JP2013174651A - Attachment optical system and imaging device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an attachment optical system for obtaining satisfactory optical performance within various sizes of photographic ranges in the case of reimaging a primary image formed on a predetermined face by a photographic lens.SOLUTION: An attachment optical system for light-guiding a primary image formed on a predetermined face by an imaging lens to a photographic lens in a camera body is configured so as to be attachable/detachable to/from a camera body, and constituted of a first lens group with a negative refractive power and a second lens group with a positive refractive power from the predetermined face. When at least a partial lens group constituting the first lens group and the second lens group is moved to an optical axis direction, the photographic range of the primary image in the case of imaging the primary image formed on the predetermined face by the photographic lens is changed between a wide visual field and a narrow visual field. Thus, it is possible to appropriately set each of focal distances f1 and f2 of the first lens group and the second lens group.

Description

  The present invention relates to an attachment optical system that guides a light beam from a primary image formed on a predetermined surface by an imaging lens to a photographing lens in the camera body and is detachably mounted on the object side of the camera body.

  In imaging devices such as digital cameras and video cameras, solid-state imaging devices such as CCD sensors have been downsized, and at the same time, the entire size of the imaging device has been downsized. If the effective diameter of the image sensor is reduced, the focal length of the photographic lens is shortened in order to capture the same angle of view. As the focal length of the photographic lens decreases, the depth of field increases accordingly. For this reason, it has become difficult to obtain an image with a blurred background as in the case of using an imaging device having a large imaging element such as a 35 mm camera in an imaging device with a reduced size.

  In an image pickup apparatus using an image pickup device having a small effective surface, an optical system is known which can obtain an image having a shallow depth of field equivalent to that of a 35 mm camera. For example, an image forming lens is used to form an image with a shallow depth of field on a parallel plate having diffusion characteristics similar to those of an image sensor of a 35 mm camera. There is a method in which a primary image formed on a parallel plate is photographed in close proximity with a photographing lens in the camera body to obtain an image with a shallow subject depth. In this method, in order to re-form the formed primary image with the imaging lens by the imaging lens, an attachment optical system for close-up photography is required as a relay unit between the imaging lens and the imaging lens.

  An attachment optical system for close-up photography for removably attaching a primary image formed by an imaging lens to the object side of the imaging lens and re-imaging the imaging lens is known (Patent Document 1). In Patent Document 1, in order to re-image a primary image formed by a microscope objective lens with a photographic lens built in a digital camera, an imaging system in which an attachment optical system is arranged as a relay optical system between the objective lens and the photographic lens. An apparatus is disclosed.

  On the other hand, there is known a panoramic camera that changes various shooting areas shot by a camera by means of switching means (Patent Document 2). Japanese Patent Application Laid-Open No. 2004-228561 discloses that in a finder optical system for a panoramic camera, the shape of a finder field frame provided on the primary imaging surface of the finder optical system is changed in accordance with a change in an imaging region by an objective lens.

JP 2001-100093 A JP 05-002209 A

  A primary image formed on a predetermined surface by an imaging lens is guided to a photographing lens in the camera body via an attachment optical system, and in an imaging apparatus for photographing, 1 formed on a predetermined surface according to the specifications of the imaging lens. The size of the next image may be different. At this time, the entire apparatus has a method of preparing a plurality of attachment optical systems for close-up photography in accordance with the size of the primary image (from wide field to narrow field of view) and replacing each time according to the size of the primary image. It gets complicated.

  On the other hand, if the attachment optical system for close-up shooting can change the shooting range between wide-field shooting and narrow-field shooting, the attachment optical system can handle primary images of various sizes. . At this time, in order to guide the light beam from the primary image formed on the predetermined surface by the imaging lens to the photographing lens and obtain good optical performance in the photographing range of various sizes, the lens configuration of the attachment optical system is used. It is important to set it properly.

  In particular, if the optical configuration of the lens group constituting the attachment optical system is changed to change the shooting range of the primary image in various ways, the lens configuration is not appropriate. It becomes difficult to get.

  An object of the present invention is to provide an attachment optical system capable of obtaining good optical performance in a photographing range of various sizes when a primary image formed on a predetermined surface is re-imaged with a photographing lens.

The attachment optical system of the present invention is an attachment optical system for guiding a light beam from a primary image formed on a predetermined surface by an imaging lens to a photographing lens of a camera body,
The attachment optical system is detachable from the camera body, and the attachment optical system includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power. One lens group and all or a part of the second lens group move in the optical axis direction, so that a primary image formed on the predetermined surface is formed by the photographing lens. The shooting range changes between a wide field of view and a narrow field of view,
When the focal lengths of the first lens group and the second lens group are f1 and f2, respectively.
0.3 <| f1 | / f2 <0.8
It satisfies the following conditional expression.

  According to the present invention, when a primary image formed on a predetermined surface is re-imaged with a photographic lens, an attachment optical system is obtained that can obtain good optical performance in various photographic ranges.

