JP2005043788A - Rear conversion lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear conversion lens whose performance is excellent and which has general applicability. <P>SOLUTION: The rear conversion lens RCL is connected between a master lens ML and a camera main body, and makes the focal distance of a total system long to the focal distance of the master lens ML. The part of a lens system has a first positive lens L113 having the refracting power of an absolute value stronger on an image side than an object side, a second negative lens L114 having the refracting power of an absolute value stronger on the image side than the object side, a third positive lens L115 having the refracting power of an absolute value stronger on the object side than the image side, a forth negative lens L116 having the refracting power of an absolute value stronger on the object side than the image side and fifth positive lens components L117 and L118 in order from the object side, and satisfies a conditional expression: Nd1>1.69 (then, Nd1 means the refractive index of the glass material of the first lens L113). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rear conversion lens that is attached to the image side of a master lens to increase the focal length, and more particularly to a rear conversion lens for a single-lens reflex camera.

Conventionally, rear conversion lenses for single-lens reflex cameras have been proposed. Such rear conversion lenses are disclosed in Patent Document 1, Patent Document 2, Patent Document 3, and the like. On the other hand, single-lens reflex cameras using electronic image sensors with a smaller screen size than conventional single-lens reflex cameras have begun to be used, and their performance is expected to be equal to or higher than conventional single-lens reflex camera films. Became. In particular, when the amount of light is secured, or when the depth of field is reduced and the bokeh is secured, a lens having a bright F value is required even with the same angle of view as that of a conventional single-lens reflex camera. In addition, an image is taken into a personal computer or the like, and a part of the screen is easily enlarged and used. Further, due to the necessity of a space such as a low-pass filter, a long back focus may be required for the screen size. Under such circumstances, higher performance with respect to the photographing lens is required, and further higher performance and versatility are required with respect to the rear conversion lens.
: JP-A-58-123515 : JP-A-60-260911 : JP-A-60-136712

  The present invention has been made in view of the above-mentioned problems of the prior art. The object is to provide a high performance and versatile rear conversion lens.

A rear conversion lens according to a first invention of the present application is a rear conversion lens that is connectable between a master lens and a camera body, and that increases the focal length of the entire system relative to the focal length of the master lens. In this order, from the object side, a positive first lens having a stronger absolute power on the image side than the object side and a negative second lens having a stronger absolute power on the image side than the object side A positive third lens having a refractive power that is stronger on the object side than the image side, a negative fourth lens having a stronger refractive power on the object side than the image side, and a positive fourth lens 5 lens components and satisfying the following conditional expression (1).
Nd1> 1.69 (1)
Nd1 is the refractive index of the glass material of the first lens.

The rear conversion lens of the second invention of the present application is characterized in that, in the rear conversion lens of the first invention, the following conditional expression (2) is further satisfied.
νd 1 <31 (2)
Here, νd 1 is the Abbe number of the glass material of the first lens.

The rear conversion lens of the third invention of the present application is characterized in that the rear conversion lens of the first or second invention further satisfies the following conditional expression (3).
-1.5 <Hb / Sd <-0.5 (3)
Where Hb is the rear principal point position of the rear conversion lens, and Sd is the distance from the object side surface of the first lens of the rear conversion lens to the image side surface of the image side lens.

  According to a fourth aspect of the present invention, there is provided a rear conversion lens according to any one of the first, second and third aspects of the invention, wherein the fifth lens component is a biconvex lens having a positive refractive power. And a negative meniscus lens having a convex surface facing the image side.

According to a fifth aspect of the present invention, in the rear conversion lens of the first, second, or third aspect, the fifth lens component satisfies the following conditional expression (4): It is characterized by only one biconvex positive refractive power lens of a low dispersion glass material.
νd 5> 60 (4)
νd 5 is the Abbe number of the glass material of the fifth lens.

  According to a sixth aspect of the present invention, there is provided a rear conversion lens according to any one of the first to fifth aspects of the invention, wherein a flare stop is formed between the first lens to the fifth lens component, or a flare is formed on the lens surface. It has a paint having a function as a diaphragm.

The rear conversion lens of the seventh invention of the present application is a state in which any of the rear conversion lenses of the first to sixth inventions forms an image on the imaging surface of the camera body when directly attached to the camera body. When the master lens is attached to the camera body via the rear conversion lens, the following conditional expression (5) is satisfied.
0.9 <IMM / IMG <1.02 (5)
Where IMM is the distance from the front surface of the first lens of the rear conversion lens to the master lens image plane position, and IMG is the distance from the final surface of the rear conversion lens to the image plane when the master lens is mounted.

According to an eighth aspect of the present invention, there is provided a rear conversion lens according to any one of the first to seventh aspects of the present invention, wherein the master lens is attached to the camera body via the rear conversion lens. Conditional expression (6) is satisfied.
Y / IMG <0.5 (6)
Y is the maximum image height on the imaging surface, and IMG is the distance from the final surface of the rear conversion lens to the image surface when the master lens is mounted.

The rear conversion lens of the ninth invention of the present application is characterized in that, in any of the conversion lenses of the first to eighth inventions, the first lens satisfies the following conditional expression (7).
-4.0 <(R2 + R1) / (R2-R1) <− 0.08 (7)
Where R1 is the radius of curvature of the object side surface of the first lens, and R2 is the radius of curvature of the image side surface of the first lens.

  According to the present invention, it is possible to increase the distance between the final surface of the rear conversion lens and the imaging surface while maintaining the performance of the optical system, and it is possible to provide a conversion lens having high versatility.

  Prior to the description of the embodiments of the present invention, actions and effects of the present invention will be described.

  The rear conversion lens according to the first invention of the present application includes, in order from the object side, a positive first lens having a refractive power with a stronger absolute value on the image side than on the object side, and a stronger absolute value on the image side than on the object side. A negative second lens having a refractive power, a positive third lens having a stronger absolute refractive power on the object side than the image side, and a negative having a stronger absolute refractive power on the object side than the image side By having the fourth lens and the positive fifth lens component, the layout is suitable for the rear conversion lens.

  According to the above configuration, it is easy to perform high-order spherical aberration correction with a plurality of lenses arranged on the master lens side located at a relatively high incident light height from the on-axis object point, while the image A plurality of lenses located on the side facilitates correction of off-axis aberrations. Further, as described above, when a use state such as a case where a long back focus is required with respect to the screen size is assumed, further correction of the axial aberration is required. Therefore, in the present invention, the conditional expression (1) is satisfied.

  Conditional expression (1) relates to the refractive index of the first lens. In the above configuration, when the conditional expression is satisfied, the curvature of the first lens can be relaxed, so that it is easy to suppress spherical aberration that occurs on the rear surface of the first lens. In particular, when a master lens with a bright F value is used to reduce the imaging area and to ensure the light quantity and blur, the axial light beam passing through the first lens is large and effective.

  According to the configuration of the second invention of the present application, by satisfying the conditional expression (2), it is possible to efficiently correct mainly on-axis chromatic aberration generated in the second lens or the fourth lens having a negative focal length. . Use of a high-dispersion glass material that satisfies conditional expression (2) for the positive first lens that has a wide on-axis luminous flux and a relatively low off-axis ray height in the rear conversion lens, thereby generating lateral chromatic aberration. This makes it easier to balance axial chromatic aberration while suppressing this.

