JP6406870B2 - Optical system and imaging apparatus having the same - Google Patents

Description

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

  There is a macro lens as an imaging optical system whose main purpose is shooting at a short distance. The macro lens is designed so as to obtain high optical performance at the time of short-distance imaging as compared with an imaging optical system such as a general standard lens or a telephoto lens. In many cases, the macro lens is used not only for short distances but also for imaging a wide range of distances from infinity to short distances.

  In general, in a macro lens, when an attempt is made to expand the focusable imaging distance range (imaging magnification range), a large amount of aberration fluctuations occur due to focusing, particularly on the high magnification side, which is close-up photography, and optical performance deteriorates. . Therefore, in order to correct fluctuations in various aberrations accompanying focusing, a floating system that moves a plurality of lens groups during focusing is used.

  Macro lenses often perform close-up shooting at a high shooting magnification by narrowing the aperture stop to ensure a deep depth of field. For this reason, the shutter speed of the macro lens is slow, and if there is camera shake during shooting, image blurring occurs and the image quality is likely to deteriorate. For this reason, various photographic lenses have been proposed in which some lenses are moved in the direction perpendicular to the optical axis to compensate for image blur during image stabilization (Patent Document 1).

  Patent Document 1 includes first to fifth lens groups having positive, negative, positive, positive, and positive refractive powers in order from the object side to the image side. The second lens group and the fourth lens group are used for focusing. A moving photographic lens is disclosed. The fifth lens group includes a negative refractive power 5a group and a positive refractive power 5b group, and the 5a group is moved in the direction perpendicular to the optical axis during image blur correction.

JP 2009-288384 A

  In recent years, the imaging optical system used in imaging devices has a short minimum imaging distance, high optical performance over the entire object distance, easy image blur correction when the imaging optical system vibrates, and image blur correction. At the time, there is a demand for a decrease in optical performance and the like. In order to obtain high optical performance over the entire object distance, it is important to use an appropriate floating system, and in order to maintain good optical performance during image blur correction, the lens configuration of the subgroup for image blur correction is appropriate. It becomes important to set to.

  An object of the present invention is to provide an optical system that has a shortest imaging distance, high optical performance over the entire object distance, and can maintain good optical performance during image stabilization.

The optical system of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side. An optical system composed of a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power, wherein an interval between adjacent lens groups changes during focusing,
The third lens group is composed of a first partial group and a second partial group,
The second lens group and the fourth lens group move to the image side during focusing from infinity to a short distance,
During focusing, the first lens group, the aperture stop, and the third lens group are stationary,
Either one of the first partial group and the second partial group is an anti-vibration group that moves so as to include a component in a direction perpendicular to the optical axis during image blur correction,
The focal length of the anti-vibration group is fs, the focal length of the entire system when focusing at infinity is finf , the lateral magnification of the second lens group when focusing at infinity is β2inf, and the imaging magnification is When the lateral magnification of the second lens group is β2 mod when focusing on an object distance of equal magnification ,
0.5 <fs / finf <1.5
1.0 <β2inf / β2mod <10.0
It satisfies the following conditional expression.

  According to the present invention, an optical system is obtained in which the shortest imaging distance is short, the optical performance is high over the entire object distance, and the optical performance during image stabilization can be maintained well.

(A), (B) Lens cross-sectional view when the optical system of Example 1 of the present invention is at infinity and the photographing magnification is equal. (A), (B) Aberration diagram when the optical system of Example 1 of the present invention is at infinity and the photographing magnification is equal. (A), (B) In the optical system according to Example 1 of the present invention, aberration diagrams when the image infinity is corrected at an infinite distance and the imaging magnification is equal when the image blur whose optical axis is inclined by 0.4 ° is corrected. (A), (B) Lens cross-sectional view when the optical system of Example 2 of the present invention is at infinity and the photographing magnification is equal. (A), (B) Aberration diagrams when the optical system of Example 2 of the present invention is at infinity and the photographing magnification is equal. (A), (B) In the optical system of Example 2 of the present invention, aberration diagrams when the image axis is corrected at infinity when the optical axis is tilted by 0.4 ° and when the imaging magnification is equal. Schematic diagram of main parts of an imaging apparatus of the present invention

