JP5546387B2 - Teleconverter and photographing optical system having the same - Google Patents

Description

The present invention relates to a main lens system of the rear detachably attached to and teleconverter displacing the focal length of the entire lens system in the longer shooting optical system having it (image side). The present invention is particularly suitable for imaging devices such as digital cameras, video cameras, electronic still cameras, TV cameras, and silver halide photography cameras.

The focus of prior art, single-lens reflex interchangeable lenses flex camera (main lens system) (imaging lens) and a lens having a negative focal length between the camera body (power) (teleconverter) detachably attached to the entire system of It is widely practiced to move the distance longer. This method has advantages that the focal length of the entire lens system can be easily displaced, and that the entire lens system can be made compact compared to a method of mounting on the object side of the main lens system. However, this system increases the open F number of the entire system in proportion to the magnification of the focal length of the entire system, that is, the brightness of the entire lens system decreases.

Further, when a teleconverter is attached to the main lens system, the residual aberration of the main lens system is increased in proportion to the enlargement magnification. For this reason, in many cases, when a teleconverter is attached to the main lens system, the image quality deteriorates . For example when the enlargement magnification when mounting the teleconverter to the main lens system is two-fold, lateral aberration in image quality is enlarged to twice lowered. Longitudinal aberrations are magnified to the square of the magnification, that is, four times. However, in the case of a teleconverter , the F number of the main lens system is also doubled. Eventually longitudinal aberrations are also magnified and reduced by a factor of 2 per unit depth of focus.

Therefore, in order to maintain good aberrations of the entire system when fitted with a teleconverter to the main lens system, it is necessary to satisfactorily correct various aberrations teleconverter itself. Conventionally, there is known a teleconverter that maintains good optical performance when mounted on a main lens system by optimizing power arrangement (refractive power arrangement), lens configuration, and the like (Patent Documents 1 and 2).

JP 63-147127 A JP 2009-80176 A

When attached to the main lens system, teleconverter method for displacing the focal length of the entire system to longer has a negative refractive power. For this reason, since it itself has a large negative Petzval sum, when it is attached to the main lens system, the field curvature often decreases . Further, when mounting the teleconverter to the main lens system, since the aperture stop has the main lens system, in many cases, it is used aperture in the main lens system. Therefore, within the teleconverter, without principal ray of the off-axis light flux intersects the optical axis, so passing through the upper and lower optical axis.

Therefore, teleconverter It is generally difficult to offset various aberrations occurring by passage through outside the optical axis. Spherical aberration when mounting the teleconverter to the main lens system, coma, the correction of the field curvature is relatively easy, the correction of lateral chromatic aberration becomes difficult.

An object of the present invention is to provide a teleconverter that can easily maintain high optical performance even when attached to a main lens system, and a photographing optical system having the teleconverter.

The teleconverter of the present invention is a teleconverter mounted on the image side of the main lens system, and the teleconverter has a negative refractive power, and has the widest air interval among the lens surface intervals of the teleconverter. The rear group, which is an optical system disposed on the image side, is composed of a lens unit RL1 having a positive refractive power, a lens group RL2 having a negative refractive power, and a lens group RL3 having a positive refractive power in order from the object side to the image side. The lens group RL2 is composed of a single negative lens, and the focal length of the i-th positive lens and the Abbe number of the material counted from the object side of the rear group are Rfpi, Rνdpi, and the focal point of the teleconverter, respectively. When the distance is f , and the Abbe number and partial dispersion ratio of the negative lens material are Rνd2n and RθgF2n, respectively .
5 <Σ (Rfpi × Rνdpi) / | f | <54
0 <RθgF2n−0.6438 + 0.001682 × Rνd2n <0.05
It satisfies the following conditional expression.
In addition, the teleconverter of the present invention is a teleconverter mounted on the image side of the main lens system, and the teleconverter has a negative refractive power, and is the widest distance between the lens surfaces of the teleconverter. The rear group, which is an optical system arranged on the image side of the air gap, is arranged in order from the object side to the image side, a positive refractive power lens group RL1, a negative refractive power lens group RL2, and a positive refractive power lens group. The lens group RL3 includes a negative lens, and the focal length of the i-th positive lens and the Abbe number of the material counted from the object side of the rear group are Rfpi, Rνdpi, and the focal point of the teleconverter, respectively. When the distance is f , and the Abbe number and partial dispersion ratio of the negative lens material are Rνd3n and RθgF3n, respectively .
5 <Σ (Rfpi × Rνdpi) / | f | <54
0.00 <RθgF3n−0.6438 + 0.001682 × Rνd3n <0.05
It satisfies the following conditional expression.