Sectional view of the lens when the attachment optical system of Example 1 is attached to the photographing lens (A), (B), (C) Aberration diagrams of wide-field photography, intermediate-field photography, and narrow-field photography when the attachment optical system of Example 1 is attached to the photographing lens. Sectional view of the lens when the attachment optical system of Example 2 is attached to the photographing lens (A), (B), (C) Aberration diagrams of wide-field photography, intermediate-field photography, and narrow-field photography when the attachment optical system of Example 2 is attached to the photographing lens. Sectional view of the lens when the attachment optical system of Example 3 is attached to the photographing lens (A), (B), (C) Aberration diagrams of wide-field photography, intermediate-field photography, and narrow-field photography when the attachment optical system of Example 3 is attached to the photographing lens. Schematic diagram of main parts of an imaging apparatus of the present invention

  An attachment optical system of the present invention and an image pickup apparatus having the same will be described. The attachment optical system of the present invention guides a primary image formed on a predetermined surface such as a diffusive parallel plate by an imaging lens to a photographing lens in the camera body.

  The attachment optical system is detachable from the camera body. The attachment optical system includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power. By moving the first lens group and all or part of the second lens group in the optical axis direction, a primary image formed on a predetermined surface is formed on the surface of an image pickup device such as a CCD by a photographing lens. The photographing range of the primary image is changed between a wide field of view and a narrow field of view.

  In this embodiment, in order to obtain an image with a small depth of field with an imaging device having a small imaging device, a primary image formed by a focusing lens on a parallel plate (predetermined surface) having diffusion characteristics is used as an attachment optical system. Close-up photography with the taking lens. At this time, in order to re-image the primary image satisfactorily, the attachment optical system disposed between the photographing lens and the parallel plate is disposed so that the entrance pupil of the photographing lens and the exit pupil of the attachment optical system are close to each other. There is a need to. Otherwise, the amount of light around the screen will be insufficient or the amount of vignetting will increase.

  In general, in a photographing lens used for a video camera or a digital camera, the entrance pupil is located inside the lens system. For this reason, it is necessary to configure the off-axis light beam from the attachment optical system to converge so as to ensure an appropriate exit pupil distance. There are a plurality of imaging lenses having different imaging sizes as imaging lenses for forming a primary image on a parallel plate.

  In the present invention, in order to photograph this with one attachment optical system, the imaging range of the attachment optical system is reduced to a wide field of view and narrow according to the imaging size (primary image size) of the imaging lens for forming the primary image. It is configured to change between the field of view. In order to change the imaging range of the primary image by the attachment optical system, a lens group having a strong negative refractive power with a variable field of view and a lens group for correcting various aberrations that change when the imaging range changes, In total, two or more lens groups are arranged so as to be movable on the optical axis.

  Specifically, the attachment optical system of each embodiment has a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from a predetermined surface, and of these, at least two or more lens groups are included. Is configured to be movable on the optical axis. The first lens group having a strong negative refractive power is arranged on the most predetermined surface side of the attachment optical system, and the first lens group is moved on the optical axis, so that an off-axis ray is photographed while changing the photographing range. It is made to enter the lens at an appropriate height.

  Further, by moving part or all of the second lens group having a positive refractive power as a whole, correcting various aberrations that change when the photographing range changes, and converging off-axis rays with respect to the photographing lens, An appropriate exit pupil distance is secured.

  1, 3 and 5 are lens cross-sectional views when the attachment optical system according to Embodiments 1 to 3 of the present invention is detachably mounted on the object side of a photographing lens in a camera body. The lens cross-sectional view shows a wide-field shooting. FIG. 7 is a schematic view when the attachment optical system of the present invention is detachably mounted on the camera body between the imaging lens and the camera body.

  In the lens cross-sectional view, At is an attachment optical system, and includes a first lens group At1 having a negative refractive power and a second lens group At2 having a positive refractive power. Zm is a taking lens in the camera body to which the attachment optical system At is attached. In the photographic lens Zm, SP is a diaphragm or light amount adjusting device, GB is a glass block such as a face plate or a low-pass filter, IP is an image plane, and an image sensor is arranged. Zmf is a focus lens group.

  In the lens cross-sectional view, the left side is a predetermined surface (object side) and the right side is an image side. In each embodiment, a primary image (for example, an image formed on a diffusing plate) formed on a predetermined surface by the imaging lens is re-imaged on the image plane IP by the attachment optical system At and the photographing lens Zm.

  In each embodiment, as shown in the lens cross-sectional views, the positions in the optical axis direction of at least two lens groups among the lens groups constituting the attachment optical system At are changed. As a result, the imaging range of the primary image when the primary image formed on the predetermined surface is formed on the image sensor IP by the imaging lens Zm is changed. That is, the imaging range of the primary image is changed to wide field imaging (see each lens cross section), intermediate field imaging, and narrow field imaging.