  According to the configuration of the rear conversion lens of the third invention of the present application, it is easy to ensure the flatness of the image plane by satisfying conditional expression (3). When the upper limit of conditional expression (3) is exceeded, it becomes difficult to correct the negative Petzval sum generated in the rear conversion lens, and the tilt of the image plane tends to increase at the periphery. On the other hand, if the lower limit of conditional expression (3) is exceeded, the power of each lens component of the rear conversion lens tends to be strong, and the occurrence of aberrations on each surface increases, so that the optical performance is improved when the aperture of the master lens is large. It becomes difficult to secure.

  According to the configuration of the rear conversion lens of the fourth invention of the present application, it is advantageous to correct chromatic aberration, particularly lateral chromatic aberration, and coma aberration on the cemented surface. In addition, it is preferable to use a cemented lens so that the Petzval sum is more positive than the single lens, and the negative Petzval sum that is greatly generated in the second lens and the fourth lens can be corrected.

  According to the configuration of the rear conversion lens of the fifth invention of the present application, the lens component having a positive refractive power can be configured by a single positive lens in order to reduce the cost. In this case, in order to suppress as much as possible the lateral chromatic aberration generated by the lens component having a positive refractive power, it is preferable to use a glass material having a low dispersion that satisfies the conditional expression (5).

  According to the configuration of the rear conversion lens of the sixth invention of the present application, it is effective to prevent ghosts and flares generated on the optical surface, the edge of the lens, or the frame. For this purpose, it is desirable to form a frame having a flare stop function in the optical system, insert a flare stop sheet, or apply a coating having a flare stop function to the lens surface. Note that it is desirable that the opening of the flare stop be set to a shape that can effectively flare-cut at the image heights of the short side, the long side, and the diagonal by using a circle, a rectangle, or a combination thereof.

According to the configuration of the rear conversion lens of the seventh invention of the present application, it is possible to extend the distance from the final surface of the rear conversion lens to the image plane while maintaining the performance of the optical system, and versatility on the optical system. It becomes easy to enlarge. In the case of the configuration shown in Patent Document 3, it is difficult to extend the distance to the image plane while maintaining the performance. However, according to the configuration of the present invention, the distance to the image plane is set as described above. It can be extended, and versatility on the system can be improved.
However, if the upper limit of conditional expression (5) is exceeded, a long back focus is required for the master lens, and versatility for the master lens is reduced. On the other hand, if the lower limit of conditional expression (5) is exceeded, the power of the conversion lens tends to increase and aberrations tend to occur.

  According to the configuration of the rear conversion lens of the eighth invention of the present application, an optical system having high performance over the entire screen can be obtained. However, if Y / IMG is larger than 0.5, astigmatism and coma are likely to increase around the screen, and the optical performance tends to deteriorate. In addition, the decrease in the amount of peripheral light tends to increase.

  As described above, in the present invention, increasing the refractive index of the first lens group is advantageous for correcting the axial aberration. Further, in order to balance on-axis or off-axis aberration correction, it is more preferable that the lens shape satisfies the conditional expression (7) as in the rear conversion lens of the ninth invention of the present application. However, when the lower limit is exceeded, the refractive power of the image side surface of the first lens becomes strong, and axial aberrations are likely to occur. On the other hand, if the upper limit is exceeded, the angle at which the off-axis light beam is incident on the object side surface of the first lens becomes large, and off-axis aberration is likely to occur.

Furthermore, for each of the above conditional expressions, it is preferable to define an upper limit value and a lower limit value as follows.
For conditional expression (1), it is more preferable that the lower limit value be 1.75, and further 1.78. Moreover, it is preferable to set an upper limit value so as not to exceed 1.9. If the upper limit is exceeded, the lens material becomes expensive. Furthermore, it is more preferable not to exceed 1.85.

  For conditional expression (2), it is preferable to set a lower limit value so as not to exceed 23. If the lower limit is exceeded, the lens material becomes expensive. Furthermore, it is more preferable not to exceed 23.5. Further, it is more preferable that the upper limit value is 29, further 27.

  For conditional expression (3), it is more preferable that the lower limit value be −1.4, and further −1.2. Further, it is more preferable that the upper limit value is −0.7, and further −0.8.

  For conditional expression (4), it is more preferable to set the lower limit to 65, or even 70. Also, it is preferable to set an upper limit value so that it does not exceed 85. If the upper limit is exceeded, the lens material becomes expensive. Furthermore, it is more preferable not to exceed 75.

  For conditional expression (5), it is more preferable that the lower limit value be 0.93, more preferably 0.95. Further, it is more preferable that the upper limit value is 1.01, and further 1.00.

  For conditional expression (6), it is preferable to set a lower limit value so as not to exceed 0.1. If the lower limit is exceeded, the lens system tends to be complicated for correcting spherical aberration. Furthermore, it is more preferable not to exceed 0.2. Further, it is more preferable that the upper limit value is 0.45, further 0.4.

  For conditional expression (7), it is more preferable that the lower limit value be −3.0, and further −2.5. Further, it is more preferable that the upper limit value is −0.2, further −0.28, and −0.4.

Here, first, the configuration of an optical system that combines the rear conversion lens of the present invention and its master lens will be described.
FIG. 1 is a cross-sectional view along the optical axis showing the configuration of an optical system combining a rear conversion lens lens and a master lens according to the present invention.
As shown in FIG. 1, the master lens ML includes a first lens group G1, a second lens group G2, a third lens group G3, a diaphragm S, and a fourth lens group G4 in order from the object side. is doing. The first lens group G1, in order from the object side, has a negative refractive power lens L1 with a convex surface facing the object side, a positive lens L2 with both convex surfaces, a positive refractive power lens L3 with a convex surface facing the object side, It is composed of a lens L4 having a negative refractive power with the concave surface facing the object side, and has a positive refractive power as a whole. The second lens group G2, in order from the object side, has a positive refractive power lens L5 with a concave surface facing the object side, a negative refractive power lens L6 with a concave surface facing the object side, and negative refractive powers of both concave surfaces. The lens L7 has a negative refractive power as a whole. The lenses L5 and L6 are cemented. The third lens group G3 includes a lens L8 having a negative refractive power with a convex surface facing the object side, and a positive lens L9 having a biconvex surface, and has a positive refractive power as a whole. The fourth lens group G4 includes a negative refractive power lens L10 having a concave surface facing the object side, a positive lens L11 having a convex surface facing the object side, and a negative refractive power lens L12 having a convex surface facing the object side. Has been. The lenses L10 and L11 are cemented. The aperture stop S is provided between the lens L9 of the third lens group G3 and the lens L10 of the fourth lens group G4.

  A rear conversion lens RCL is disposed between the master lens ML and the imaging surface P. FIG. 1 shows an example in which the rear conversion lens RCL is composed of six lenses L113 to L118.

Next, a master lens used in combination with the rear conversion lens according to the present invention will be described.
FIG. 2 is a cross-sectional view taken along the optical axis of the optical configuration of the master lens used in combination with the rear conversion lens of each embodiment of the present invention. FIG. 16 shows the spherical aberration (DZY), astigmatism (FC), distortion (DTL) and lateral chromatic aberration (CC) of the master lens. The symbols DZY, FC, DTL, and CC are used in the same meaning in each of FIGS.