According to the present invention, the main lens teleconverter and the imaging optical system having the same high optical performance even when worn it can be easily maintained in the system is obtained.

Lens sectional view when mounting the numeric teleconverter Example 1 in the main lens system Lens cross section of teleconverter of Numerical Example 1 Aberration view when mounting the numeric teleconverter Example 1 in the main lens system Lens cross section of teleconverter of Numerical Example 2 Aberration view when mounting the numeric teleconverter Example 2 in the main lens system Lens sectional view of teleconverter of Numerical Example 3 Aberration view when mounting the teleconverter numerical example 3 in the main lens system Schematic diagram of main parts of an imaging apparatus of the present invention

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Teleconverter of the present invention, has a negative focal length to be displaced to longer than and detachably attached to the image surface side of the main lens system focal length of the entire system to the focal length of the main lens system itself Yes. The teleconverter is composed of a front group and a rear group in order from the object side to the image side, with the widest air interval among the lens surface intervals . The front group consists of one or two lens groups. The rear group includes an RL1 lens group having a positive refractive power, an RL2 lens group having a negative refractive power, and an RL3 lens group having a positive refractive power.

Figure 1 is a lens sectional view of the entire system when a teleconverter of Example 1 of the present invention is detachably attached to the image surface side of the main lens system. Although the telephoto lens is mentioned here as an example of the main lens system, the main lens system is not limited to the present embodiment, and any lens system such as a zoom lens or a standard lens may be used.

Figure 2 is a lens sectional view of a single teleconverter Example 1 of the present invention. FIG. 3 is an aberration diagram for photographing the entire system at infinity when the teleconverter of Example 1 is attached to the main lens system. Figure 4 is a single lens sectional view of a teleconverter Example 2 of the present invention, FIG 5 is aberration diagrams in the infinity object image pickup of the entire system when fitted with a teleconverter of Example 2 in the main lens system is there. Figure 6 is a single lens sectional view of a teleconverter Example 3 of the present invention, FIG. 7 is aberration diagrams in the infinity object image pickup of the entire system when fitted with a teleconverter of Example 3 in the main lens system is there.

A lens system in which a teleconverter is attached to the main lens system of each embodiment is a photographing lens system used in an imaging apparatus such as a digital still camera or a silver halide film camera. In the lens cross-sectional view, the left side is the subject side (front), and the right side is the image side (rear).

In Figure 1, ML is the main lens system, RCL is teleconverter, OL the main lens system lens system fitted with a teleconverter RCL in ML (entire system) (imaging optical system). In the main lens system ML, SP is an aperture stop, and G is an optical block corresponding to protective glass or the like. In the teleconverter RCL, FS is a flare cut stop. IP is an image plane. When used as a photographing optical system for a video camera or a digital still camera, an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor, or a camera for a silver salt film It corresponds to a photosensitive surface such as a film surface.

In the aberration diagrams, d and g are d-line and g-line, and S · C is a sine condition. M and S are the d-line meridional image surface and sagittal image surface. Lateral chromatic aberration is represented by the g-line. Fno is the F number, and ω is the shooting half field angle. The teleconverter RCL of each embodiment is arranged on the image side having the widest air interval among the intervals between the front surface LF and the lens surface, which is an optical system arranged on the object side having the widest air interval among the lens surface intervals. The rear group RL is an optical system. The front group FL includes a lens group FL1 and a lens group FL2. The rear group RL includes a lens unit RL1 having a positive refractive power, a lens group RL2 having a negative refractive power, and a lens group RL3 having a positive refractive power.