  2, 4 and 6 are graphs showing various aberrations when a primary image on a predetermined surface is formed in a state where the attachment optical system shown in Embodiments 1 to 3 of the present invention is mounted on a photographing lens. . In the aberration diagrams, (A), (B), and (C) show the cases of wide-field photography, intermediate-field photography, and narrow-field photography when a primary image on a predetermined surface is formed by the photographing lens Zm.

  In the spherical aberration diagram, d and g indicate d-line and g-line. In the astigmatism diagram, ΔM and ΔS indicate the meridional image surface and the sagittal image surface at the d-line. The lateral chromatic aberration represents the g-line with respect to the d-line. Also, Fno. Is the F number, and ω is the half angle of view (degrees).

  Next, an embodiment of an imaging apparatus using the attachment optical system of the present invention will be described with reference to FIG. In FIG. 7, reference numeral 10 denotes an imaging lens, which forms (forms) a primary image (object image) on a predetermined surface, for example, a diffusion plate (predetermined surface) 21 made of a diffusive parallel plate. ing. Reference numeral 20 denotes an attachment optical system, which is detachably attached to the object side (imaging lens 10 side) of the camera body 30 and is a photographic lens that follows the light beam from the object image formed on the predetermined surface 21 by the imaging lens 10. 31 is guided. The attachment optical system 20 includes a first lens group 22 having a negative refractive power and a second lens group 23 having a positive refractive power.

  Reference numeral 30 denotes a camera body, which includes a photographing lens 31 and a solid-state imaging device (imaging device) 32 such as a CCD sensor or a CMOS sensor that receives an image formed by the photographing lens 31.

  In this embodiment, the imaging lens 10 and the attachment optical system 20 can be attached to and detached from the object side of the camera body 30. The diffusion plate 21 having diffusion characteristics and the attachment optical system 20 may be integrated to be detachable from the camera body 30.

  In the present embodiment, a primary image (object image) imaged on the diffusion plate 21 by the imaging lens 10 is reconnected to the image sensor (CCD) 32 by the imaging lens 31 in the camera body 30 via the attachment optical system 20. I image. At this time, the position (optical arrangement) of the lens group constituting the attachment optical system 20 in the optical axis direction is changed. Thereby, the imaging range of the primary image when the primary image formed on the predetermined surface 21 is formed on the image sensor 32 by the imaging lens 31 is changed. That is, the imaging range is changed by the attachment optical system 20.

  Note that an aerial image formed by the imaging lens 10 without using the diffusing plate 21 may be re-imaged on the imaging element 32 by the imaging lens 31 in the camera body 30 via the attachment optical system 20.

As described above, by applying the attachment optical system of the present invention to an image pickup apparatus having an image pickup device such as a video camera, a small-size image pickup apparatus having a high optical performance in which a photographing range can be easily changed is realized. In each embodiment, the focal lengths of the first lens group At1 and the second lens group At2 are f1 and f2, respectively. At this time,
0.3 <| f1 | / f2 <0.8 (1)
The following conditional expression is satisfied.

  Conditional expression (1) appropriately defines the ratio of the focal length of the first lens unit At1 and the focal length of the second lens unit At2 that has the effect of changing the imaging range of the primary image by the attachment optical system At. is there. If the lower limit of conditional expression (1) is exceeded and the focal length of the first lens unit At1 becomes too short, curvature of field increases at the time of narrow-field imaging, and this correction becomes difficult. On the other hand, when the focal length of the first lens unit At1 is increased beyond the upper limit, various aberrations can be easily corrected.

  However, the movement amount of the first lens unit At1 must be increased in order to ensure a sufficient amount of change in the photographing range. As a result, the lens configuration length of the attachment optical system At increases, which is not preferable. By adopting the above configuration, it is possible to achieve an attachment optical system for close-up shooting that can easily change the shooting range. In each embodiment, it is more preferable to satisfy one or more of the following conditions.

  The distance from the object-side lens surface of the first lens unit At1 to the object-side lens surface of the second lens unit At2 when the imaging range of the primary image by the photographic lens Zm is a wide field of view is d1L. The distance from the object-side (predetermined surface) lens surface of the first lens unit At1 to the object-side lens surface of the second lens unit At2 when the imaging range of the primary image by the imaging lens Zm is a narrow field of view is d1N. .

  The distance from the object-side lens surface of the first lens group At to the predetermined surface when the photographing range of the primary image by the photographing lens Zm is a narrow field is d0N (the sign of the distance d0N is positive). The second lens group At2 includes a twenty-first lens group At21 having a negative refractive power and a twenty-second lens group At22 having a positive refractive power in order from the object side to the image side with the largest air gap. The focal length of the 21st lens group At21 is set to f21. The focal length of the 22nd lens group At22 is set to f22. At this time, it is preferable to satisfy one or more of the following conditions.