The optical system of the present invention and the image pickup apparatus having the same will be described below. The optical system of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a negative lens disposed in order from the object side to the image side. The lens unit includes a fourth lens unit having a refractive power and a fifth lens unit having a positive refractive power. The distance between adjacent lens groups changes during focusing. The third lens group is composed of a first partial group and a second partial group. During focusing from infinity to a short distance, the second lens group and the fourth lens group move to the image side. During focusing, the first lens group, the aperture stop, and the third lens group do not move. One of the first partial group and the second partial group is a vibration-proof group that moves so as to include a component in a direction perpendicular to the optical axis during image blur correction.

  The lens group in the optical system according to the present invention can be divided according to a change in the lens interval accompanying focusing. Each lens group constituting the optical system of the present invention may be composed of one or more lenses, and is not limited to being composed of a plurality of lenses.

  FIGS. 1A and 1B are lens cross-sectional views when the infinite distance and the imaging magnification are equal in the optical system according to the first embodiment of the present invention. FIGS. 2A and 2B are longitudinal aberration diagrams when the optical system of Example 1 is at infinity and the imaging magnification is equal. FIGS. 3A and 3B show that the image magnification is equal to infinity when image blur is corrected with the optical axis tilted by 0.4 degrees in the optical system of Example 1 (during image stabilization). FIG. Example 1 is an optical system having an F number of 3.50 and an imaging field angle of 28.52 degrees.

  4A and 4B are lens cross-sectional views when the infinite distance and the imaging magnification are equal in the optical system according to the second embodiment of the present invention. 5A and 5B are longitudinal aberration diagrams in the optical system of Example 2 when the infinity and the imaging magnification are equal. FIGS. 6A and 6B show that the image magnification is equal to infinity when image blur is corrected with the optical axis tilted by 0.4 degrees in the optical system of Example 2 (during image stabilization). FIG. Example 2 is an optical system having an F number of 3.50 and an imaging field angle of 31.08 degrees. FIG. 7 is a schematic view of the main part of the imaging apparatus of the present invention.

  In the lens cross-sectional view, the left side is the object side (front, enlargement side), and the right side is the image side (rear, reduction side). OL is an optical system, and in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, an aperture stop SP, and a third lens unit having a positive refractive power. L3 includes a fourth lens unit L4 having a negative refractive power and a fifth lens unit L5 having a positive refractive power.

  IP is an image plane. When the optical system of the present invention is used as an imaging optical system of a video camera or a digital still camera, the image plane IP is an image of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor. It corresponds to a surface. When the optical system of the present invention is used as an optical system for a silver salt film camera, the image plane IP corresponds to a film surface. In the spherical aberration diagram, d represents the d line, C represents the C line, g represents the g line, and F represents the F line. In the graph showing astigmatism, dM represents a meridional image plane for d line, dS represents a sagittal image plane for d line, gM represents a meridional image plane for g line, and gS represents a sagittal image plane for g line. Distortion is represented by d-line.

  In the lateral chromatic aberration diagram, C represents the C line, g represents the g line, and F represents the F line. Fno is an F number. In each lateral aberration diagram, dM represents a d-line meridional ray, and dS represents a d-line sagittal ray.

In Example 1, the third lens unit L3 includes a partial group (first partial group) L3a and a partial group (second partial group) L3b which are arranged in order from the object side to the image side. The subgroup L3a is composed of one positive lens. The sub-group L3b is a vibration-proof group that includes a cemented lens in which a positive lens and a negative lens are cemented, and moves so as to include a component in a direction perpendicular to the optical axis during image blur correction. During focusing, the first lens unit L1, the third lens unit L3, and the fifth lens unit L5 do not move. During focusing from infinity to a short distance, the second lens unit L2 and the fourth lens unit L4 move to the image side. At the time of focusing, the aperture stop SP does not move as shown in the lens cross-sectional view and numerical data described later.

  In the first embodiment, the third lens unit L3 or the fourth lens unit L4 may be moved so as to have a component in a direction perpendicular to the optical axis when correcting the image blur.