Numerical data of optical members constituting the optical system of the master lens is shown below.
In the master lens numerical data, r ₁ , r ₂ ,... Are the curvature radii of the lens surfaces, d ₁ , d ₂ ,... Are the thickness or air spacing of the lenses, and n _d1 , n _d2,. , D _d , ν _d2 ,... Are Abbe numbers of the respective lenses, Fno. Represents the F number, and f represents the total focal length.
These symbols are also used in common in the numerical data of Examples 1 to 11 relating to the rear conversion lens of the present invention described later.

Numerical data 1
(Master lens : Fig. 2 )
Example value f = 300mm Fno = 2.8 Half angle of view ω = 2.3 °
r ₁ = 248.8583
d ₁ = 6.2258 n _d1 = 1.74950 ν _d1 = 35.28
r ₂ = 149.7739
d ₂ = 2.1820
r ₃ = 133.6304
d ₃ = 1.49700 n _d3 = 18.5000 ν _d3 = 81.54
r ₄ = −317.0995
d ₄ = 0.5859
r ₅ = 130.9539
d ₅ = 14.4960 n _d5 = 1.49700 ν _d5 = 81.54
r ₆ = 938.4581
d ₆ = 7.4719
r ₇ = −399.8887
d ₇ = 6.0000 n _d7 = 1.83400 ν _d7 = 37.16
r ₈ = −5911.8564
d ₈ = 52.2724
r ₉ = −1176.4309
d ₉ = 9.5252 n _d9 = 1.84666 ν _d9 = 23.78
r ₁₀ = −139.4432
d ₁₀ = 3.5880 n _d10 = 1.63930 ν _d10 = 44.87
r ₁₁ = −8552.4362
d ₁₁ = 1.2541
r ₁₂ = −1073.3817
d ₁₂ = 3.4426 n _d12 = 1.69680 ν _d12 = 55.53
r ₁₃ = 93.0994
d ₁₃ = 36.8207
r ₁₄ = 86.4715
d ₁₄ = 3.5687 n _d14 = 1.80100 ν _d14 = 34.97
r ₁₅ = 57.0560
d ₁₅ = 1.6186
r ₁₆ = 58.0496
d ₁₆ = 12.1657 n _d16 = 1.49700 ν _d16 = 81.54
r ₁₇ = −190.3950
d ₁₇ = 5.220
r ₁₈ = ∞ (aperture)
d ₁₈ = 12.0000
r ₁₉ = −719.5271
d ₁₉ = 4.5680 n _d19 = 1.56732 ν _d19 = 42.82
r ₂₀ = 52.1479
d ₂₀ = 10.0933 n _d20 = 1.80610 ν _d20 = 40.92
r ₂₁ = 529.2439
d ₂₁ = 0.5526
r ₂₂ = 68.1373
d ₂₂ = 6.3521 n _d22 = 1.69680 ν _d22 = 55.53
r ₂₃ = 42.0858
d ₂₃ = 96.4947
P = Imaging surface

  Example 1 of a rear conversion lens according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view along an optical axis showing an optical configuration in which a master lens and a rear conversion lens according to the present invention are combined. FIG. 3 is a cross-sectional view along the optical axis showing the optical configuration of the rear conversion lens according to the first embodiment. FIG. 14 is a diagram seen from the light incident side of the rear conversion lens in each embodiment. FIG. 15 is a schematic view of the entire camera when the master lens and the rear conversion lens according to the present invention are applied to a single-lens reflex camera. FIG. 17 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens attached) according to Example 1.

  As shown in FIG. 3, the rear conversion lens of Example 1 is composed of six lenses. In order from the object side, a first lens L113 having a positive refractive power having a convex surface on the object side, a second lens L114 having a negative refractive power having a convex surface on the object side, and a third lens having a positive refractive power having a convex surface on the object side. The lens L115 includes a fourth lens L116 having a negative refractive power having a concave surface on the object side, a lens L117 having a positive refractive power on both convex surfaces, and a lens L118 having a negative refractive power having a concave surface on the object side. The positive power lens L117 and the negative power lens L118 are cemented. In this example, the fifth lens component is a cemented lens of the lens L117 and the lens L118 having a negative refractive power. In FIG. 4, P is an imaging surface.

Next, the configuration of the conversion lens RCL holder, the flare stop, and the like will be described with reference to the drawings. FIG. 14 is a view of the rear conversion lens in the first embodiment as viewed from the light incident side. FIG. 15 is a schematic sectional view of a single-lens reflex camera using the rear conversion lens and the master lens of the present invention.
In FIG. 14, the main body 4 of the conversion lens RCL has a bayonet type mount 3 on the master lens ML side and a mount 2 on the camera main body. (Refer to 2, 3, and 4 in FIG. 15) Further, the electrical contact 13 for electrically connecting the master lens ML and the camera body to transmit signals such as aperture adjustment, focal length, and in-focus state. 16 is arranged in front of and behind the rear conversion lens body. (Refer to 13 and 16 in FIG. 15) Between the contacts 13 and 16, the F number information and the like are corrected to prevent a malfunction between the camera body and the master lens, etc. (in FIG. 15) 15) is provided in the conversion lens body 4.

  In Example 1, when viewed from the incident side of the rear conversion lens, the field stop S2 in which the image side surface of the second lens L114 is coated with a circular black paint, the second lens L114, and the third lens L115. Is arranged so that a substantially rectangular flare stop S3 provided between the two can be seen. Furthermore, a circular field stop is provided integrally with the lens holding frame on the incident surface side of the third lens L115, and a ring-shaped field stop S4 (shown by a broken line in FIG. 14) between the fourth lens L116 and the fifth lens L117. (Shown).

  In Examples 1 to 8, the rear conversion lens is composed of six lenses, and the fifth lens of these Examples is joined with a diameter smaller than that of the sixth lens. Is abutted against and supported. Also, the peripheral surface of each lens is painted black to reduce the occurrence of flare. The configurations of the conversion lens holder, the flare stop, and the like described above are the same for the second to eleventh embodiments.

  In the first embodiment, the fifth lens L117 has a diameter smaller than that of the sixth lens L118 and is joined. The sixth lens has a diameter of six lenses. The same applies to the other Examples 2 to 8. As will be described later, in Examples 9 to 11, the conversion lens is composed of five lenses.

Nd1, ν _d1 , ν _d5 , R1 and R2 in the above conditional expressions respectively correspond to n _d24 , ν _d24 , ν _d32 , r ₂₄ and r ₂₅ in the numerical data 2 of the first embodiment shown below.
These relationships are the same in the second to eleventh embodiments.

Next, numerical data of optical members constituting the master lens and the rear conversion lens optical system in Example 1 are shown.
The numerical data of the master lens is represented by r ₁ to r ₂₃ , d ₁ to d ₂₃ , n _d1 to n _d23 , and ν _d1 to ν _d23 . Numerical data with the rear conversion lens is represented by r ₂₄ to r ₃₄ , d ₂₄ to d ₃₄ , n _d24 to n _d33 , and ν _d24 to ν _d33 .

