system when focusing on an infinite object fRF: Focal length of the rear focusing group The optical system according to any one of claims 1 to 18 , which satisfies the following conditional expression.
0.800 <TL / (Fno ・ Bf) <6.60
However,
TL: Distance from the lens surface to the image plane of the lens located on the most object side when the object is in focus at infinity Fno: Open F number Bf of the optical system: To the image side when the object is in focus at infinity Distance from the image side lens surface of the located lens to the image surface The optical system according to any one of claims 1 to 19 , which satisfies the following conditional expression.
| Ainf-Amod | / f <0.070
However,
Ainf: Half-angle of view of the optical system when focusing on an infinite object Amod: Half-angle of view of the optical system when focusing on the nearest object The front focusing group consists of one positive lens and one negative lens.
The optical system according to any one of claims 1 to 20 , which satisfies the following conditional expression.
30.00 <νFFp-νFFn <75.00
However,
νFFp: Abbe number of the positive lens in the front focusing group νFFn: Abbe number of the negative lens in the front focusing group The optical system according to any one of claims 1 to 21 , which satisfies the following conditional expression.
-1,000 <(FFr2 + FFr1) / (FFr2-FFr1) <2.000
However,
FFr1: Radius of curvature of the object-side lens surface of the positive lens located most on the image side in the front focusing group FFr2: Curvature radius of the image-side lens surface of the positive lens located on the image side of the front focusing group The optical system according to any one of claims 1 to 22 , wherein the front focusing group comprises two or three lenses. The optical system according to any one of claims 1 to 23 , comprising a lens having four or less rear focusing groups. The most image side of the lens is a positive lens, an optical system according to claim 1, any one of 24 which is the second lens is a negative lens from the image side. The optical system according to any one of claims 1 to 25 , which satisfies the following conditional expression.
0.030 <nRBp-nRBn
However,
nRBp: Refractive index of the positive lens in the lens group located most on the image side nRBn: Refractive index of the negative lens in the lens group located on the image side most The optical system according to any one of claims 1 26 image-side lens surface of the lens positioned most image side is convex toward the image side. The optical system according to any one of claims 1 to 27 , which satisfies the following conditional expression.
1.000 <nRBp + 0.005νRBp <2.500
1.000 <nRBn + 0.005νRBn <2.500
However,
nRBp: Refractive coefficient of the positive lens in the lens group located most on the image side nRBn: Refractive coefficient of the negative lens in the lens group located on the image side νRBp: Abbe of the positive lens in the lens group located on the image side most Number νRBn: Abbe number of negative lenses in the lens group located closest to the image side The optical system according to any one of claims 1 to 28 , wherein the front focusing group and the aperture diaphragm are adjacent to each other. The optical system according to any one of claims 1 to 29 , wherein the aperture stop and the rear focusing group are adjacent to each other. The front group, between the front focusing lens group and the aperture stop, is located at the time of focusing to further have a first fixed lens group fixed,
The optical system according to any one of claims 1 to 28 , 30 , wherein the distance between the front focusing group and the first fixed lens group changes at the time of focusing. The rear group further has a second fixed lens group whose position is fixed at the time of focusing between the aperture stop and the rear focusing group.
The optical system according to any one of claims 1 to 29 , 31 , wherein the distance between the rear focusing group and the second fixed lens group changes at the time of focusing. An optical device having the optical system according to any one of claims 1 to 32.

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