In Example 2, the third lens unit L3 includes a partial group (first partial group) L3a and a partial group (second partial group) L3b which are arranged in order from the object side to the image side. The partial group L3a is composed of one positive lens, and is a vibration-proof group that moves so as to include a component in a direction perpendicular to the optical axis when image blur correction is performed. The partial system L3b includes a cemented lens in which a positive lens and a negative lens are cemented. During focusing, the first lens unit L1 and the third lens unit L3 do not move. During focusing from infinity to short distance, the second lens unit L2 and the fourth lens unit L4 move toward the image side, and the fifth lens unit L5 moves along a convex locus toward the object side.

  The characteristics of the lens configuration of the optical system of each example will be described. A focusing type is employed in which the second lens unit L2 having a negative refractive power and the fourth lens unit L4 having a negative refractive power are moved to the image side during focusing from infinity to a short distance. By disposing the third lens unit L3 having a positive refractive power in the vicinity of the aperture stop SP, the effective diameter of the third lens unit L3 is reduced. Further, the effective diameter of the fourth lens unit L4 is reduced by converging the light rays with the third lens unit L3. Then, all or a part of the third lens unit L3 is set as an anti-vibration unit, and is moved so as to have a component in a direction perpendicular to the optical axis at the time of image blur correction.

The focal length of the anti-vibration group is fs, and the focal length of the entire system when focusing at infinity is finf. At this time,
0.5 <fs / finf <1.5 (1)
The following conditional expression is satisfied.

  Conditional expression (1) is an expression relating to the focal length of the image blur correction subgroup (hereinafter also referred to as “anti-vibration group”). If the positive power of the anti-vibration group becomes weaker than the upper limit of the conditional expression (1), the anti-vibration sensitivity decreases, the amount of eccentricity required for image blur correction increases, and the entire system increases in size. come. If the lower limit of the conditional expression (1) is exceeded and the positive power of the image stabilizing group becomes strong, the curvature of field increases at the time of image blur correction, and this correction becomes difficult.

  As described above, according to the present invention, an optical system capable of photographing up to near the same magnification, optically compensating for image blur due to camera shake, and maintaining good optical performance during image stabilization. Is obtained.

In each embodiment, it is more preferable to satisfy one or more of the following conditional expressions. However, the focal length of the first lens unit L1 is f1, the focal length of the second lens unit L2 is f2, the focal length of the third lens unit L3 is f3, and the focal length of the fourth lens unit L4 is f4. Further, when the focal length is infinity, the lateral magnification of the second lens unit L2 is β2inf, and when the focal length is an object distance where the photographing magnification is the same magnification (the photographing magnification is -1 times) (closest distance) Distance) The lateral magnification of the second lens unit L2 is β2 mod. Further, the lateral magnification of the fourth lens unit L4 when focused at infinity is β4inf, and the lateral magnification of the fourth lens unit L4 when focusing on the object distance at which the imaging magnification is equal is β4mod. To do.

Further, the amounts of movement of the second lens unit L2 and the fourth lens unit L4 at the time of focusing from infinity to the closest distance are m2 and m4, respectively. The sign of the amount of movement is positive when the lens group moves to the image side when focusing on a close distance compared to when focusing on infinity. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.2 <f3 / finf <2.0 (2)
−1.0 <f2 / finf <−0.2 (3)
−1.0 <f4 / finf <−0.2 (4)
1.0 <β2inf / β2mod <10.0 (5)
1.0 <β4inf / β4mod <10.0 (6)
0.1 <f1 / finf <1.0 (7)
−0.80 <m2 / f2 <−0.22 (8)
−0.80 <m4 / f4 <−0.22 (9)

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (2) relates to the focal length of the third lens unit L3. If the positive power of the third lens unit L3 becomes weaker than the upper limit of the conditional expression (2), the force for converging light rays becomes weak, and the entire system becomes large. When the positive power of the third lens unit L3 increases beyond the lower limit of conditional expression (2), it becomes difficult to keep various aberrations in good condition.

  Conditional expression (3) relates to the focal length of the second lens unit L2. When the negative power of the second lens unit L2 increases beyond the upper limit of conditional expression (3) (when the absolute value of the negative refractive power increases), it becomes difficult to maintain various aberrations satisfactorily. If the lower power of the conditional expression (3) is exceeded and the negative power of the second lens unit L2 becomes weak (the absolute value of the negative refractive power decreases), the amount of movement during focusing increases and the total lens length increases. .