Numerical data 2:
( Example 1: FIG. 3) Numerical data of rear conversion lens Master lens: f = 300 mm Fno = 2.8 Half angle of view 2ω = 2.3 °
Rear conversion lens: f = 431.24mm Fno = 4.0
Magnification = 1.44
r ₁ = 248.8583
d ₁ = 6.2258 n _d1 = 1.74950 ν _d1 = 35.28
r ₂ = 149.7739
d ₂ = 2.1820
r ₃ = 133.6304
d ₃ = 1.49700 n _d3 = 18.5000 ν _d3 = 81.54
r ₄ = −317.0995
d ₄ = 0.5859
r ₅ = 130.9539
d ₅ = 14.4960 n _d5 = 1.49700 ν _d5 = 81.54
r ₆ = 938.4581
d ₆ = 7.4719
r ₇ = −399.8887
d ₇ = 6.0000 n _d7 = 1.83400 ν _d7 = 37.16
r ₈ = −5911.8564
d ₈ = 52.2724
r ₉ = −1176.4309
d ₉ = 9.5252 n _d9 = 1.84666 ν _d9 = 23.78
r ₁₀ = −139.4432
d ₁₀ = 3.5880 n _d10 = 1.63930 ν _d10 = 44.87
r ₁₁ = −8552.4362
d ₁₁ = 1.2541
r ₁₂ = −1073.3817
d ₁₂ = 3.4426 n _d12 = 1.69680 ν _d12 = 55.53
r ₁₃ = 93.0994
d ₁₃ = 36.8207
r ₁₄ = 86.4715
d ₁₄ = 3.5687 n _d14 = 1.80100 ν _d14 = 34.97
r ₁₅ = 57.0560
d ₁₅ = 1.6186
r ₁₆ = 58.0496
d ₁₆ = 12.1657 n _d16 = 1.49700 ν _d16 = 81.54
r ₁₇ = −190.3950
d ₁₇ = 5.220
r ₁₈ = ∞ (aperture)
d ₁₈ = 12.0000
r ₁₉ = −719.5271
d ₁₉ = 4.5680 n _d19 = 1.56732 ν _d19 = 42.82
r ₂₀ = 52.1479
d ₂₀ = 10.0933 n _d20 = 1.80610 ν _d20 = 40.92
r ₂₁ = 529.2439
d ₂₁ = 0.5526
r ₂₂ = 68.1373
d ₂₂ = 6.3521 n _d22 = 1.69680 ν _d22 = 55.53
r ₂₃ = 42.0858
d ₂₃ = 63.4432
r ₂₄ = 359.8030
d ₂₄ = 2.5129 n _d24 = 1.84666 ν _d24 = 23.78
r ₂₅ = −73.3836
d ₂₅ = 0.1000
r ₂₆ = 282.5745
d ₂₆ = 1.3000 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 19.6533
d ₂₇ = 1.4100
r ₂₈ = 27.5315
d ₂₈ = 2.3918 n _d28 = 1.68893 ν _d28 = 31.07
r ₂₉ = 52.6405
d ₂₉ = 3.6661
r ₃₀ = −26.1156
d ₃₀ = 1.3000 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = −92.4209
d ₃₁ = 0.2000
r ₃₂ = 29.5485
d ₃₂ = 6.8435 n _d32 = 1.57501 ν _d32 = 41.50
r ₃₃ = −19.9659
d ₃₃ = 1.4000 n _d33 = 1.84666 ν _d33 = 23.78
r ₃₄ = −45.8151
d ₃₄ = 33.7653
P = Imaging surface

The numerical values Nd1 (n _d24 ), _νd1 (ν _d24 ), Hb, Sd, Y, IMM, IMG, R1 (r ₂₄ ), and R2 (r ₂₅ ) in Example 1 are shown in Table 1. Yes. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

Embodiment 2 of the rear conversion lens according to the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view along the optical axis showing the optical configuration of the rear conversion lens according to the second embodiment. FIG. 4 is a cross-sectional view along the optical axis showing an optical configuration according to Example 2 of the zoom lens used in the rear conversion lens according to the present invention. FIG. 18 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens attached) according to Example 2.
As shown in FIG. 4, the rear conversion lens of Example 2 is composed of six lenses. In order from the object side, a first lens L213 having a positive refractive power having a concave surface on the object side, a second lens L214 having a negative refractive power having a convex surface on the object side, and a positive refractive power having a convex surface on the object side. The lens includes a third lens L215, a fourth lens L216 having a negative refractive power having a concave surface on the object side, a lens L217 having a positive refractive power on both convex surfaces, and a lens L218 having a negative refractive power having a concave surface on the object side. Is done. The positive refractive power lens L217 and the negative refractive power lens L218 are cemented. In this example, the fifth lens component is a cemented lens of a lens L217 and a lens L218 having a negative refractive power. Note that the configuration of the conversion lens holder, the flare stop, and the like are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 2 are shown. The numerical data of the master lens combined with the rear conversion lens is the same as the numerical data 1 shown in the first embodiment, and will be omitted.

Numerical data 3
( Example 2: FIG. 4)
f = 417.99mm Fno = 3.9 Magnification = 1.39
r ₂₄ = −132.9464
d ₂₄ = 2.2620 n _d24 = 1.84666 ν _d24 = 23.78
r ₂₅ = −47.4861
d ₂₅ = 0.1000
r ₂₆ = 979.5421
d ₂₆ = 1.3000 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 21.6641
d ₂₇ = 0.9492
r ₂₈ = 27.3416
d ₂₈ = 3.0160 n _d28 = 1.68893 ν _d28 = 31.07
r ₂₉ = 231.5979
d ₂₉ = 2.5486
r ₃₀ = −33.1511
d ₃₀ = 1.3000 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = 128.8271
d ₃₁ = 0.2000
r ₃₂ = 29.5910
d ₃₂ = 6.1914 n _d32 = 1.57501 ν _d32 = 41.50
r ₃₃ = −18.9460
d ₃₃ = 1.4000 n _d33 = 1.84666 ν _d33 = 23.78
r ₃₄ = −44.9111
d ₃₄ = 33.1853
P = Imaging surface

The numerical values Nd1 (n _d24 ), _νd1 (ν _d24 ), Hb, Sd, Y, IMM, IMG, R1 (r ₂₄ ), and R2 (r ₂₅ ) in Example 2 are shown in Table 1. Yes. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 5 is a sectional view taken along the optical axis of the optical configuration of the rear conversion lens according to the third embodiment of the present invention. FIG. 19 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) according to Example 3.
The rear conversion lens of Example 3 is composed of six lenses as shown in FIG. In order from the object side, a first lens L313 having a positive refractive power having a concave surface on the object side, a second lens L314 having a negative refractive power having a concave surface on the object side, a third lens L315 having a positive refractive power on both convex surfaces, The lens includes a fourth lens L316 having a negative refractive power having a concave surface on the object side, a lens L317 having a positive refractive power on both convex surfaces, and a lens L318 having a negative refractive power having a concave surface on the object side. The lens L317 having a positive refractive power and the lens L318 having a negative refractive power are cemented. In this example, the fifth lens component is a cemented lens of a lens L317 and a lens L318 having a negative refractive power. Note that the configuration of the conversion lens holder, the flare stop, and the like are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 3 are shown. Since the data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 4
( Example 3: FIG. 5)
f = 433.19mm Fno = 4.0 Magnification = 1.44
r ₂₄ = −1641.2916
d ₂₄ = 2.5000 n _d24 = 1.84666 ν _d24 = 23.78
r ₂₅ = −56.3563
d ₂₅ = 0.1000
r ₂₆ = −116.8605
d ₂₆ = 1.3000 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 20.1636
d ₂₇ = 0.8483
r ₂₈ = 23.9016
d ₂₈ = 4.7501 n _d28 = 1.58144 ν _d28 = 40.75
r ₂₉ = −42.1870
d ₂₉ = 1.1852
r ₃₀ = −35.7184
d ₃₀ = 1.3000 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = 74.5061
d ₃₁ = 0.2000
r ₃₂ = 25.2699
d ₃₂ = 5.5535 n _d32 = 1.56732 ν _d32 = 42.82
r ₃₃ = −44.4041
d ₃₃ = 1.4000 n _d33 = 1.84666 ν _d33 = 23.78
r ₃₄ = −3584.9185
d ₃₄ = 33.5001
P = Imaging surface