0.2 <(d1N−d1L) / | f1 | <0.8 (2)
0.04 <d0N / | f1 | <0.10 (3)
1.5 <f21 / f2 <5.0 (4)
0.50 <f22 / f2 <0.95 (5)
Next, the technical meaning of each conditional expression will be described.

  Conditional expression (2) appropriately defines the focal length of the first lens unit At1 having the action of changing the imaging range of the primary image by the attachment optical system At and the amount of movement when the imaging range is changed. . If the lower limit of conditional expression (2) is exceeded and the focal length of the first lens unit At1 becomes too long, it will be difficult to secure a sufficient change in the imaging range, and the amount of movement when changing the imaging range must be increased. I must. As a result, the lens configuration length of the attachment optical system At is undesirably increased.

  On the other hand, if the focal length of the first lens group At is too short beyond the upper limit, the change in the imaging range can be secured sufficiently, but the field curvature increases at the time of narrow field imaging, and this correction becomes difficult.

  Conditional expression (3) appropriately sets the ratio of the distance between the first lens surface of the first lens unit At1 and the predetermined surface (diffusion surface) when the shooting range with respect to the focal length of the first lens unit At1 is narrow. It prescribes. If the lower limit of conditional expression (3) is exceeded and the focal length of the first lens unit At1 becomes too long, it is difficult to ensure a sufficient amount of change in the shooting range. On the other hand, if the focal length of the first lens unit At1 is reduced beyond the upper limit, it is easy to obtain a sufficient change in the shooting range, but the field curvature increases during narrow field shooting, and this correction becomes difficult. .

  Conditional expression (4) relates to the ratio between the focal length of the 21st lens group At21 and the focal length of the second lens group At2 constituting the second lens group At2 of the attachment optical system At. If the upper limit of conditional expression (4) is exceeded and the focal length of the twenty-first lens unit At21 becomes too long, lateral chromatic aberration will increase, making this correction difficult. On the other hand, if the lower limit is exceeded and the focal length of the 21st lens group At21 becomes too short, the incident height of off-axis rays in the 21st lens group At21 becomes too high, and the exit pupil of the attachment optical system suitable for the photographing lens It becomes difficult to secure a long distance.

Conditional expression (5) relates to the ratio between the focal length of the 22nd lens group At22 and the focal length of the second lens group At2 constituting the second lens group At2 of the attachment optical system At. If the upper limit of conditional expression (5) is exceeded and the focal length of the 22nd lens group At22 becomes too long, it will be difficult to ensure a long exit pupil distance of the attachment optical system suitable for the taking lens. On the other hand, if the focal length of the 22nd lens unit At22 is reduced beyond the lower limit, it becomes easy to ensure a long exit pupil distance, but the field curvature becomes large.
Preferably, the numerical value range of the conditional expression is set as follows.

0.35 <| f1 | / f2 <0.60 (1a)
0.4 <(d1N−d1L) / f1 <0.7 (2a)
0.05 <d0N / | f1 | <0.09 (3a)
1.6 <| f21 | / f2 <4.5 (4a)
0.60 <f22 / f2 <0.95 (5a)
More preferably, if the numerical ranges of the conditional expressions (1a) to (5a) are set as follows, it becomes easy to obtain the maximum effect obtained by the conditional expressions described above.

0.4 <| f1 | / f2 <0.5 (1b)
0.50 <(d1N−d1L) / f1 <0.66 (2b)
0.06 <d0N / | f1 | <0.09 (3b)
1.8 <| f21 | / f2 <4.5 (4b)
0.70 <f22 / f2 <0.91 (5b)
In each embodiment, as described above, each lens group of the attachment optical system is configured to realize a change in the photographing range from a wide field of view to a narrow field of view, and a small attachment optical system in which various aberrations are well corrected. Have gained. In each embodiment, the first lens group includes a cemented lens in which a negative lens and a positive lens are cemented.

  The twenty-first lens group At21 preferably has at least one lens having a negative refractive power and one or more lenses having a positive refractive power. According to this, the 21st lens group At21 can be achromatic, and it becomes easy to correct the variation of the chromatic aberration of magnification accompanying the change of the photographing range. Further, by arranging the 22nd lens unit At22 having a positive refractive power on the image side of the 21st lens unit At21, it becomes easy to ensure a long exit pupil distance of the attachment optical system suitable for the photographing lens. The 22nd lens group At22 is composed of a single positive lens.

  In each embodiment, the focus lens Zmf of the photographing lens Zm arranged on the image side of the attachment optical system At corrects the focus movement that occurs when the photographing range of the primary image by the attachment optical system At is changed. Also good.

  Common video cameras, digital cameras, and the like often have means for focusing, and if this is used, it is not necessary to mount a focusing mechanism in the attachment optical system, and miniaturization becomes easy.