  Conditional expression (4) relates to the focal length of the fourth lens unit L4. When the negative power of the fourth lens unit L4 is increased beyond the upper limit of conditional expression (4), it becomes difficult to keep various aberrations in good condition. When the negative power of the fourth lens unit L4 becomes weaker beyond the lower limit of conditional expression (4), the amount of movement during focusing increases and the total lens length increases.

  Conditional expression (5) relates to the lateral magnification of the second lens unit L2 for focusing. If the change in the lateral magnification increases beyond the upper limit of conditional expression (5), it becomes difficult to maintain various aberrations satisfactorily. If the change in the lateral magnification becomes smaller than the lower limit of conditional expression (5), the amount of movement of the second lens unit L2 during focusing increases, and the entire system becomes larger.

  Conditional expression (6) relates to the lateral magnification of the fourth lens unit L4 for focusing. If the change in lateral magnification increases beyond the upper limit of conditional expression (6), it becomes difficult to keep various aberrations in good condition. When the lateral magnification is reduced beyond the lower limit of conditional expression (6), the amount of movement of the fourth lens unit L4 during focusing increases, and the entire system becomes larger.

  Conditional expression (7) relates to the focal length of the lens unit (first lens unit L1) having a positive refractive power arranged on the most object side. When the upper limit of conditional expression (7) is exceeded, the force for converging the light beam becomes weak, and the total lens length increases. If the lower limit of conditional expression (7) is exceeded and the positive refractive power of the first lens unit L1 becomes too strong, various aberrations increase and the entire system becomes large.

  Conditional expression (8) relates to the amount of movement and the focal length during focusing of the second lens unit L2. When the absolute value of the negative refractive power of the second lens unit L2 becomes smaller than the upper limit of conditional expression (8) (when the negative refractive power becomes smaller), the amount of movement of the lens unit during focusing increases, and the total lens length increases. It will turn. Further, when the absolute value of the negative refractive power of the second lens unit L2 exceeds the lower limit of conditional expression (8) (when the negative refractive power increases), the variation of various aberrations increases, and the optical performance is improved. It becomes difficult to keep.

  Conditional expression (9) relates to the amount of movement and the focal length during focusing of the fourth lens unit L4. When the absolute value of the negative refracting power of the fourth lens unit L4 becomes smaller than the upper limit of the conditional expression (9) (when the negative refracting power becomes smaller), the amount of movement of the lens unit during focusing increases, and the total lens length becomes large. It will turn. Further, when the absolute value of the negative refractive power of the fourth lens unit L4 exceeds the lower limit of conditional expression (9) (when the negative refractive power increases), various aberrations increase, and the optical performance is improved. It becomes difficult to keep. Furthermore, it is preferable to set the numerical ranges of the conditional expressions (1) to (7) as follows.

0.8 <fs / finf <1.3 (1a)
0.2 <f3 / finf <0.5 (2a)
−0.40 <f2 / finf <−0.25 (3a)
−0.8 <f4 / finf <−0.4 (4a)
1.0 <β2inf / β2mod <3.9 (5a)
1.0 <β4inf / β4mod <3.9 (6a)
0.40 <f1 / finf <0.63 (7a)
−0.60 <m2 / f2 <−0.30 (8a)
−0.60 <m4 / f4 <−0.30 (9a)

  As described above, according to each embodiment, an optical system having an image stabilization function that can easily perform short-distance shooting (macro shooting) with a shooting magnification of approximately the same magnification and that optically compensates for image blur due to camera shake or the like. Is obtained.

  Next, an embodiment of a single-lens reflex camera system using the optical system of the present invention will be described with reference to FIG. In FIG. 7, reference numeral 10 denotes a single-lens reflex camera body, and 11 denotes an interchangeable lens equipped with an optical system according to the present invention. Reference numeral 12 denotes recording means such as a film for recording a subject image obtained through the interchangeable lens 11 and an imaging element (photoelectric conversion element). Reference numeral 13 denotes a finder optical system for observing the subject image from the interchangeable lens 11, and reference numeral 14 denotes a quick return mirror that rotates to selectively guide the light from the interchangeable lens 11 to the recording means 12 and the finder optical system 13.