Here, the lens group refers to lenses separated by a finite air interval, such as a single lens or a cemented lens obtained by cementing a plurality of lenses.

In teleconverter RCL of each embodiment, the i-th positive lens focal length and the material of the Abbe number, respectively Rfpi counted from the object side of the rear group RL, and Arunyudpi. Further, the focal length of the telephoto converter RCL and f. At this time,
5 <Σ (Rfpi × Rνdpi) / | f | <54 (1)
The following conditional expression is satisfied.

Embodiments of teleconverter RCL relatively close lens group to the image plane in RL1, lens group RL2, the group RL after consisting lens RL3 is higher incidence height of the off-axis ray. Therefore, this lens group is suitable for correcting lateral chromatic aberration. Therefore, in each embodiment, the chromatic aberration of magnification is satisfactorily corrected while suppressing the occurrence of field curvature so as to satisfy the conditional expression (1) with respect to the focal length of the positive lens constituting the rear group RL and the Abbe number of the material. Yes.

Conditional expression (1) relates to achromaticity in the rear group RL. When the lower limit of conditional expression (1) is exceeded, achromaticity due to the positive lens becomes too small, making it difficult to correct lateral chromatic aberration. If the upper limit of conditional expression (1) is exceeded, the achromaticity by the positive lens becomes too large, and the lateral chromatic aberration is overcorrected, which is not good. Conditional expression (1) is more preferably set as follows.

10 <Σ (Rfpi × Rνdpi) / | f | <52 (1a)
As described above, according to the teleconverter of the present invention, the chromatic aberration of magnification is corrected particularly well, and high optical performance can be obtained even when mounted on the main lens system.

In teleconverter of each embodiment, when mounted to the main lens system ML, in order to maintain a more excellent optical performance, to satisfy one or more of the following conditions. The RL2 lens group RL2 includes a single negative lens, and the Abbe number and the partial dispersion ratio of the negative lens material are Rνd2n and RθgF2n, respectively. The lens group RL3 has a negative lens, and the Abbe number and the partial dispersion ratio of the material of the negative lens are Rνd3n and RθgF3n, respectively. Let Rr2r be the radius of curvature of the lens surface closest to the image side of the lens group RL2 , and Rr3f be the radius of curvature of the lens surface closest to the object side of the lens group RL3 .

Let Rr1r be the radius of curvature of the lens surface closest to the image side of the lens group RL1 , and Rr2f be the radius of curvature of the lens surface closest to the object side of the lens group RL2 . The front group FL has one or more lens groups, and the distance on the optical axis from the most image side lens surface of the front group FL to the object side lens surface of the lens group RL1 is dfr. The length of the optical axis of the teleconverter RCL and td. The radius of curvature of the lens surface closest to the image side of the lens group FL1 is Fr1r, and the radius of curvature of the lens surface closest to the object side of the lens group FL2 is Fr2f.

At this time,
0 <RθgF2n−0.6438 + 0.001682 × Rνd2n <0.05
... (2)
0.00 <RθgF3n−0.6438 + 0.001682 × Rνd3n <0.05
... (3)
0.03 <(Rr2r−Rr3f) / (Rr2r + Rr3f) <0.25
... (4)
−0.30 <(Rr1r−Rr2f) / (Rr1r + Rr2f) <− 0.07
... (5)
0.08 <dfr / td <0.27 (6)
0.03 <(Fr1r−Fr2f) / (Fr1r + Fr2f) <0.25
... (7)
It is preferable to satisfy one or more of the following conditional expressions.

