JP5298671B2 - CONVERTER LENS, OPTICAL DEVICE HAVING THE SAME, AND METHOD FOR EXTENDING FOCAL LENGTH OF MASTER LENS - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a converter lens that has high imaging performance for increasing the focal distance of a mater lens. <P>SOLUTION: The detachable converter lens CL is used by being attached to the image side of the master lens. The lens includes a first lens group G1 and a second lens group G2 of negative refractive power in order from an object side. The first lens group includes, in order from the object side, a first lens L1 of negative refractive power, a second lens L2 of positive refractive power, and a cemented lens SL having a negative lens and a positive lens in that order from the object side. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a converter lens, an optical device having the converter lens, and a method for expanding a focal length of a master lens.

Conventionally, in order to increase the focal length of a telephoto lens or the like, a detachable converter that changes the focal length of all lens systems has been proposed (for example, Patent Document 1).
JP 63-201624 A

  However, conventional converter lenses have insufficient imaging performance. Therefore, an object of the present invention is to provide a converter lens having high imaging performance.

In order to achieve the above object, the present invention is a detachable converter lens that is used by being attached to the image side of a master lens, and includes a first lens having negative refractive power in order from the object side , and positive refracting. providing a second lens having a power, a cemented lens, and a positive meniscus lens having a concave surface directed toward the object side, a converter lens characterized by consisting of a negative meniscus lens having a concave surface directed toward the object side.
In addition, the present invention is a detachable converter lens that is used by being attached to the image side of a master lens, and includes a first lens group and a second lens group having negative refractive power in order from the object side. The first lens group is composed of a first lens having a negative refractive power, a second lens having a positive refractive power, and a cemented lens in order from the object side. A converter lens characterized by satisfying the above is provided.
−0.45 <β × TL / f1 ≦ 0.126
1.40 <β
However,
β: magnification of the converter lens
TL: distance on the optical axis from the most object side lens surface to the most image side lens surface of the converter lens
f1: Focal length of the first lens group

  The present invention also provides an optical apparatus comprising the converter lens.

  According to the present invention, a converter lens having high imaging performance can be provided.

  Hereinafter, a converter lens according to an embodiment of the present invention will be described.

  In general, the converter lens not only increases the focal length of the master lens, but also increases the aberration of the master lens, so that aberration correction is difficult. This becomes more prominent as the enlargement magnification is higher. Therefore, it is necessary to provide sufficient optical performance as the magnification increases.

  The converter lens according to the present embodiment is used by being attached to the image side of the master lens, and is a detachable converter lens, and in order from the object side, a first lens group having negative refractive power, and negative refractive power The first lens group includes, in order from the object side, a first lens having negative refractive power, a second lens having positive refractive power, and a cemented lens.

  With such a configuration, it is possible to satisfactorily correct spherical aberration while suppressing the occurrence of field curvature and coma.

  In the converter lens according to the present embodiment, it is desirable that the cemented lens has a negative lens and a positive lens in order from the object side. By using a cemented lens in the first lens unit having a negative refractive power, axial chromatic aberration can be favorably corrected.

In the converter lens according to the present embodiment, it is desirable that the lens group including the first and second lens groups satisfies the following conditions.
0.10 <D / M <0.60 (1)

  However, when the direction from the object side to the image side is a positive direction, D is the distance from the object side surface of the first lens to the mounting surface on the master lens side, and M is the mounting surface on the master lens side to the body side. It is the distance to the mounting surface.

  Conditional expression (1) is the distance from the object side surface of the first lens to the mounting surface on the master lens side, that is, the mounting surface of the converter lens with the master lens, and the mounting surface on the body side from the mounting surface on the master lens side. That is, it is a relational expression with the distance to the mounting surface of the converter lens with the camera body. When the conditional expression (1) is satisfied, the lens is arranged closer to the object side than the mounting surface on the master lens side as in the embodiments described later, thereby facilitating control of the exit pupil position and higher imaging performance. It is possible to realize a converter lens having the same.

  Below the lower limit of conditional expression (1), field curvature and coma are deteriorated, which is not desirable. If the lower limit of conditional expression (1) is set to 0.20, the effect of the present embodiment can be exhibited more significantly.