  Next, the lens configuration of the attachment optical system At of each embodiment will be described. In Example 1 of FIG. 1, the first lens unit At1 having negative refractive power constituting the attachment optical system At is moved in the direction of the optical axis as indicated by an arrow, and diffusion is performed by the photographing lens 31 in the camera body 30. The shooting range on the surface 21 is changed from a wide field of view to a narrow field of view. Then, the 21st lens unit At21 having a negative refractive power closest to the object side, which constitutes the second lens unit At2 having a positive refractive power as a whole on the image side from the first lens unit At1, is moved in the optical axis direction as indicated by an arrow. Thus, aberration fluctuations accompanying changes in the shooting range are corrected. An appropriate exit pupil distance is secured for the taking lens 31.

  In Example 2 of FIG. 3, the first lens group At1 having negative refractive power that constitutes the attachment optical system At is moved in the optical axis direction as indicated by an arrow, and diffusion is performed by the photographing lens 31 in the camera body 30. The shooting range on the surface 21 is changed from a wide field of view to a narrow field of view. Then, the second lens unit At2 having a positive refractive power as a whole on the image side from the first lens unit At1 is moved integrally in the direction of the optical axis as indicated by an arrow, thereby correcting aberration fluctuations associated with a change in the imaging range and shooting. An appropriate exit pupil distance is secured for the lens 31.

  In the third embodiment, the first lens unit At1 having negative refractive power constituting the attachment optical system At is moved in the direction of the optical axis as shown by an arrow on the diffusion surface 21 on which an image is formed by the photographing lens 31 in the camera body 30. The shooting range is changed from a wide field of view to a narrow field of view. Then, the 21st lens unit At21 having a negative refractive power closest to the object side, which constitutes the second lens unit At2 having a positive refractive power as a whole on the image side from the first lens unit At1, and the first refractive power having a positive refractive power on the image side. The 22 lens group At22 is moved along different trajectories in the optical axis direction as indicated by arrows. As a result, an appropriate exit pupil distance is secured for the photographic lens 31 while correcting aberration fluctuations accompanying changes in the photographic range.

  In each embodiment, the photographing lens 31 uses a common photographing lens, and focus correction is performed by the focus lens Zmf of the photographing lens 31.

  An imaging apparatus having an attachment optical system and a photographing lens of the present invention and an image sensor for receiving an image formed by these optical systems can be configured. In recent years, a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), and the like are mainly used as an imaging device in order to digitally process an image. In each of the embodiments, an image pickup device is configured using an image pickup element corresponding to this.

  Further, in the image pickup apparatus of each embodiment, the aberration is corrected by an electric correction unit. Unlike silver-salt film, this uses the characteristics that digital cameras can acquire images as digital data, and image conversion processing is performed on images obtained from the photographic lens to reduce various aberrations. Have gained. Electrical aberration correction includes electronic distortion correction and electronic magnification chromatic aberration correction. In electronic distortion correction, distortion is reduced by enlarging or reducing the image by an amount determined for each zoom position, subject distance, and image height, and an image with less distortion is obtained.

  In the electronic magnification chromatic aberration correction, among the red R, green G, and blue B signals divided by the color filter of the image sensor, for example, the green G is used as a reference, and the shift of the red R and blue B with respect to the green G is the zoom position. Correction is performed for each pixel in accordance with the subject distance and the image height. As a result, an image with little chromatic aberration of magnification is obtained. By assuming that these electrical aberration corrections are performed, it is easy to reduce the number of lenses in the entire optical system, and as a result, the overall lens length is shortened and the lens system is downsized. In addition, good aberration correction is facilitated without using an aspherical surface or anomalous dispersion glass.

  As described above, according to each embodiment, it is possible to realize a small attachment optical system having a short overall length while properly correcting various aberrations. In addition, it is possible to obtain an image having a shallow depth of field with a photographic lens having a small image pickup element by variously changing the photographic range while properly correcting various aberrations.

In each embodiment, the following configuration may be adopted.
-It is not limited to the shape and the number of glasses shown in the examples, but should be changed as appropriate.
-The material of the aspherical lens is not limited to glass material, but a hybrid type aspherical lens in which an aspherical surface is formed with a resin material on the spherical lens surface (with an aspherical component on it) or an aspherical lens made of plastic material. Use it.
-Move some lenses and lens groups so that they have a component in the direction perpendicular to the optical axis, thereby correcting image blur due to vibration such as camera shake.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. For example, the attachment optical system of the present invention can be mounted in addition to the photographing lens shown in the above-described embodiments.

Next, Numerical Examples 1 to 3 respectively corresponding to Embodiments 1 to 3 of the attachment optical system of the present invention will be shown. Numerical Examples 1 to 3 show the case where the attachment optical system At is attached to the photographing lens Zm.

  In each numerical example, i indicates the order of surfaces from the object side (predetermined surface). ri is the radius of curvature of the i-th surface from the object side, di is the surface distance between the i-th surface and the i + 1-th surface from the object side, and ndi is the d-line of the material of the i-th lens The refractive index, νdi, indicates the Abbe number of the i-th lens at the d-line. An attachment optical system extends from the first lens surface to the eighth lens surface. The ninth and subsequent lens surfaces are photographing lenses.