Next, the technical meaning of each conditional expression described above will be described. Conditional expression (2) relates to partial dispersion of the material of the negative lens disposed in the lens group RL2 . If the partial dispersion of the material of the negative lens is too small beyond the lower limit of conditional expression (2), the effect of correcting the lateral chromatic aberration is not likely to be small. If the upper limit of conditional expression (2) is exceeded and the partial dispersion of the material of the negative lens becomes too large, the glass material that can be selected is likely to decrease. Conditional expression (2) is more preferably set as follows.

0.01 <RθgF2n−0.6438 + 0.001682 × Rνd2n <0.04
... (2a)
Conditional expression (3) relates to partial dispersion of the material of the negative lens arranged in the lens group RL3 .

If the partial dispersion of the material of the negative lens is too small beyond the lower limit of conditional expression (3), the effect of correcting the lateral chromatic aberration is not likely to be small. If the upper limit of conditional expression (3) is exceeded and the partial dispersion of the negative lens material becomes too large, the glass material that can be selected is likely to be small. Conditional expression (3) is more preferably set as follows.

0.01 <RθgF3n−0.6438 + 0.001682 × Rνd3n <0.04
... (3a)
Conditional expression (4) relates to the shape of the air lens between the lens group RL2 and the lens group RL3 .

If the lower limit of conditional expression (4) is exceeded, the field curvature will not be good. If the upper limit of conditional expression (4) is exceeded, the field curvature will not be good. Conditional expression (4) is more preferably set as follows.

0.05 <(Rr2r−Rr3f) / (Rr2r + Rr3f) <0.22
... (4a)
Conditional expression (5) relates to the shape of the air lens between the lens group RL1 and the RL2 group RL2. If the lower limit of conditional expression (5) is exceeded, the field curvature will not be good. If the upper limit of conditional expression (5) is exceeded, negative distortion is not likely to increase. Conditional expression (5) is more preferably set as follows.

−0.26 <(Rr1r−Rr2f) / (Rr1r + Rr2f) <− 0.09
... (5a)
Conditional expressions (4) and (5) should be satisfied at the same time, and an appropriate balance should be achieved. According to this, it becomes easy to correct field curvature and distortion more satisfactorily.

Condition (6) is teleconverter RCL length on the optical axis, i.e., from the most object side lens surface and the lens group FL2 to the lens surface on the most image side with respect to the length on the optical axis spacing of the RL1 lens group With respect to the ratio. If the distance dfr is too small beyond the lower limit of conditional expression (6), the rear group RL approaches the stop SP of the main lens ML, so that the separation between the on-axis light beam and the off-axis light beam is reduced, and the lateral chromatic aberration is effectively reduced. It becomes difficult to correct. If the upper limit of condition (6), not good because it is difficult to place the desired lens group for the proportion of the interval dfr the total lens length of the teleconverter RCL is too large. Conditional expression (6) is more preferably set as follows.

0.085 <dfr / td <0.250 (6a)
The lens group FL1 and the lens group FL2 of the front group FL have a relatively high incident height of axial rays, so that it is easy to effectively correct spherical aberration and axial chromatic aberration.

Conditional expression (7) relates to the shape of the air lens between the lens group FL1 and the lens group FL2 . When the lower limit or upper limit of conditional expression (7) is exceeded, it is difficult to correct spherical aberration and axial chromatic aberration in a balanced manner. Conditional expression (7) is more preferably set as follows.

0.04 <(Fr1r−Fr2f) / (Fr1r + Fr2f) <0.22
... (7a)
Each of the lens group RL1 and the lens group RL3 is preferably composed of a cemented lens in which a positive lens and a negative lens are cemented.

According to this, it becomes easy to correct lateral chromatic aberration satisfactorily. The lens group FL1 is preferably composed of a cemented lens in which a positive lens and a negative lens are cemented , and the lens group FL2 is preferably composed of a cemented lens in which a positive lens and a negative lens are cemented . According to this, it becomes easy to correct the longitudinal chromatic aberration remaining when correcting the lateral chromatic aberration in the rear group RL. The front group FL may be composed of only one lens group.