  If the upper limit value of conditional expression (1) is exceeded, the total length of the converter lens becomes large and cannot be attached to the master lens. Also, spherical aberration is deteriorated, which is not desirable. If the upper limit value of conditional expression (1) is set to 0.55, the effect of the present embodiment can be exhibited more significantly.

In the converter lens according to the present embodiment, it is desirable that the lens group including the first and second lens groups satisfies the following conditions.
−0.60 <β × TL / f1 <0.60 (2)

  Where β is the magnification of the converter lens, TL is the distance on the optical axis from the most object side lens surface to the most image side lens surface of the converter lens, and f1 is the first lens group. The focal length.

  Conditional expression (2) is a relational expression of the magnification of the converter lens, the total length of the converter lens, and the combined focal length of the first lens group. If the lower limit of conditional expression (2) is not reached, the negative refracting power of the first lens group will increase, making it difficult to correct spherical aberration and Petzval sum, which is not desirable. If the lower limit value of conditional expression (2) is set to -0.45, the effect of the present embodiment can be exhibited more significantly.

  If the upper limit of conditional expression (2) is exceeded, the positive refracting power of the first lens group will increase, making it difficult to correct curvature of field and coma, which is not desirable. If the upper limit value of conditional expression (2) is set to 0.45, the effect of the present embodiment can be exhibited more significantly.

In the converter lens according to the present embodiment, it is desirable that the cemented lens satisfies the following conditions.
0.75 <Np / Nn <0.95 (3)

  Where Np is the refractive index of the d-line (wavelength λ = 587.6 nm) of the positive lens of the cemented lens, and Nn is the refraction of the d-line (wavelength λ = 587.6 nm) of the negative lens of the cemented lens. Rate.

  Conditional expression (3) is a relational expression of the refractive index of the lens medium. If the lower limit value of conditional expression (3) is not reached, the cost increases because an expensive glass material is used. Further, the Petzval sum increases, and field curvature and coma are deteriorated. If the lower limit value of conditional expression (3) is set to 0.80, the effect of the present embodiment can be exhibited more significantly.

  If the upper limit of conditional expression (3) is exceeded, the Petzval sum will decrease, and field curvature and coma will deteriorate, which is undesirable. If the upper limit value of conditional expression (3) is set to 0.90, the effect of the present embodiment can be exhibited more remarkably.

Moreover, it is desirable that the converter lens according to the present embodiment satisfies the following conditions.
1.40 <β (4)

  Where β is the magnification of the converter lens.

  Conditional expression (4) defines the magnification at which the converter lens enlarges the focal length of the master lens in the infinitely focused state. If the lower limit value of conditional expression (4) is not reached, the magnification becomes insufficient and the lens does not function as a converter lens. If the lower limit value of conditional expression (4) is 1.50, the effect of the present embodiment can be exhibited more significantly.

  Further, the method for enlarging the focal length of the master lens according to the present embodiment includes, in order from the object side, a first lens group having negative refractive power and a second lens group having negative refractive power, The first lens group includes, in order from the object side, a converter lens having a first lens having a negative refractive power, a second lens having a positive refractive power, and a cemented lens of a negative lens and a positive lens. Achieved by mounting on the image side. With such a method, the focal length of the master lens can be easily increased.

(Example)
Hereinafter, examples of the converter lens according to the present embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a configuration in which a converter lens CL according to the first example of the present embodiment is attached to the master lens ML. In FIG. 1, the object side is on the left side and the image side is on the right side (the same applies to FIGS. 3 and 5).

  Converter lens CL is mounted on the image side of master lens ML. As shown in FIG. 1, the converter lens CL according to the first example includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a negative refractive power. Has been.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a concave surface facing the image plane I, a positive meniscus lens L2 having a convex surface facing the object side, a biconcave negative lens L3, and a biconvex lens. It is comprised from the cemented lens which consists of the shape positive lens L4.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens L5 having a concave surface facing the object side and a negative meniscus lens L6 having a concave surface facing the object side.