  The total lens length is a value obtained by adding back focus to the distance from the forefront lens to the last lens surface. In the attachment optical system, the value when the entire lens length is attached to the photographing lens is shown. BF (back focus) represents the distance from the lens final surface to the paraxial image plane in terms of the air conversion length. The aspheric shape has an X axis in the optical axis direction, an H axis perpendicular to the optical axis, a positive light traveling direction, R is a paraxial radius of curvature, and each aspheric coefficient is K, A3, A4, A5, A6, When A7, A8, A9, A10, A11, A12,

It is expressed by the following formula. Further, for example, "e-Z" means "10 ^-Z". The aspherical surfaces are marked with an asterisk (*) on the right side of the surface number in each table. In each numerical example of the photographing lens, the four surfaces closest to the image side are planes corresponding to the optical block G. In each embodiment, the distance D0N on the optical path from the parallel flat diffuser plate to the lens surface closest to the object side of the attachment optical system at the time of narrow-field imaging is 3.5. Table 1 shows the relationship between the above-described conditional expressions and various numerical values in the numerical examples.

[Numerical Example 1]
Unit mm

Surface data surface number rd nd νd
1 -84.890 3.00 1.88300 40.8
2 40.625 4.75 1.48749 70.2
3 171.935 (variable)
4 -275.458 2.50 1.84666 23.8
5 89.049 12.28 1.51633 64.1
6 -116.825 (variable)
7 294.427 12.77 1.83481 42.7
8 -107.902 5.0
9 279.974 3.20 1.84666 23.9
10 78.637 1.78
11 103.173 7.87 1.59319 67.9
12 -482.657 0.20
13 59.095 8.61 1.49700 81.5
14 503.967 0.20
15 54.154 4.55 1.83481 42.7
16 110.728 36.40
17 67.985 1.15 2.00069 25.5
18 10.925 3.84
19 111.580 1.00 1.85135 40.1
20 * 30.012 2.66
21 -26.566 0.85 1.77250 49.6
22 40.759 0.86
23 31.027 3.10 1.94595 18.0
24 -55.061 12.44
25 (Aperture) ∞ 2.73
26 89.535 0.80 1.88300 40.8
27 15.440 4.20 1.84666 23.9
28 -25.249 0.14
29 -22.306 0.80 2.00330 28.3
30 66.150 4.80
31 * 47.065 3.60 1.58313 59.4
32 * -26.835 0.20
33 -205.644 2.00 1.48749 70.2
34 -34.516 0.80 1.80518 25.4
35 -229.787 (variable)
36 * 30.536 3.60 1.58313 59.4
37 * -48.513 0.20
38 90.175 0.90 1.92286 18.9
39 28.749 3.50 1.51633 64.1
40 -37.079 (variable)
41 ∞ 3.73 1.51633 64.1
42 ∞ 1.50
43 ∞ 20.00 1.58913 61.1
44 ∞ 0.5
Image plane ∞

Aspheric data 20th surface
K = -1.15140e + 001 A 4 = 5.79349e-005 A 6 = -1.13010e-007 A 8 = 1.55836e-009 A10 = 2.86348e-012 A12 = -4.39464e-015

No. 31
K = 4.24639e + 000
A 3 = 1.88268e-005 A 5 = -2.08701e-006 A 7 = -3.11766e-009 A 9 = 1.51363e-010 A11 = -8.73564e-013

32nd page
K = -4.83221e + 000
A 3 = 1.76699e-006 A 5 = -3.72328e-006 A 7 = 2.17282e-008 A 9 = -7.42060e-011

36th page
K = -4.95770e-003 A 4 = 1.93615e-005 A 6 = -2.26752e-007 A 8 = 1.96720e-009 A10 = 1.98174e-011

37th page
K = -7.16370e + 000 A 4 = 3.03042e-005 A 6 = -2.02825e-007 A 8 = 1.98951e-009 A10 = 2.14017e-011

Various data
Wide field Medium Narrow field focal length 12.90 15.56 16.57
F number 2.29 2.30 2.31
Angle of view 13.21 11.01 10.36
Image height 3.03 3.03 3.03
Total lens length 252.47 269.45 273.96
BF 25.12 23.42 22.82

d 3 39.94 61.39 66.50
d 6 19.76 15.30 14.70
d35 10.37 12.06 12.66
d40 8.07 6.38 5.78

Zoom lens group data group Start surface Focal length
1 1 -42.80
2 4 -472.30
3 7 95.98
4 9 -142.61
5 36 25.48
6 41 ∞