The numerical values Nd1 (n _d24 ), _νd1 (ν _d24 ), Hb, Sd, Y, IMM, IMG, R1 (r ₂₄ ), and R2 (r ₂₅ ) in Example 3 are shown in Table 1. Yes. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

  FIG. 6 is a sectional view taken along the optical axis of the optical configuration of the rear conversion lens according to Example 4 of the present invention. FIG. 20 shows spherical aberration, astigmatism, distortion aberration, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) according to Example 4.

  As shown in FIG. 6, the rear conversion lens of Example 4 is composed of six lenses. In order from the object side, a lens L413 having a positive refractive power having a concave surface on the object side, a lens L414 having a negative refractive power having a convex surface on the object side, a lens L415 having a positive refractive power on the image side, and a concave surface on the object side Lens L416 having negative refractive power, lens L417 having positive refractive power of both convex surfaces, and lens L418 having negative refractive power having a concave surface on the object side. The positive refractive power lens L417 and the negative refractive power lens L418 are cemented. In this example, the fifth lens component is a cemented lens of a lens L417 and a lens L418 having a negative refractive power. Note that the configuration of the conversion lens holder, the flare stop, and the like are the same as in the case of the first embodiment, and a description thereof will be omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 4 are shown. Since the numerical data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 5
( Example 4: FIG. 6 )
f = 424.22mm Fno = 4.0 Magnification = 1.41
r ₂₄ = −129.0313
d ₂₄ = 2.0106 n _d24 = 1.83400 ν _d24 = 37.16
r ₂₅ = −42.8247
d ₂₅ = 0.1061
r ₂₆ = 2019.6728
d ₂₆ = 1.2875 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 17.8843
d ₂₇ = 0.5191
r ₂₈ = 19.7507
d ₂₈ = 3.5941 n _d28 = 1.69895 ν _d28 = 30.13
r ₂₉ = 133.4047
d ₂₉ = 3.0606
r ₃₀ = −25.3383
d ₃₀ = 0.9595 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = 393.4842
d ₃₁ = 0.1762
r ₃₂ = 32.1869
d ₃₂ = 6.5091 n _d32 = 1.49700 ν _d32 = 81.54
r ₃₃ = −18.8529
d ₃₃ = 1.1987 n _d33 = 1.80400 ν _d33 = 46.57
r ₃₄ = −31.1623
d ₃₄ = 33.2019
P = Imaging surface

The numerical values, Nd1 (n _d24 ), _νd1 (ν _d24 ), Hb, Sd, Y, IMM, IMG, R1 (r ₂₄ ), R2 (r ₂₅ ) in Example 4 are shown in Table 1. ing. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 7 is a cross-sectional view along the optical axis showing the optical configuration of the rear conversion lens according to Example 5 of the present invention. FIG. 21 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens mounted) according to Example 5.
As shown in FIG. 7, the rear conversion lens of Example 5 is composed of six lenses. In order from the object side, a lens L513 having a positive refractive power having a convex surface on the object side, a lens L514 having a negative refractive power having a convex surface on the object side, a lens L515 having a positive refractive power on the image side, and a concave surface on the object side Negative refractive power lens L516 having a positive refractive power, biconvex positive lens L517, and negative refractive power lens L518 having a concave surface on the object side. The lens L517 having a positive refractive power and the lens L518 having a negative refractive power are cemented. In this example, the fifth lens component is a cemented lens of a lens L517 and a lens L518 having a negative refractive power. Note that the configuration of the conversion lens holder, the flare stop, and the like are the same as in the case of the first embodiment, and a description thereof will be omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 5 are shown. Since the numerical data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 6
( Example 5: FIG. 7 )
f = 418.00mm Fno = 3.9 Magnification = 1.39
r ₂₄ = 286.6108
d ₂₄ = 2.0684 n _d24 = 1.80518 ν _d24 = 25.42
r ₂₅ = −76.5047
d ₂₅ = 0.1000
r ₂₆ = 131.7207
d ₂₆ = 1.3000 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 18.7693
d ₂₇ = 1.0040
r ₂₈ = 24.0261
d ₂₈ = 2.1682 n _d28 = 1.67270 ν _d28 = 32.10
r ₂₉ = 46.3397
d ₂₉ = 3.6202
r ₃₀ = −25.3063
d ₃₀ = 1.000 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = −119.1134
d ₃₁ = 0.2000
r ₃₂ = 31.0606
d ₃₂ = 6.5220 n _d32 = 1.56732 ν _d32 = 42.82
r ₃₃ = −19.2274
d ₃₃ = 1.0000 n _d33 = 1.80518 ν _d33 = 25.42
r ₃₄ = −41.3671
d ₃₄ = 33.0058
P = Imaging surface

Specifications of numerical values in Example _{5, Nd1 (n d24),} νd1 (ν d24), Hb, Sd, Y, IMM, IMG, R1 (r 24), the R2 (r ₂₅₎ are shown in Table 1 ing. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 8 is a cross-sectional view along the optical axis showing the optical configuration of the rear conversion lens according to Example 6 of the present invention. FIG. 22 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens attached) according to Example 6.
As shown in FIG. 8, the rear conversion lens of Example 6 is composed of six lenses. In order from the object side, a lens L613 having a positive refractive power having a convex surface on the object side, a lens L614 having a negative refractive power having a convex surface on the object side, a lens L615 having a positive refractive power on the image side, and a concave surface on the object side. Lens L616 having negative refractive power, lens L617 having positive refractive power of both convex surfaces, and lens L618 having negative refractive power having concave surface on the object side. The positive refractive power lens L617 and the negative refractive power lens L618 are cemented. In this example, the fifth lens component is a cemented lens of a lens L617 and a lens L618 having a negative refractive power. Note that the configuration of the conversion lens holder, the flare stop, and the like are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 6 are shown. Since the numerical data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 7
(Example 6: FIG. 8)
f = 418.86mm Fno = 3.9 Magnification = 1.40
r ₂₄ = 1.082 × 10 ⁴
d ₂₄ = 2.0000 n _d24 = 1.84666 ν _d24 = 23.78
r ₂₅ = −77.5313
d ₂₅ = 0.1000
r ₂₆ = 149.8247
d ₂₆ = 1.3000 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 20.9514
d ₂₇ = 1.3552
r ₂₈ = 33.9962
d ₂₈ = 2.0000 n _d28 = 1.72825 ν _d28 = 28.46
r ₂₉ = 93.2600
d ₂₉ = 2.3718
r ₃₀ = −39.1365
d ₃₀ = 1.000 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = −2193.8266
d ₃₁ = 0.2000
r ₃₂ = 26.7483
d ₃₂ = 6.4465 n _d32 = 1.57501 ν _d32 = 41.50
r ₃₃ = −23.1275
d ₃₃ = 1.3000 n _d33 = 1.78470 ν _d33 = 26.29
r ₃₄ = −121.8987
d ₃₄ = 32.9965
P = Imaging surface