  The converter lens CL according to the first example has a configuration in which some lenses of the first lens group G1 are arranged on the object side of the master lens side mounting surface 10 which is a part to be mounted on the master lens ML. . With such a configuration, the exit pupil position can be easily controlled.

  Further, a body-side mounting surface 20 that is a part to be mounted on the camera body is formed at the end of the converter lens CL on the image plane I side.

  Table 1 below shows specification values of the master lens ML and the converter lens CL according to the first example.

  In (surface data) in the table, the object surface is the object surface, the surface number is the surface number from the object side, r is the radius of curvature, d is the surface spacing, and nd is the refraction at the d-line (wavelength λ = 587.6 nm). The ratio, νd represents the Abbe number in the d-line (wavelength λ = 587.6 nm), (stop) represents the aperture stop S, and the image plane represents the image plane I. Note that the refractive index nd in air is not shown. Further, “∞” in the radius of curvature r column indicates a plane.

  (Various data), f (ML) is the focal length of the master lens, FNO (ML) is the F number of the master lens, R is the shooting distance, f is the combined focal length when the converter lens is attached to the master lens, FNO Is the F number of the converter lens, 2ω is the angle of view of the converter lens (unit “°”), Y is the image height of the converter lens, TL is the total length of the converter lens, Bf is the back focus, f1 is the composite focus of the first lens group The distance D is the distance from the object-side surface of the first lens to the mounting surface on the master lens side, and M is the distance from the mounting surface on the master lens side to the mounting surface on the body side. The total length of the converter lens is a distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the converter lens.

  (Conditional expression corresponding value) indicates the corresponding value of each conditional expression.

  In all the following specification values, “mm” is generally used as the unit for the synthetic focal length f, curvature radius r, surface interval d and other lengths, etc. unless otherwise specified. The system is not limited to this because the same optical performance can be obtained even if the system is proportionally enlarged or reduced. Further, the unit is not limited to “mm”, and other appropriate units may be used. Furthermore, the description of these symbols is the same in the other examples below, and the description is omitted.

(Table 1)
[Surface data]
Surface number r d nd νd
Object ∞ ∞
1 ∞ 4.00 1.52238 64.10
2 ∞ 0.60
3 173.866 12.00 1.50201 82.51
4 -978.065 0.20
5 133.636 15.00 1.50201 82.51
6 -464.694 5.00 1.81620 46.54
7 332.918 46.30
8 99.554 3.50 1.75558 45.00
9 55.631 15.90 1.50201 82.51
10 -1371.060 29.55
11 -169.969 2.70 1.52238 64.10
12 67.285 4.51
13 -192.927 7.00 1.82062 33.89
14 -43.081 2.80 1.59583 61.09
15 83.887 19.21
16 (Aperture) ∞ 1.70
17 194.039 5.80 1.52373 69.98
18 -90.958 3.10
19 -43.595 3.50 1.81482 28.56
20 -64.790 7.60
21 -175.804 6.70 1.49227 70.40
22 -53.035 14.50
23 ∞ 3.63
24 ∞ 2.00 1.51680 64.10
25 ∞ 2.00
26 85.538 2.50 1.88300 40.76
27 28.264 1.00
28 31.267 6.00 1.60342 38.01
29 -251.100 10.59
30 -73.712 2.50 1.88300 40.76
31 46.806 10.00 1.62004 36.26
32 -39.478 10.77
33 -33.885 5.50 1.58913 61.16
34 -28.705 0.70
35 -65.514 3.00 1.88300 40.76
36 -415.209 113.61
Image plane ∞
[Various data]
f (ML) = 294.001
FNO (ML) = 2.89
R = infinity f = 583.6
FNO = 5.73
2ω = 4.24 °
Y = 2.69
TL = 52.6
Bf = 113.6
f1 = 832.7
D = 39.00
M = 80.66
[Values for each conditional expression]
Conditional expression (1) D / M = 0.48
Conditional expression (2) β × TL / f1 = 0.126
Conditional expression (3) Np / Nn = 0.860
Conditional expression (4) β = 2.0

  FIG. 2 shows various aberration diagrams of the converter lens CL according to the first example when focusing on infinity. In each aberration diagram, FNO represents an F number, Y represents an image height, and A represents a half angle of view (unit “°”). D shows the aberration curve of the d-line (wavelength λ = 587.6 nm), and G shows the aberration curve of the g-line (wavelength λ = 435.8 nm). In the spherical aberration diagram and the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image.