[Numerical Example 2]
Unit mm

Surface data surface number rd nd νd
1 -86.497 3.00 1.88300 40.8
2 71.744 3.34 1.48749 70.2
3 212.137 (variable)
4 -256.263 2.50 1.84666 23.8
5 72.537 11.00 1.51633 64.1
6 -162.049 20.00
7 356.052 12.79 1.83481 42.7
8 -97.790 (variable)
9 279.974 3.20 1.84666 23.9
10 78.637 1.78
11 103.173 7.87 1.59319 67.9
12 -482.657 0.20
13 59.095 8.61 1.49700 81.5
14 503.967 0.20
15 54.154 4.55 1.83481 42.7
16 110.728 38.41
17 67.985 1.15 2.00069 25.5
18 10.925 3.84
19 111.580 1.00 1.85135 40.1
20 * 30.012 2.66
21 -26.566 0.85 1.77250 49.6
22 40.759 0.86
23 31.027 3.10 1.94595 18.0
24 -55.061 10.43
25 (Aperture) ∞ 2.73
26 89.535 0.80 1.88300 40.8
27 15.440 4.20 1.84666 23.9
28 -25.249 0.14
29 -22.306 0.80 2.00330 28.3
30 66.150 4.80
31 * 47.065 3.60 1.58313 59.4
32 * -26.835 0.20
33 -205.644 2.00 1.48749 70.2
34 -34.516 0.80 1.80518 25.4
35 -229.787 (variable)
36 * 30.536 3.60 1.58313 59.4
37 * -48.513 0.20
38 90.175 0.90 1.92286 18.9
39 28.749 3.50 1.51633 64.1
40 -37.079 (variable)
41 ∞ 3.73 1.51633 64.1
42 ∞ 1.50
43 ∞ 20.00 1.58913 61.1
44 ∞ 0.5
Image plane ∞

Aspheric data 20th surface
K = -1.15140e + 001 A 4 = 5.79349e-005 A 6 = -1.13010e-007 A 8 = 1.55836e-009 A10 = 2.86348e-012 A12 = -4.39464e-015

No. 31
K = 4.24639e + 000
A 3 = 1.88268e-005 A 5 = -2.08701e-006 A 7 = -3.11766e-009 A 9 = 1.51363e-010 A11 = -8.73564e-013

32nd page
K = -4.83221e + 000
A 3 = 1.76699e-006 A 5 = -3.72328e-006 A 7 = 2.17282e-008 A 9 = -7.42060e-011

36th page
K = -4.95770e-003 A 4 = 1.93615e-005 A 6 = -2.26752e-007 A 8 = 1.96720e-009 A10 = 1.98174e-011

37th page
K = -7.16370e + 000 A 4 = 3.03042e-005 A 6 = -2.02825e-007 A 8 = 1.98951e-009 A10 = 2.14017e-011

Various data
Wide field Medium Narrow field focal length 15.25 19.12 20.56
F number 2.32 2.33 2.34
Angle of View 11.23 9.00 8.38
Image height 3.03 3.03 3.03
Total lens length 252.46 269.56 273.96
BF 25.82 23.44 22.52

d 3 31.91 56.53 63.88
d 8 15.46 7.94 5.00
d35 9.67 12.05 12.96
d40 8.77 6.39 5.48

Zoom lens group data group Start surface Focal length
1 1 -54.86
2 4 122.83
3 9 -166.90
4 36 25.48
5 41 ∞

[Numerical Example 3]
Unit mm

Surface data surface number rd nd νd
1 -92.104 3.00 1.88300 40.8
2 48.050 5.45 1.48749 70.2
3 197.570 (variable)
4 -354.029 2.50 1.84666 23.8
5 79.949 12.19 1.51633 64.1
6 -154.340 (variable)
7 310.973 13.03 1.83481 42.7
8 -102.110 (variable)
9 279.974 3.20 1.84666 23.9
10 78.637 1.78
11 103.173 7.87 1.59319 67.9
12 -482.657 0.20
13 59.095 8.61 1.49700 81.5
14 503.967 0.20
15 54.154 4.55 1.83481 42.7
16 110.728 37.16
17 67.985 1.15 2.00069 25.5
18 10.925 3.84
19 111.580 1.00 1.85135 40.1
20 * 30.012 2.66
21 -26.566 0.85 1.77250 49.6
22 40.759 0.86
23 31.027 3.10 1.94595 18.0
24 -55.061 11.68
25 (Aperture) ∞ 2.73
26 89.535 0.80 1.88300 40.8
27 15.440 4.20 1.84666 23.9
28 -25.249 0.14
29 -22.306 0.80 2.00330 28.3
30 66.150 4.80
31 * 47.065 3.60 1.58313 59.4
32 * -26.835 0.20
33 -205.644 2.00 1.48749 70.2
34 -34.516 0.80 1.80518 25.4
35 -229.787 (variable)
36 * 30.536 3.60 1.58313 59.4
37 * -48.513 0.20
38 90.175 0.90 1.92286 18.9
39 28.749 3.50 1.51633 64.1
40 -37.079 (variable)
41 ∞ 3.73 1.51633 64.1
42 ∞ 1.50
43 ∞ 20.00 1.58913 61.1
44 ∞ 0.5
Image plane ∞