  When observing the subject image with the finder, the subject image formed on the focusing plate 15 via the quick return mirror 14 is made into an erect image with the pentaprism 16 and then magnified and observed with the eyepiece optical system 17. At the time of shooting, the quick return mirror 14 rotates in the direction of the arrow, and the subject image is formed and recorded on the recording means 12. Reference numeral 18 denotes a submirror, and 19 denotes a focus detection device. Thus, by applying the optical system of the present invention to a single-lens reflex camera interchangeable lens, an imaging apparatus having high optical performance can be realized.

  The present invention can be similarly applied to a single-lens camera with a mirror lens without a quick return mirror, and is not limited to the above.

  Next, numerical examples corresponding to the respective examples will be shown. In the numerical example of each embodiment, j represents a surface number counted from the object side, and rj is a radius of curvature of the jth surface number. dj represents the distance between the j-th surface and the (j + 1) -th surface on the optical axis, and ndj and νdj represent the refractive index and Abbe number of the j-th optical material with respect to the d-line. Indicates the focal length, F number, half angle of view (degrees), and image height of the optical system. The total lens length is the distance from the first lens surface to the image plane. BF is a back focus, which is a distance from the final lens surface to the image plane.

In addition, the aspherical surface is provided with a symbol * after the surface number. In the aspherical shape, X is the amount of displacement from the surface apex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, A4, A6, When A8 is an aspheric coefficient of each order,
x = (h ² / R) / [1+ {1− (1 + k) (h / R) ² }] ^1/2 + A4 · H ⁴ ++ A6 · H ⁶ + A8 · H ⁸
Represented by Note that “E ± XX” in each aspheric coefficient means “× 10 ^{± XX} ”.
Table 1 shows the values of the conditional expressions in each numerical example.

(Numerical example 1)
Unit mm

Surface data surface number rd nd νd
1 32.481 3.23 1.65 160 58.5
2 -79.222 0.15
3 21.104 3.68 1.62299 58.2
4 -34.926 1.30 1.84666 23.8
5 71.129 (variable)
6 98.063 1.00 1.83400 37.2
7 13.481 2.53
8 -17.717 1.10 1.76200 40.1
9 19.466 2.94 1.84666 23.8
10 -34.587 (variable)
11 ∞ 1.20
12 -233.884 1.94 1.78800 47.4
13 -25.391 1.09
14 40.302 2.74 1.69680 55.5
15 -18.763 1.20 1.67270 32.1
16 -1222.568 (variable)
17 -38.346 1.22 1.84666 23.8
18 -20.374 1.00 1.69 100 54.8
19 * 57.221 (variable)
20 34.413 5.15 1.60311 60.6
21 -25.255 2.05
22 -20.820 1.24 1.84666 23.8
23 483.717 17.69
Image plane ∞

Aspheric data 19th surface
K = 0.00000e + 000 A 4 = -7.30784e-006 A 6 = 1.17385e-008 A 8 = -1.90930e-010

Focal length 53.73
F number 3.50
Half angle of view (degrees) 14.26
Statue height 13.66
Total lens length 76.39
BF 17.69

Magnification ∞ -0.5 -1
d 5 0.93 4.19 8.29
d10 8.52 5.25 1.16
d16 1.53 7.18 13.34
d19 12.97 7.32 1.15

Group data group Start surface Focal length
1 1 24.13
2 6 -15.75
3 11 21.63
4 17 -37.48
5 20 284.09

(Numerical example 2)
Unit mm

Surface data surface number rd nd νd
1 28.805 2.99 1.81600 46.6
2 -157.289 0.15
3 23.902 3.30 1.58913 61.1
4 -36.290 1.30 1.84666 23.8
5 49.940 (variable)
6 50.781 0.80 1.83481 42.7
7 12.747 2.04
8 -25.722 0.80 1.83400 37.2
9 9.616 3.00 1.84666 23.8
10 -109.053 (variable)
11 (Aperture) ∞ 1.19
12 118.672 1.81 1.69680 55.5
13 -51.169 1.19
14 43.271 3.38 1.78800 47.4
15 -13.825 1.20 1.84666 23.8
16 -36.999 (variable)
17 -31.839 1.18 1.84666 23.8
18 -19.553 1.00 1.69 100 54.8
19 * 40.901 (variable)
20 76.091 4.02 1.81600 46.6
21 -25.398 3.87
22 -18.468 1.24 1.84666 23.8
23 -53.565 (variable)
Image plane ∞