Then the teleconverter of the present invention is mounted to the image side of the main lens system will be described with reference to FIG. 8 an embodiment of a single-lens reflex camera (image pickup apparatus) used as the photographing optical system. 10 is any one teleconverter and the imaging lens having an imaging optical system 1 including the main lens system of Example 1, 2 and 3 (interchangeable lens) in FIG. The photographing optical system 1 is held by a lens barrel 2 that is a holding member.

Reference numeral 20 denotes a camera body, which includes a quick return mirror 3 that reflects the light beam from the photographing lens 10 upward and a focusing screen 4 that is disposed at an image forming position of the photographing lens 10. Further, it has a penta roof prism 5 for converting an inverted image formed on the focusing screen 4 into an erect image, an eyepiece 6 for enlarging the erect image, and the like. Reference numeral 7 denotes a photosensitive surface, on which a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor, or a silver film is disposed as a light receiving means (recording means) for receiving an image. At the time of photographing, the quick return mirror 3 is retracted from the optical path, and an image is formed on the photosensitive surface 7 by the photographing lens 10.

Although the preferred embodiments of the optical system of the present invention have been described above, it is needless to say that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof. For example, the present invention can be applied to an imaging device without a quick return mirror.

Next, numerical examples 1 to 3 of the main lens system and teleconverters corresponding to the examples 1 to 3 are shown. For numerical examples 1 to 3, only teleconverter data is shown. Rs is the most distance from the image side surface to the most object side lens surface of the teleconverter of the main lens system. The main lens system in Numerical Examples 1 to 3 uses a telephoto lens in which each aberration with a focal length of 390 mm is corrected sufficiently satisfactorily. Therefore, if the aberrations in a state of wearing teleconverter to the main lens system far are satisfactorily corrected, even when attached to the other of the lens system, it is possible to obtain good properties with respect to the original optical performance .

In the numerical examples, i indicates the order counted from the object side. ri is the radius of curvature of the i-th optical surface, di is the axial distance between the i-th surface and the (i + 1) -th surface, and ndi and νdi are the i-th and (i + 1) -th surfaces with respect to the d-line, respectively. The refractive index and Abbe number of the medium in between are shown. β denotes the magnification at the time of mounting the teleconverter to the main lens system ML. Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.

[Main lens]

Unit mm

Surface data surface number rd nd νd Effective diameter
1 270.270 14.50 1.48749 70.4 134.51
2 -835.232 31.14 133.96
3 138.907 20.35 1.43387 95.1 118.33
4 -523.327 0.19 116.36
5 -499.366 4.30 1.72047 34.7 116.33
6 310.896 27.04 111.57
7 96.687 14.92 1.43387 95.1 98.15
8 664.543 0.24 96.16
9 63.598 6.00 1.51633 64.1 84.19
10 51.493 24.99 76.37
11 461.177 5.35 1.80809 22.8 70.03
12 -178.181 3.20 1.83400 37.2 69.78
13 117.578 73.69 65.06
14 (Aperture) ∞ 10.03 44.75
15 285.718 7.19 1.72916 54.7 41.58
16 -69.727 2.18 1.84666 23.8 40.79
17 -247.741 0.84 40.02
18 81.104 5.31 1.84666 23.8 38.15
19 -151.144 2.00 1.69680 55.5 37.25
20 41.763 5.33 35.01
21 -163.217 1.70 1.88300 40.8 35.07
22 95.192 2.18 35.79
23 93.284 5.74 1.83400 37.2 37.48
24 -356.898 8.32 38.04
25 63.599 9.04 1.74950 35.3 40.70
26 -95.263 1.87 1.80809 22.8 40.10
27 101.811 11.05 39.24
28 ∞ 2.20 1.48749 70.2 39.72
29 ∞ 27.79 39.79
30 ∞ BF 40.77
Image plane ∞

Various data

Focal length 390.09
F number 2.90
Angle of View 3.17
Statue height 21.64
Total lens length 367.66
BF 39.00

[Numerical Example 1]

