JP2007212677A - Relay type finder optical system and imaging apparatus having same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact relay type finder optical system suitable for a digital still camera or a single-lens reflex camera or the like. <P>SOLUTION: The relay type finder optical system M has relay lens groups 3 and 4 for forming a secondary image I2 from a primary image I1 and having positive refractive power, and eyepiece lens groups 5 and 6 for observing the secondary image I2 and having positive refractive power in order from an object side along an optical axis. The relay lens group comprises a relay front group 3 and a relay rear group 4 in order from the object side along the optical axis. An optical path from the primary image I1 crosses on an optical path between the relay front group 3 and the relay rear group 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a relay type finder optical system used in a digital still camera, a single-lens reflex camera, or the like.

Conventionally, a relay type finder optical system has been proposed in order to reduce the size of a finder optical system such as a single-lens reflex camera (for example, see Patent Document 1).
Japanese Patent Application Laid-Open No. 1-1101534.

  However, the relay type finder optical system disclosed in Patent Document 1 has a configuration in which the light beam from the focusing screen intersects the light beam to the eyepiece lens group between the relay lens group and the eyepiece lens group. To prevent the lens group and the eyepiece lens group from interfering with the light flux from the focusing screen, it is necessary to make a large air gap between the relay lens group and the eyepiece lens group. There is a problem that is difficult.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a small relay-type finder optical system suitable for a digital still camera, a single-lens reflex camera, or the like. Moreover, it aims at providing the imaging device which comprises this relay type | formula finder optical system.

  In order to solve the above problems, the present invention observes the secondary image having a positive refractive power for forming a secondary image from a primary image in order from the object side along the optical axis, and the secondary image. An eyepiece lens group having a positive refractive power, and the relay lens group includes, in order from the object side along the optical axis, a relay front group and a relay rear group, and an optical path from the primary image is There is provided a relay type finder optical system characterized by having an optical means for crossing in a light path between a relay front group and the relay rear group.

  The present invention also provides an imaging apparatus comprising the relay type finder optical system.

  ADVANTAGE OF THE INVENTION According to this invention, the small relay type | formula finder optical system suitable for a digital still camera, a single-lens reflex camera, etc. can be provided. Moreover, the imaging device provided with this relay type finder optical system can be provided.

  Hereinafter, an imaging device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an imaging apparatus according to the present invention having a relay type finder optical system according to the present invention to be described later.

  In FIG. 1, an imaging apparatus 10 (for example, a single-lens reflex camera) according to the present invention receives light from a subject (not shown) through a photographing lens 11 and enters a quick return mirror 12, and is reflected and primary. A primary image is formed on the focusing screen I1 arranged on the image plane. The light beam from the subject image formed on the focusing screen I1 enters a relay type finder optical system M described later and is observed by the photographer through the finder window 14 behind the imaging device 10. The photographer observes the subject image and presses a release button (not shown), so that the quick return mirror 12 is retracted from the optical path of the taking lens 11 and the shutter (not shown) operates, and an image pickup device (for example, a CCD or a CMOS). 15 and is recorded in a memory (not shown). The recorded image is displayed on the liquid crystal monitor 16 on the back and confirmed by the photographer. In this way, the imaging apparatus 10 having the relay type finder optical system M according to the present invention described later is configured.

  Since the imaging apparatus 10 according to the present invention incorporates a relay-type finder optical system M, which will be described later, the position of the optical axis I11 of the photographing lens 11 and the position of the optical axis IP of the eyepiece group of the relay-type finder optical system M. Thus, it is possible to make it easier to observe the subject image displayed on the liquid crystal monitor 16 and various information of the imaging device 10. In addition, since the small relay type finder optical system M is used, a smaller image pickup apparatus 10 can be configured.

  Further, the imaging apparatus 10 according to the present invention is a subject image erecting from the finder window 14 by the quick return mirror 12 in the imaging apparatus 10 and the three reflecting surfaces built in the relay type finder optical system M. Can be observed by the photographer.

  Next, the relay type finder optical system M according to the embodiment of the present invention will be described with reference to FIG. 1 and the accompanying drawings.

(First embodiment)
FIG. 2 is a schematic configuration diagram of the relay type finder optical system M according to the first embodiment of the present invention.

  In FIG. 2, the light beam from the focusing screen I1 on which the primary image of the imaging device 10 is formed is forward of the imaging device 10 (to the left side in FIG. 1) by the first optical member M1 for bending the optical path by approximately 90 degrees. The light is deflected and incident on the second optical member M2, which is an optical path deflecting member, and the optical path is deflected approximately 90 degrees below the imaging device 10 (downward in the drawing of FIG. 1). The light beam deflected by the second optical member M2 enters and exits the relay front group 3 of the relay lens group, enters the third optical member M3, is deflected by approximately 90 degrees, and is behind the imaging device 10 (in FIG. 1). It is emitted in the right direction of the paper surface) and enters the rear relay group 4 of the relay lens group, and a secondary image is formed on the secondary imaging plane I2. In order to magnify and observe the secondary image formed on the secondary imaging plane I2 at the eye point EP, an eyepiece lens group including a pre-eyepiece group 5 having positive refractive power and a post-eyepiece group 6 having positive refractive power is arranged. Yes.

  The relay front group 3 includes a single lens L31 having a positive refractive power, a single lens L32 having a negative refractive power, and a single lens L33 having a positive refractive power in order from the object side along the optical axis. The group 4 includes a single lens L41 having a positive refractive power.