Aspheric data 20th surface
K = -1.15140e + 001 A 4 = 5.79349e-005 A 6 = -1.13010e-007 A 8 = 1.55836e-009 A10 = 2.86348e-012 A12 = -4.39464e-015

No. 31
K = 4.24639e + 000
A 3 = 1.88268e-005 A 5 = -2.08701e-006 A 7 = -3.11766e-009 A 9 = 1.51363e-010 A11 = -8.73564e-013

32nd page
K = -4.83221e + 000
A 3 = 1.76699e-006 A 5 = -3.72328e-006 A 7 = 2.17282e-008 A 9 = -7.42060e-011

36th page
K = -4.95770e-003 A 4 = 1.93615e-005 A 6 = -2.26752e-007 A 8 = 1.96720e-009 A10 = 1.98174e-011

37th page
K = -7.16370e + 000 A 4 = 3.03042e-005 A 6 = -2.02825e-007 A 8 = 1.98951e-009 A10 = 2.14017e-011

Various data Zoom ratio 1.33
Wide field Medium Narrow field focal length 14.43 17.84 19.25
F number 2.34 2.35 2.36
Angle of view 11.86 9.64 8.94
Image height 3.03 3.03 3.03
Total lens length 252.46 270.41 273.96
BF 25.39 23.40 22.49

d 3 34.24 57.42 65.59
d 6 18.64 15.56 14.74
d 8 10.95 8.79 4.99
d35 10.09 12.08 12.99
d40 8.35 6.35 5.44

Zoom lens group data group Start surface Focal length
1 1 -48.52
2 4 -332.83
3 7 93.42
4 9 -150.62
5 36 25.48
6 41 ∞

At Attachment Optical System At1 First Lens Group At2 Second Lens Group At21 21st Lens Group At22 22nd Lens Group Zm Shooting Lens Group Zmf with Attachment Optical System Focusing Lens Group for Shooting Lens Group with Attachment Optical System

Claims (9)

An attachment optical system for guiding a light beam from a primary image formed on a predetermined surface by an imaging lens to a photographing lens of a camera body,
The attachment optical system is detachable from the camera body, and the attachment optical system includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power. One lens group and all or a part of the second lens group move in the optical axis direction, so that a primary image formed on the predetermined surface is formed by the photographing lens. The shooting range changes between a wide field of view and a narrow field of view,
When the focal lengths of the first lens group and the second lens group are f1 and f2, respectively.
0.3 <| f1 | / f2 <0.8
An attachment optical system characterized by satisfying the following conditional expression: The distance from the object-side lens surface of the first lens group to the object-side lens surface of the second lens group when the photographing range of the primary image by the photographing lens is a wide field of view is d1L, and 1 by the photographing lens. When the distance from the object-side lens surface of the first lens group to the object-side lens surface of the second lens group when the imaging range of the next image is a narrow field is d1N,
0.2 <(d1N-d1L) / | f1 | <0.8
The attachment optical system according to claim 1, wherein the following conditional expression is satisfied. When the distance from the lens surface on the object side of the first lens group to the predetermined surface is d0N when the photographing range of the primary image by the photographing lens is a narrow field of view,
0.04 <d0N / | f1 | <0.10
The attachment optical system according to claim 1, wherein the following conditional expression is satisfied.   The second lens group includes a 21st lens group having a negative refractive power and a 22nd lens group having a positive refractive power in order from the predetermined surface side with the largest air gap, and the 21st lens group includes at least The attachment optical system according to any one of claims 1 to 3, further comprising at least one lens having a negative refractive power and one lens having a positive refractive power. When the focal length of the 21st lens group is f21,
1.5 <f21 / f2 <5.0
The attachment optical system according to claim 4, wherein the following conditional expression is satisfied. When the focal length of the 22nd lens group is f22,
0.50 <f22 / f2 <0.95
The attachment optical system according to claim 4, wherein the following conditional expression is satisfied.   The attachment optical system guides a light beam from a primary image formed on a diffusive parallel plate by an imaging lens detachably mounted on the object side to the photographing lens. Item 7. The attachment optical system according to any one of Items 1 to 6. 8. An image forming lens for forming an image of a subject on a predetermined surface, a camera body having a photographing lens, and between the image forming lens and the camera body and detachable from the camera body. Or the attachment optical system according to claim 1,
The attachment optical system guides a light beam from a primary image formed on a predetermined surface by the imaging lens to the photographing lens,
The imaging apparatus, wherein the imaging lens re-images the primary image on an imaging device using a light beam from the attachment optical system.   The imaging apparatus according to claim 8, wherein an aberration caused by an optical system included in the imaging apparatus is corrected by an electrical correction unit.