The numerical values, Nd1 (n _d24 ), _νd1 (ν _d24 ), Hb, Sd, Y, IMM, IMG, R1 (r ₂₄ ), and R2 (r ₂₅ ) in Example 6 are shown in Table 1. ing. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 9 is a sectional view taken along the optical axis of the optical configuration of the rear conversion lens according to Example 7 of the present invention. FIG. 23 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) according to Example 7.
As shown in FIG. 9, the rear conversion lens of Example 7 is composed of six lenses. In order from the object side, a lens L713 having a positive refractive power having a convex surface on the object side, a lens L714 having a negative refractive power having a convex surface on the object side, a lens L715 having a positive refractive power on the image side, and a concave surface on the object side. A negative refractive power lens L716 having a positive refractive power, a birefringent positive refractive power lens L717, and a negative refractive power lens L718 having a concave surface on the object side. The lens L717 having a positive refractive power and the lens L718 having a negative refractive power are cemented. In this example, the fifth lens component is a cemented lens of a lens L717 and a lens L718 having a negative refractive power. Note that the configuration of the conversion lens holder, the flare stop, and the like are the same as in the case of the first embodiment, and a description thereof will be omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 7 are shown. Since the numerical data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 8
( Example 7: FIG. 9 )
f = 422.08mm Fno = 3.9 Magnification = 1.41
r ₂₄ = 4.838 × 10 ⁴
d ₂₄ = 2.0000 n _d24 = 1.80518 ν _d24 = 25.42
r ₂₅ = −61.3805
d ₂₅ = 0.1000
r ₂₆ = 145.5802
d ₂₆ = 1.2096 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 18.2264
d ₂₇ = 0.6478
r ₂₈ = 20.0900
d ₂₈ = 2.7052 n _d28 = 1.62588 ν _d28 = 35.70
r ₂₉ = 49.0713
d ₂₉ = 4.3714
r ₃₀ = −21.1714
d ₃₀ = 1.000 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = −105.9732
d ₃₁ = 0.2000
r ₃₂ = 41.3989
d ₃₂ = 6.9089 n _d32 = 1.54814 ν _d32 = 45.79
r ₃₃ = −17.0907
d ₃₃ = 1.0987 n _d33 = 1.80518 ν _d33 = 25.42
r ₃₄ = -27.6461
d ₃₄ = 32.9979
P = Imaging surface

The numerical values, Nd1 (n _d24 ), _νd1 (ν _d24 ), Hb, Sd, Y, IMM, IMG, R1 (r ₂₄ ), and R2 (r ₂₅ ) in Example 7 are shown in Table 1. ing. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 10 is a cross-sectional view along the optical axis of the optical configuration of the rear conversion lens according to Example 8 of the present invention. FIG. 24 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens attached) according to Example 8.
As shown in FIG. 10, the rear conversion lens of Example 8 is composed of six lenses. In order from the object side, a lens L813 having a positive refractive power having a convex surface on the object side, a lens L814 having a negative refractive power having a convex surface on the object side, a lens L815 having a positive refractive power on the image side, and a concave surface on the object side A negative refractive power lens L816 having a positive refractive power, a birefringent positive refractive power lens L817, and a negative refractive power lens L818 having a concave surface on the object side. The positive refractive power lens L817 and the negative refractive power lens L818 are cemented. In this example, the fifth lens component is a cemented lens of the lens L817 and the lens L818. Note that the configuration of the conversion lens holder, the flare stop, and the like are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 8 are shown. Since the numerical data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 9
( Example 8: FIG. 10 )
f = 423.14mm Fno = 3.9 Magnification = 1.41
r ₂₄ = 2396.1854
d ₂₄ = 2.0000 n _d24 = 1.84666 ν _d24 = 23.78
r ₂₅ = −85.7601
d ₂₅ = 0.1000
r ₂₆ = 173.1504
d ₂₆ = 1.3000 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 19.7723
d ₂₇ = 1.5842
r ₂₈ = 31.1148
d ₂₈ = 1.8662 n _d28 = 1.72151 ν _d28 = 29.23
r ₂₉ = 76.4686
d ₂₉ = 2.3686
r ₃₀ = -41.5661
d ₃₀ = 1.000 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = −1180.9667
d ₃₁ = 0.2000
r ₃₂ = 26.8201
d ₃₂ = 6.1487 n _d32 = 1.57501 ν _d32 = 41.50
r ₃₃ = −24.7871
d ₃₃ = 0.9586 n _d33 = 1.78472 ν _d33 = 25.68
r ₃₄ = −92.7890
d ₃₄ = 35.0102
P = Imaging surface

The numerical values, Nd1 (n _d24 ), _νd1 (ν _d24 ), Hb, Sd, Y, IMM, IMG, R1 (r ₂₄ ), and R2 (r ₂₅ ) in Example 8 are shown in Table 1. ing. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 11 is a sectional view taken along the optical axis of the optical configuration of the rear conversion lens according to Example 9 of the present invention. FIG. 25 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens attached) according to Example 9.
As shown in FIG. 11, the rear conversion lens of Example 9 is composed of five lenses. In order from the object side, a first lens L913 having a positive refractive power having a convex surface on the object side, a second lens L914 having a negative refractive power having a convex surface on the object side, and a third lens having a positive refractive power having a convex surface on the image side. L915, a fourth lens L916 having a negative refractive power having a concave surface on the object side, and a fifth lens L917 having a positive refractive power of both convex surfaces. In this example, the fifth lens component is the lens L917. The configurations of the conversion lens holder, the flare stop, and the like are the same as those described in the first embodiment, and are therefore omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 9 are shown. Since the numerical data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 10
( Example 9: FIG. 11 )
f = 418.17mm Fno = 3.9 Magnification = 1.39
r ₂₄ = 135.0795
d ₂₄ = 2.0080 n _d24 = 1.72825 ν _d24 = 28.46
r ₂₅ = −102.3335
d ₂₅ = 0.1000
r ₂₆ = 150.7993
d ₂₆ = 1.2863 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 17.2206
d ₂₇ = 0.6863
r ₂₈ = 19.6072
d ₂₈ = 3.4177 n _d28 = 1.59551 ν _d28 = 39.24
r ₂₉ = 74.2265
d ₂₉ = 3.1638
r ₃₀ = −32.3545
d ₃₀ = 1.1903 n _d30 = 1.80400 ν _d30 = 46.57
r ₃₁ = 298.3005
d ₃₁ = 0.1000
r ₃₂ = 30.4788
d ₃₂ = 4.5808 n _d32 = 1.48749 ν _d32 = 70.23
r ₃₃ = −62.4700
d ₃₃ = 32.9995
P = Imaging surface