Unit mm

Surface data surface number rd nd νd Effective diameter
1 136.661 1.20 1.81600 46.6 22.08
2 19.932 5.97 1.57501 41.5 21.80
3 -46.059 2.78 22.04
4 -41.442 1.20 1.72916 54.7 21.81
5 25.523 5.38 1.61340 44.3 22.72
6 -48.774 10.56 23.21
7 -46.012 1.49 1.85026 32.3 24.07
8 65.320 12.02 1.61340 44.3 25.39
9 -24.563 0.20 27.97
10 -39.870 1.20 1.59282 68.6 27.66
11 61.918 0.20 28.68
12 42.253 9.47 1.48749 70.2 29.57
13 -36.822 2.50 1.59282 68.6 29.79
14 -331.730 30.86

Various data

Focal length -83.98

Front principal point 7.09
Rear principal point position -33.52

RS 17.79
β 1.996

Single lens Data lens Start surface Focal length
1 1 -28.73
2 2 25.02
3 4 -21.50
4 5 28.09
5 7 -31.56
6 8 30.66
7 10 -40.73
8 12 42.01
9 13 -70.09

[Numerical Example 2]

Unit mm

Surface data surface number rd nd νd Effective diameter
1 153.654 1.20 1.88300 40.8 24.00
2 19.178 6.00 1.57501 41.5 20.85
3 -59.856 3.98 21.03
4 -46.053 1.20 1.83481 42.7 21.07
5 36.347 5.08 1.73800 32.3 21.97
6 -37.255 9.83 22.42
7 -33.407 1.50 1.83481 42.7 22.53
8 127.368 7.00 1.65412 39.7 24.06
9 -22.677 0.20 25.22
10 -36.679 1.20 1.59282 68.6 25.04
11 67.265 0.20 25.99
12 44.571 6.00 1.61340 44.3 26.56
13 -39.447 1.50 1.80809 22.8 26.72
14 -567.554 27.33

Focal length -87.27


Front principal point position 5.62
Rear principal point position -26.88

RS 17.79
β 1.988

Single lens Data lens Start surface Focal length
1 1 -24.92
2 2 25.98
3 4 -24.17
4 5 25.68
5 7 -31.57
6 8 29.98
7 10 -39.87
8 12 35.07
9 13 -52.53

[Numerical Example 3]

Unit mm

Surface data surface number rd nd νd Effective diameter
1 43.119 1.20 1.88300 40.8 21.80
2 11.681 8.01 1.62588 35.7 19.20
3 -39.543 2.48 18.80
4 -26.576 1.20 1.88300 40.8 17.60
5 19.128 5.73 1.61340 44.3 17.20
6 -18.945 3.52 17.20
7 -35.911 1.20 1.88300 40.8 15.72
8 25.159 7.16 1.58144 40.8 16.25
9 -13.507 0.20 17.14
10 -16.814 1.20 1.59282 68.6 16.77
11 30.102 0.23 18.00
12 26.729 5.61 1.73800 32.3 18.48
13 -22.968 1.50 1.80809 22.8 18.77
14 229.102 19.43


Focal length -41.91


Front principal point position 12.17
Rear principal point position -13.81

RS 27.79
β 2.779

Single lens Data lens Start surface Focal length
1 1 -18.48
2 2 15.33
3 4 -12.44
4 5 16.46
5 7 -16.60
6 8 16.22
7 10 -18.03
8 12 17.58
9 13 -25.76

FL: front group RL: rear group FL1: lens group FL2: lens group RL1: lens group RL2: lens group RL3: lens group SP: stop FP: flare stopper IP: image plane ML: main imaging lens RCL: teleconverter S : Sagittal image plane M: Meridional image plane d: d line g: g line

Claims (11)