  As shown in each aberration diagram of FIG. 2, it can be seen that the converter lens according to Example 1 is well corrected for aberrations and has excellent imaging performance. FIG. 7 shows various aberrations during focusing at infinity when only the master lens ML is attached without the converter lens CL. In the following examples, the same symbols are used and the description thereof is omitted.

(Second embodiment)
FIG. 3 is a diagram showing a configuration in which the converter lens CL according to the second example of the present embodiment is attached to the master lens ML. As shown in FIG. 3, the converter lens CL according to the second example includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a negative refractive power. Has been.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a concave surface facing the image plane I, a positive meniscus lens L2 having a convex surface facing the object side, a biconcave negative lens L3, and a biconvex lens. It is comprised from the cemented lens which consists of the shape positive lens L4.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens L5 having a concave surface facing the object side and a negative meniscus lens L6 having a concave surface facing the object side.

  The converter lens CL according to the second example has a configuration in which some lenses of the first lens group G1 are disposed on the object side of the master lens side mounting surface 10 which is a part to be mounted on the master lens ML. . With such a configuration, the exit pupil position can be easily controlled.

  Further, a body-side mounting surface 20 that is a part to be mounted on the camera body is formed at the end of the converter lens CL on the image plane I side.

  Table 2 below shows specification values of the converter lens CL according to the second example.

(Table 2)
[Surface data]
Surface number r d nd νd
Object ∞ ∞
1 ∞ 4.00 1.51680 64.10
2 ∞ 0.60
3 173.866 12.00 1.49782 82.51
4 -978.065 0.20
5 133.636 15.00 1.49782 82.51
6 -464.694 5.00 1.80411 46.54
7 332.918 46.30
8 99.554 3.50 1.74400 45.00
9 55.631 15.90 1.49782 82.51
10 -1371.060 29.55
11 -169.969 2.70 1.51680 64.10
12 67.285 4.51
13 -192.927 7.00 1.80384 33.89
14 -43.081 2.80 1.58913 61.09
15 83.887 19.21
16 (Aperture) ∞ 1.70
17 194.039 5.80 1.51860 69.98
18 -90.958 3.10
19 -43.595 3.50 1.79504 28.56
20 -64.790 7.60
21 -175.804 6.70 1.48749 70.40
22 -53.035 14.50
23 ∞ 3.63
24 ∞ 2.00 1.51680 64.10
25 ∞ 12.00
26 96.736 2.50 1.882997 40.76
27 28.607 1.00
28 31.733 6.00 1.603420 38.01
29 -106.572 7.27
30 -46.665 2.50 1.882997 40.76
31 45.994 10.00 1.620041 36.26
32 -34.512 14.67
33 -39.919 5.50 1.589130 61.16
34 -29.336 0.70
35 -56.974 3.00 1.882997 40.76
36 -270.900 97.87
Image plane ∞
[Various data]
f (ML) = 294.001
FNO (ML) = 2.89
R = infinity f = 583.595
FNO = 5.71
2ω = 4.24 °
Y = 21.67
TL = 53.3
Bf = 97.7
f1 = −2186.1
D = 29.00
M = 75.50
[Values for each conditional expression]
Conditional expression (1) D / M = 0.38
Conditional expression (2) β × TL / f1 = −0.049
Conditional expression (3) Np / Nn = 0.860
Conditional expression (4) β = 2.0

  FIG. 4 shows various aberration diagrams of the converter lens CL according to Example 2 when focused on infinity.

  As shown in each aberration diagram of FIG. 4, it can be seen that the converter lens according to the second example is excellently corrected for aberrations and has excellent imaging performance.