Specifications of numerical values in Example _{9, Nd1 (n d24),} νd1 (ν d24), Hb, Sd, Y, IMM, IMG, R1 (r 24), the R2 (r ₂₅₎ and νd5 (ν _d32) is Are shown in Table 1. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 12 is a cross-sectional view along the optical axis of the optical configuration of the rear conversion lens according to Example 10 of the present invention. FIG. 26 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens mounted) according to Example 10.
As shown in FIG. 12, the rear conversion lens of Example 10 is composed of five lenses. In order from the object side, a positive first lens L1013 having a concave surface on the object side, a second lens L1014 having a negative refractive power having a convex surface on the object side, a third lens L1015 having a negative refractive power on the image side, an object The lens includes a fourth lens L1016 having negative refractive power having a concave surface on the side and a fifth lens L1017 having positive refractive power having both convex surfaces. In this example, the fifth lens component is the lens L1017. The configurations of the conversion lens holder, the flare stop, and the like are the same as those described in the first embodiment, and are therefore omitted.

  Next, numerical data of optical members constituting the rear conversion lens of Example 10 are shown. Since the numerical data of the master lens optical system combined with the rear conversion lens is the same as that shown in the numerical data 1 of the first embodiment, a description thereof will be omitted.

Numerical data 11
( Example 10: FIG. 12 )
f = 419.11mm Fno = 3.9 Magnification = 1.40
r ₂₄ = −5.646 × 10 ⁴
d ₂₄ = 1.8000 n _d24 = 1.80518 ν _d24 = 25.42
r ₂₅ = −84.3970
d ₂₅ = 0.1000
r ₂₆ = 121.0264
d ₂₆ = 1.2470 n _d26 = 1.81600 ν _d26 = 46.62
r ₂₇ = 17.8919
d ₂₇ = 0.9734
r ₂₈ = 22.2745
d ₂₈ = 3.0462 n _d28 = 1.59551 ν _d28 = 39.24
r ₂₉ = 104.9298
d ₂₉ = 2.4776
r ₃₀ = −36.4417
d ₃₀ = 0.9598 n _d30 = 1.78800 ν _d30 = 47.37
r ₃₁ = 347.4519
d ₃₁ = 0.1000
r ₃₂ = 27.2281
d ₃₂ = 4.3150 n _d32 = 1.48749 ν _d32 = 70.23
r ₃₃ = −112.3984
d ₃₃ = 35.2138
P = Imaging surface

Specifications of numerical values in Example _{10, Nd1 (n d24),} νd1 (ν d24), Hb, Sd, Y, IMM, IMG, R1 (r 24), the R2 (r ₂₅₎ and νd5 (ν _d32) is Are shown in Table 1. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

FIG. 13 is a sectional view taken along the optical axis of the optical configuration of the rear conversion lens according to Example 11 of the present invention. FIG. 27 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens mounted) according to Example 11.
As shown in FIG. 13, the rear conversion lens of Example 11 is composed of five lenses. In order from the object side, a positive first lens L1113 having a convex surface on the object side, a second lens L1114 having a negative refractive power having a convex surface on the object side, a third lens L1115 having a concave refractive power on the image side, an object The lens includes a fourth lens L1116 having a negative refractive power having a concave surface on the side and a fifth lens L1117 having a positive refractive power of both convex surfaces. In this example, the fifth lens component is the lens L1117. The configurations of the conversion lens holder, the flare stop, and the like are the same as those described in the first embodiment, and are therefore omitted.

  Next, numerical data of optical members constituting the master lens optical system and the rear conversion lens in Example 11 are shown.

Numerical data 12
( Example 11: FIG. 13 )
Master lens: f = 300mm Fno = 2.8 Half angle of view ω = 2.3 °
Rear conversion lens: f = 420.20mm Fno = 3.9 Magnification = 1.40
r ₁ = 248.8583
d ₁ = 6.2258 n _d1 = 1.74950 ν _d1 = 35.28
r ₂ = 149.7739
d ₂ = 2.1820
r ₃ = 133.6304
d ₃ = 1.49700 n _d3 = 18.5000 ν _d3 = 81.54
r ₄ = −317.0995
d ₄ = 0.5859
r ₅ = 130.9539
d ₅ = 14.4960 n _d5 = 1.49700 ν _d5 = 81.54
r ₆ = 938.4581
d ₆ = 7.4719
r ₇ = −399.8887
d ₇ = 6.0000 n _d7 = 1.83400 ν _d7 = 37.16
r ₈ = −5911.8564
d ₈ = 52.2724
r ₉ = −1176.4309
d ₉ = 9.5252 n _d9 = 1.84666 ν _d9 = 23.78
r ₁₀ = −139.4432
d ₁₀ = 3.5880 n _d10 = 1.63930 ν _d10 = 44.87
r ₁₁ = −8552.4362
d ₁₁ = 1.2541
r ₁₂ = −1073.3817
d ₁₂ = 3.4426 n _d12 = 1.69680 ν _d12 = 55.53
r ₁₃ = 93.0994
d ₁₃ = 36.8207
r ₁₄ = 86.4715
d ₁₄ = 3.5687 n _d14 = 1.80100 ν _d14 = 34.97
r ₁₅ = 57.0560
d ₁₅ = 1.6186
r ₁₆ = 58.0496
d ₁₆ = 12.1657 n _d16 = 1.49700 ν _d16 = 81.54
r ₁₇ = −190.3950
d ₁₇ = 5.220
r ₁₈ = ∞ (aperture)
d ₁₈ = 12.0000
r ₁₉ = −719.5271
d ₁₉ = 4.5680 n _d19 = 1.56732 ν _d19 = 42.82
r ₂₀ = 52.1479
d ₂₀ = 10.0933 n _d20 = 1.80610 ν _d20 = 40.92
r ₂₁ = 529.2439
d ₂₁ = 0.5526
r ₂₂ = 68.1373
d ₂₂ = 6.3521 n _d22 = 1.69680 ν _d22 = 55.53
r ₂₃ = 42.0858
d ₂₃ = 63.7437
r ₂₄ = 208.2204
d ₂₄ = 1.9185 n _d24 = 1.69895 ν _d24 = 30.13
r ₂₅ = −74.6641
d ₂₅ = 0.2000
r ₂₆ = 207.0994
d ₂₆ = 1.2697 n _d26 = 1.83481 ν _d26 = 42.71
r ₂₇ = 18.0551
d ₂₇ = 0.7334
r ₂₈ = 20.0340
d ₂₈ = 3.0594 n _d28 = 1.64769 ν _d28 = 33.79
r ₂₉ = 72.6052
d ₂₉ = 3.3278
r ₃₀ = −29.7020
d ₃₀ = 1.0887 n _d30 = 1.81600 ν _d30 = 46.62
r ₃₁ = −648.5360
d ₃₁ = 0.2000
r ₃₂ = 35.3965
d ₃₂ = 3.9557 n _d32 = 1.48749 ν _d32 = 70.23
r ₃₃ = −67.3038
d ₃₃ = 32.9991
P = Imaging surface

Specifications of numerical values in Examples _{11, Nd1 (n d24),} νd1 (ν d24), Hb, Sd, Y, IMM, IMG, R1 (r 24), the R2 (r ₂₅₎ and νd5 (ν _d32) is Are shown in Table 1. Table 2 shows numerical values obtained by applying and calculating these numerical values to the above conditional expressions.