A teleconverter mounted on the image side of the main lens system, the teleconverter having a negative refractive power, and an optical element disposed on the image side having the widest air interval among the lens surface intervals of the teleconverter a is a rear group a system, in order from the object side to the image side, a positive refractive power lens group RL1, negative refractive power lens group RL2, is composed of lens RL3 of positive refractive power, the lens unit RL2 is A negative lens, the focal length of the i-th positive lens and the Abbe number of the material counted from the object side of the rear group are respectively Rfpi, Rνdpi, the focal length of the teleconverter is f 1 , When the Abbe number and the partial dispersion ratio of the material are Rνd2n and RθgF2n ,
5 <Σ (Rfpi × Rνdpi) / | f | <54
0 <RθgF2n−0.6438 + 0.001682 × Rνd2n <0.05
A teleconverter that satisfies the following conditional expression: The lens group RL3 has a negative lens, and when the Abbe number and partial dispersion ratio of the material of the negative lens are Rνd3n and RθgF3n,
0.00 <RθgF3n−0.6438 + 0.001682 × Rνd3n <0.05
The teleconverter according to claim 1, wherein the following conditional expression is satisfied. A teleconverter mounted on the image side of the main lens system, the teleconverter having a negative refractive power, and an optical element disposed on the image side having the widest air interval among the lens surface intervals of the teleconverter a is a rear group a system, in order from the object side to the image side, a positive refractive power lens group RL1, negative refractive power lens group RL2, is composed of lens RL3 of positive refractive power, the lens unit RL3 is A negative lens, the focal length of the i-th positive lens counted from the object side of the rear group and the Abbe number of the material are Rfpi, Rνdpi, the focal length of the teleconverter is f 1 , and the material of the negative lens is When the Abbe number and the partial dispersion ratio are Rνd3n and RθgF3n, respectively
5 <Σ (Rfpi × Rνdpi) / | f | <54
0.00 <RθgF3n−0.6438 + 0.001682 × Rνd3n <0.05
A teleconverter that satisfies the following conditional expression: When the curvature radius of the lens surface closest to the image side of the lens group RL2 is Rr2r, and the curvature radius of the lens surface closest to the object side of the lens group RL3 is Rr3f,
0.03 <(Rr2r−Rr3f) / (Rr2r + Rr3f) <0.25
The teleconverter according to claim 1, wherein the following conditional expression is satisfied. When the radius of curvature of the lens surface closest to the image side of the lens group RL1 is Rr1r, and the radius of curvature of the lens surface closest to the object side of the lens group RL2 is Rr2f,
−0.30 <(Rr1r−Rr2f) / (Rr1r + Rr2f) <− 0.07
The teleconverter according to claim 1, wherein the following conditional expression is satisfied. 6. The teleconverter according to claim 1, wherein each of the lens group RL1 and the lens group RL3 includes a cemented lens in which a positive lens and a negative lens are cemented. The front group which is an optical system arranged on the object side having the widest air gap among the distances between the lens surfaces of the teleconverter has one or more lens groups, and the lens group from the most image side lens surface of the front group When the distance on the optical axis to the lens surface on the object side of the lens group RL1 is dfr and the length on the optical axis of the teleconverter is td,
0.08 <dfr / td <0.27
The teleconverter according to claim 1, wherein the following conditional expression is satisfied. The front group, which is an optical system arranged on the object side having the widest air interval among the lens surface intervals of the teleconverter, is composed of a lens group FL1 and a lens group FL2 in order from the object side to the image side. The group FL1 is composed of a cemented lens in which a positive lens and a negative lens are cemented together, and the lens group FL2 is composed of a cemented lens in which a positive lens and a negative lens are cemented together. Teleconverter. When the curvature radius of the lens surface closest to the image side of the lens group FL1 is Fr1r, and the curvature radius Fr2f of the lens surface closest to the object side of the lens group FL2 is:
0.03 <(Fr1r−Fr2f) / (Fr1r + Fr2f) <0.25
The teleconverter according to claim 8, wherein the following conditional expression is satisfied. An imaging optical system comprising: a main lens system; and the teleconverter according to claim 1 detachably attached to an image side of the main lens system. An imaging apparatus comprising: the imaging optical system according to claim 10; and a light receiving unit that receives an image formed by the imaging optical system.