(Third embodiment)
FIG. 5 is a diagram illustrating a configuration in which the converter lens CL according to the third example of the present embodiment is attached to the master lens ML. As shown in FIG. 5, the converter lens CL according to the third example includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a negative refractive power. Has been.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a concave surface facing the image plane I, a positive meniscus lens L2 having a convex surface facing the object side, a biconcave negative lens L3, and a biconvex lens. It is comprised from the cemented lens which consists of the shape positive lens L4.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens L5 having a concave surface facing the object side and a negative meniscus lens L6 having a concave surface facing the object side.

  The converter lens CL according to the third example has a configuration in which some lenses of the first lens group G1 are arranged on the object side of the master lens side mounting surface 10 which is a part to be mounted on the master lens ML. . With such a configuration, the exit pupil position can be easily controlled.

  Further, a body-side mounting surface 20 that is a part to be mounted on the camera body is formed at the end of the converter lens CL on the image plane I side.

  Table 3 below shows values of specifications of the converter lens CL according to the present example.

(Table 3)
[Surface data]
Surface number r d nd νd
Object ∞ ∞
1 ∞ 4.00 1.51680 64.10
2 ∞ 0.60
3 173.866 12.00 1.49782 82.51
4 -978.065 0.20
5 133.636 15.00 1.49782 82.51
6 -464.694 5.00 1.80411 46.54
7 332.918 46.30
8 99.554 3.50 1.74400 45.00
9 55.631 15.90 1.49782 82.51
10 -1371.060 29.55
11 -169.969 2.70 1.51680 64.10
12 67.285 4.51
13 -192.927 7.00 1.80384 33.89
14 -43.081 2.80 1.58913 61.09
15 83.887 19.21
16 (Aperture) ∞ 1.70
17 194.039 5.80 1.51860 69.98
18 -90.958 3.10
19 -43.595 3.50 1.79504 28.56
20 -64.790 7.60
21 -175.804 6.70 1.48749 70.40
22 -53.035 14.50
23 ∞ 3.63
24 ∞ 2.00 1.51680 64.10
25 ∞ 18.00
26 93.435 2.50 1.882997 40.76
27 27.969 1.00
28 31.317 6.00 1.603420 38.01
29 -96.618 7.27
30 -40.591 2.50 1.882997 40.76
31 38.572 10.00 1.620041 36.26
32 -30.590 14.67
33 -42.980 5.50 1.589130 61.16
34 -27.661 0.70
35 -45.340 3.00 1.882997 40.76
36 -184.597 86.71
Image plane ∞
[Various data]
f (ML) = 294.001
FNO (ML) = 2.89
R = infinity f = 583.600
FNO = 2.89
2ω = 4.24 °
Y = 21.70
TL = 53.1
Bf = 86.7
f1 = −1293.8
D = 23.00
M = 70.30
[Values for each conditional expression]
Conditional expression (1) D / M = 0.33
Conditional expression (2) β × TL / f1 = −0.082
Conditional expression (3) Np / Nn = 0.860
Conditional expression (4) β = 2.0

  FIG. 6 shows various aberration diagrams of the converter lens CL according to the third example when focusing on infinity.

  As shown in each aberration diagram of FIG. 6, it can be seen that the converter lens according to the third example is excellently corrected for aberrations and has excellent imaging performance.

  As shown in the above examples, according to the present embodiment, a converter lens having high imaging performance can be provided.

  Next, a camera equipped with the converter lens according to this embodiment will be described. In addition, although the case where the converter lens which concerns on 1st Example is mounted is demonstrated, it is the same also in another Example.

  FIG. 8 is a diagram illustrating a configuration of a camera including the converter lens according to the first example.

  In FIG. 8, a camera 30 is a digital single-lens reflex camera including a master lens ML as a photographing lens 32 and a converter lens CL according to the first embodiment attached to the master lens ML. In the camera 30, light from an unillustrated object (subject) is collected by the taking lens 32 and imaged on the collecting plate 34 via the quick return mirror 33. The light imaged on the collecting plate 34 is reflected a plurality of times in the pentaprism 35 and guided to the eyepiece lens 36. Thus, the photographer can observe the subject image as an erect image through the eyepiece lens 36.