Table 1 below shows numerical values of specifications in Examples 1 to 11 of the rear conversion lens of the present invention.
Table 1: Numerical values of specifications in each example
In Table 1 above, the correspondence between the specifications of the conditional expression and the numerical data in each example is as follows.
Nd1 the n _d24, vd1 the [nu _d24, R1 to r _24, R2 is the r _25, νd5 corresponds to [nu _d32.

Table 2 below shows numerical values obtained by applying and calculating the numerical values of the specifications in Examples 1 to 11 of the rear conversion lens of the present invention to the above conditional expressions.
Table 2: Values corresponding to conditional expressions in each example

The rear conversion lens of the present invention described above can be applied to a silver salt or digital single-lens reflex camera. These are exemplified below.
FIG. 15 is a schematic cross-sectional view of a single-lens reflex camera using a rear conversion lens and a master lens of the present invention in combination as a photographing lens. In the figure, reference numeral 1 denotes a single-lens reflex camera, 2 denotes a mount unit that allows the holder 5 of the master lens ML or the holder 4 of the rear conversion lens RCL to be attached to and detached from the single-lens reflex camera 1, and 3 denotes the master lens ML. The mount 5 is a mount part that allows the holder 5 to be attached to and detached from the holder 4 of the rear conversion lens RCL, and a screw type mount, a bayonet type mount (in this figure, a bayonet type mount is used) or the like. . Further, P is an image pickup surface such as an electronic image pickup device such as a CCD or a film, 6 is an eye (eye point) of an observer, and 7 is a quick light disposed between the image pickup lens and the image pickup surface P in the optical path 8 of the image pickup lens. A return mirror, 9 is a finder screen disposed on the light path reflected from the quick return mirror 7, 10 is a pentaprism, and 11 is a finder. Reference numerals 12, 15, and 18 are control circuits for adjusting the aperture, focal length, focusing, and the like. Reference numerals 13, 16 are electrical connections between the master lens ML and rear conversion lens RCL and the camera body, and the adjustment, An electrical contact 17 for transmitting a control signal, and a control unit 17 for the diaphragm S. The rear conversion lens of the present invention can be used as a photographing lens (rear conversion lens) of the single-lens reflex camera 1 having such a configuration.

It is sectional drawing which follows the optical axis which shows the optical structure which combined the rear conversion lens and master lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of the master lens used in combination with the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 1 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 2 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 3 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 4 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 5 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 6 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 7 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 8 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 9 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 10 of the rear conversion lens by this invention. It is sectional drawing which follows the optical axis which shows the optical structure of Example 11 of the rear conversion lens by this invention. FIG. 3 is a view of the rear conversion lens in Example 1 as viewed from the light incident side. It is a schematic sectional drawing of the single-lens reflex camera using the rear conversion lens and master lens of this invention. The spherical aberration, astigmatism, distortion and lateral chromatic aberration of the master lens used in combination with the rear conversion lens of the present invention are shown. 7 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 1 of the present invention. 7 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 2 of the present invention. 7 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 3 of the present invention. 7 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (with the master lens mounted) of Example 4 of the present invention. 10 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 5 of the present invention. 10 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 6 of the present invention. 10 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 7 of the present invention. 10 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 8 of the present invention. 10 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 9 of the present invention. 10 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the rear conversion lens (when the master lens is mounted) of Example 10 of the present invention. 10 shows spherical aberration, astigmatism, distortion and lateral chromatic aberration of the rear conversion lens (with the master lens mounted) of Example 11 of the present invention.

Explanation of symbols

ML Master lens RCL Rear conversion lens Ln Lens P Imaging surface S Aperture stop 1 Single-lens reflex camera 2, 3 Mount unit 4 Rear conversion lens holder 5 Master lens holder 6 Eyepoint 7 Quick return mirror 8 Optical path 9 Viewfinder screen 10 Penta Prism 11 Viewfinder 12, 15, 18 Control circuit 13, 16 Electrical contact point 17 Aperture control unit

Claims (9)

A rear conversion lens that can be connected between the master lens and the camera body, and that increases the focal length of the entire system relative to the focal length of the master lens,
The lens system part
From the object side,
A positive first lens having an absolute refractive power stronger on the image side than on the object side;
A negative second lens having a refractive power of an absolute value stronger on the image side than on the object side;
A positive third lens having a refractive power of an absolute value stronger on the object side than on the image side;
A negative fourth lens having a refractive power of an absolute value stronger on the object side than on the image side;
A positive fifth lens component;
A rear conversion lens that satisfies the following conditional expression:
Nd1> 1.69 (1)
Nd1 is the refractive index of the glass material of the first lens. The rear conversion lens according to claim 1, wherein the following conditional expression is satisfied.
νd 1 <31 (2)
Here, νd 1 is the Abbe number of the glass material of the first lens. The rear conversion lens according to claim 1, wherein the following conditional expression is satisfied.
-1.5 <Hb / Sd <-0.5 (3)
Where Hb is the rear principal point position of the rear conversion lens, and Sd is the distance from the object side surface of the first lens of the rear conversion lens to the image side surface of the image side lens.   4. The cemented lens according to claim 1, wherein the fifth lens component is a cemented lens including a biconvex positive refractive power lens and a negative refractive meniscus lens having a convex surface facing the image side. The rear conversion lens according to claim 1. 4. The fifth lens component according to claim 1, wherein the fifth lens component is only one biconvex positive refractive power lens made of a low dispersion glass material that satisfies the following conditional expression. 5. Rear conversion lens.
νd 5> 60 (4)
νd 5 is the Abbe number of the glass material of the fifth lens component.   6. The rear conversion according to claim 1, wherein a flare stop is provided between the first lens to the fifth lens component, or a coating having a function as a flare stop is provided on the lens surface. lens. When the master lens in a state of forming an image on the imaging surface of the camera body when directly attached to the camera body is attached to the camera body via the rear conversion lens,
The rear conversion lens according to any one of claims 1 to 6, wherein the following conditional expression is satisfied.
0.9 <IMM / IMG <1.02 (5)
Where IMM is the distance from the front surface of the first lens of the rear conversion lens to the master lens image plane position, and IMG is the distance from the final surface of the rear conversion lens to the image plane when the master lens is mounted. The rear conversion lens according to claim 1, wherein the following conditional expression is satisfied in a state where the master lens is attached to the camera body via the rear conversion lens.
Y / IMG <0.5 (6)
Y is the maximum image height on the imaging surface, and IMG is the distance from the final surface of the rear conversion lens to the image surface when the master lens is mounted. The rear conversion lens according to claim 1, wherein the first lens satisfies the following conditional expression.
-4.0 <(R2 + R1) / (R2-R1) <− 0.08 (7)
Where R1 is the radius of curvature of the object side surface of the first lens, and R2 is the radius of curvature of the image side surface of the first lens.