Aspheric data 19th surface
K = 0.00000e + 000 A 4 = -3.47975e-006 A 6 = -1.28602e-007 A 8 = 1.52010e-009

Focal length 49.11
F number 3.50
Half angle of view (degrees) 15.54
Statue height 13.66
Total lens length 85.40
BF 26.90

Magnification ∞ -0.5 -1
d 5 0.97 4.09 8.32
d10 8.70 5.55 1.35
d16 1.23 7.79 14.23
d19 13.14 7.56 1.25
d23 26.90 25.93 25.80

Group data group Start surface Focal length
1 1 26.83
2 6 -13.75
3 11 18.74
4 17 -27.88
5 20 56.82

L1 1st lens group L2 2nd lens group L3 3rd lens group L3a Partial group L3b Partial group L4 4th lens group L5 5th lens group

Claims (10)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, a third lens group having a positive refractive power, and a first lens group having a negative refractive power, which are arranged in order from the object side to the image side. An optical system composed of four lens groups and a fifth lens group having a positive refractive power, wherein the distance between adjacent lens groups changes during focusing;
The third lens group is composed of a first partial group and a second partial group,
The second lens group and the fourth lens group move to the image side during focusing from infinity to a short distance,
During focusing, the first lens group, the aperture stop, and the third lens group are stationary,
Either one of the first partial group and the second partial group is an anti-vibration group that moves so as to include a component in a direction perpendicular to the optical axis during image blur correction,
The focal length of the anti-vibration group is fs, the focal length of the entire system when focusing at infinity is finf , the lateral magnification of the second lens group when focusing at infinity is β2inf, and the imaging magnification is When the lateral magnification of the second lens group is β2 mod when focusing on an object distance of equal magnification ,
0.5 <fs / finf <1.5
1.0 <β2inf / β2mod <10.0
An optical system that satisfies the following conditional expression: When the focal length of the third lens group is f3,
0.2 <f3 / finf <2.0
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the second lens group is f2,
−1.0 <f2 / finf <−0.2
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the fourth lens group is f4,
−1.0 <f4 / finf <−0.2
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the lateral magnification of the fourth lens group when focused at infinity is β4inf, and when the lateral magnification of the fourth lens group is focused at an object distance at which the photographing magnification is equal, β4mod ,
1.0 <β4inf / β4mod <10.0
Optical system according to any one of claims 1 to 4, characterized by satisfying the conditional expression. When the focal length of the first lens group is f1,
0.1 <f1 / finf <1.0
Optical system according to any one of claims 1 to 5, characterized by satisfying the conditional expression. The focal length of the second lens group is f2, and the amount of movement of the second lens group when focusing from infinity to the closest distance is m2. When the sign of the amount of movement when the second lens group moves to the image side when in focus is positive,
−0.80 <m2 / f2 <−0.22
Optical system according to any one of claims 1 to 6, characterized by satisfying the conditional expression. The focal length of the fourth lens group is f4, and the amount of movement of the fourth lens group during focusing from infinity to the closest distance is m4, which is closer to the closest distance than when focusing on infinity. When the sign of the amount of movement when the fourth lens group moves to the image side when in focus is positive,
−0.80 <m4 / f4 <−0.22
Optical system according to any one of claims 1 to 7, characterized by satisfying the conditional expression. The third lens group is composed of the first partial group and the second partial group, which are arranged in order from the object side to the image side, and the first partial group is composed of one positive lens, and the second part The optical system according to any one of claims 1 to 8 , wherein the group includes a cemented lens in which a positive lens and a negative lens are cemented. An optical system according to any one of claims 1 to 9, the imaging apparatus characterized by having a photoelectric conversion element for receiving an image formed by the optical system.