  When the release button (not shown) is pressed by the photographer, the quick return mirror 33 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 37. As a result, light from the subject is picked up by the image sensor 37 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 30.

  By mounting the master lens ML as the photographing lens 32 on the camera 30 and the converter lens CL according to the first embodiment attached to the master lens ML, a camera having high performance can be realized.

  The contents described below can be appropriately adopted as long as the optical performance is not impaired.

  In the embodiment, the two-group configuration is shown, but the present invention can also be applied to a configuration in which another lens or lens group is added.

  Alternatively, the lens group or the partial lens group may be vibrated in a direction perpendicular to the optical axis so as to correct an image blur caused by camera shake.

  The lens surface may be an aspherical surface. In particular, when an aspherical lens is used as the cemented lens of the first lens group G1, the effect of correcting spherical aberration is remarkably improved. When using an aspheric lens, any aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface It doesn't matter.

  If each lens surface is provided with an antireflection film having high transmittance in a wide wavelength range, flare and ghost can be reduced and high contrast optical performance can be achieved.

  In this specification, in order to explain the present invention in an easy-to-understand manner, the configuration requirements of each embodiment have been described, but it goes without saying that the present invention is not limited to this.

It is sectional drawing which shows the structure of the converter lens which concerns on 1st Example. It is an aberration diagram at the time of focusing on infinity in the first example. It is sectional drawing which shows the structure of the converter lens which concerns on 2nd Example. It is an aberration diagram at the time of focusing on infinity in the second example. It is sectional drawing which shows the structure of the converter lens which concerns on 3rd Example. It is an aberration diagram at the time of focusing on infinity in the third example. It is an aberration diagram at the time of focusing on infinity of the master lens. It is a figure which shows the structure of the camera provided with the converter lens which concerns on 1st Example.

Explanation of symbols

CL converter lens ML master lens G1 first lens group L1 first lens L2 second lens SL cemented lens L3 negative lens L4 positive lens G2 second lens group L5 positive lens L6 negative lens I image plane S aperture stop 10 mounted on the master lens side Surface 20 Body side mounting surface 30 Camera

Claims (8)

A detachable converter lens used on the image side of the master lens ,
In order from the object side, a first lens having a negative refractive power, a second lens having a positive refractive power, a cemented lens, and a positive meniscus lens having a concave surface directed toward the object side, a negative meniscus with its concave surface facing the object side converter lens characterized by comprising a lens. The converter lens according to claim 1 , wherein the following condition is satisfied.
−0.60 <β × TL / f1 <0.60
However,
β: magnification of the converter lens TL: distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the converter lens f1: the first lens, the second lens, and the cemented lens Composite focal length Converter lens according to claim 1 or 2, characterized in that the following condition is satisfied.
1.40 <β
However,
β: magnification of the converter lens A detachable converter lens used on the image side of the master lens,
In order from the object side, the lens unit includes substantially two lens groups, a first lens group and a second lens group having negative refractive power.
It said first lens group comprises, in order from the object side, is a first lens having a negative refractive power, a second lens having a positive refractive power and a cemented lens, and satisfies the following condition Converter lens.
−0.45 <β × TL / f1 ≦ 0.126
1.40 <β
However,
β: magnification of the converter lens
TL: distance on the optical axis from the most object side lens surface to the most image side lens surface of the converter lens
f1: Focal length of the first lens group The cemented lens includes, in order from the object side, the converter lens according to claim 1, characterized in that it comprises a negative lens and a positive lens. The converter lens according to claim 1, wherein the following condition is satisfied.
0.10 <D / M <0.60
However, when the direction from the object side to the image side is a positive direction,
D: Distance from the object side surface of the first lens to the mounting surface on the master lens side
M: Distance from the mounting surface on the master lens side to the mounting surface on the body side The converter lens according to any one of claims 1 to 6 , wherein the cemented lens includes a negative lens and a positive lens, and the cemented lens satisfies the following condition.
0.75 <Np / Nn <0.95
However,
Np: refractive index of d-line of the positive lens of the cemented lens Nn: refractive index of d-line of the negative lens of the cemented lens An optical apparatus comprising the converter lens according to any one of 1 to 7 above.

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