  The optical path of the light beam from the focusing screen I1 and the optical path of the light beam from the third optical member M3 intersect between the third optical member M3 and the relay rear group 4, and the light flux from the intersecting focusing screen I1. The relay rear group 4 is arranged at a position where it does not interfere.

  Further, the diopter adjustment of the relay type finder optical system M can be performed by moving the pre-eyepiece group 5 in the optical axis direction. Thus, the relay type finder optical system M according to the first embodiment of the present invention is configured.

  The relay type finder optical system M according to the first embodiment of the present invention divides a relay lens group into a relay front group 3 and a relay rear group 4, and focuses on an optical path between the relay front group 3 and the relay rear group 4. By arranging the optical paths of the light beams from the plate I1 so as to intersect, the position of the optical axis IP of the eyepiece lens group can be brought close to the position of the optical axis I11 of the photographing lens 11, and the finder window 14 and the liquid crystal monitor 16 Can be easily switched, and the relay finder optical system M can be downsized as a whole.

  In addition, by disposing the relay front group 3 between the second optical member M2 and the third optical member M3, the optical member does not protrude greatly from the focusing screen I1 to the object side (left direction in FIG. 2). Interference between the components of the relay type finder optical system M and the photographing lens 11 can be prevented.

  In the case of a digital single-lens reflex camera, a liquid crystal monitor 16 is arranged on the back of the camera for displaying captured images and displaying various information about the camera. By moving the position of the optical axis IP of the eyepiece lens closer to the position of the optical axis I11 of the photographing lens 11, the amount of eye movement for confirming the contents of the liquid crystal monitor 16 from the state of observation through the finder window 14 is small. Thus, the photographer can easily switch information.

  Further, since the relay rear group 4 is disposed in the vicinity of the second image plane I2 where the relay lens group forms a secondary image, the optical system composed of the relay rear group 4 and the eyepiece lens group is made more compact. can do. In addition, it is possible to satisfactorily set the pupil position of the relay lens group and the pupil position of the eyepiece lens group.

  Also, by configuring the relay front group 3 with only three lenses, the relay front group 3 can be configured in a compact manner, and there is a sufficient interval for arranging optical members for bending the optical path before and after the relay lens group. Therefore, a light shielding member (for example, an aperture stop) for blocking flare and ghost can be effectively arranged.

  In addition, by using only a single lens having a positive refractive power as the rear group 4, an optical system composed of the rear group 4 and the eyepiece group can be made compact. In addition, it is possible to satisfactorily set the positional relationship between the pupils and to reduce the overall size.

  Further, by performing diopter adjustment by moving the pre-eyepiece group 5 in the optical axis direction, the post-eyepiece group 6 which is the final lens group of the relay type finder optical system M can be fixed, and diopter adjustment is performed. Accordingly, it is possible to configure so that the change in the pupil position, that is, the position of the eye point EP does not change.

  Conventionally, when the last eyepiece group 6 which is the final lens group is operated for diopter adjustment, protective glass has been arranged to take dust-proof, drip-proof and waterproof structures, and up to the eye point for the provision of protective glass This shortened the distance and increased the cost of the protective glass. In the first embodiment, since the last eyepiece group 6 which is the final lens group is fixed, there is no need to arrange a protective glass for making a dustproof, dripproof and waterproof structure, and the distance to the eye point Is not shortened and the cost is reduced.

  In the first embodiment, the optical members M1, M2, and M3 are mirrors, but optical members such as prisms can also be used.

  The same effect can be obtained when the relay front group 3 is disposed between the focusing screen I1 and the first optical member M1, between the first optical member M1 and the second optical member M2, or immediately after the third optical member M3. Can be played.

(Second Embodiment)
FIG. 3 is a schematic configuration diagram of a relay type finder optical system M according to the second embodiment of the present invention. In the second embodiment, the first optical member M1 and the second optical member M2 of the first embodiment are configured by one optical member. The same components as those in the first embodiment will be described with the same reference numerals.

  In FIG. 3, the light beam from the focusing screen I1 on which the primary image of the imaging device 10 is formed enters the prism P1 for deflecting the optical path. The light beam from the focusing screen I1 is changed in direction by about 180 degrees with respect to the incident light side by the first reflecting surface R1 and the second reflecting surface R2 of the prism P1. The first reflecting surface R1 for bending the optical path of the light beam from the focusing screen I1 is deflected forward (to the left in FIG. 1) by the first reflecting surface R1, and the approximately 90 degree optical path is imaged by the second reflecting surface R2. It is deflected below the apparatus 10 (downward on the page of FIG. 1). The light beam emitted from the prism P1 enters and exits the relay front group 3 of the relay lens group, enters the third optical member M3, is deflected by approximately 90 degrees, and is rearward of the imaging device 10 (rightward direction in FIG. 1). And enters the rear relay group 4 of the relay lens group, and a secondary image is formed on the secondary imaging plane I2. In order to magnify and observe the secondary image formed on the secondary imaging plane I2 at the eye point EP, an eyepiece lens group including a pre-eyepiece group 5 having positive refractive power and a post-eyepiece group 6 having positive refractive power is arranged. Yes.

  The relay front group 3 includes a single lens L31 having a positive refractive power, a single lens L32 having a negative refractive power, and a single lens L33 having a positive refractive power in order from the object side along the optical axis. The rear group 4 includes a single lens L41 having a positive refractive power.

  The optical path of the light beam from the focusing screen I1 and the optical path of the light beam from the third optical member M3 intersect between the third optical member M3 and the relay rear group 4, and the light flux from the intersecting focusing screen I1. The relay rear group 4 is arranged at a position where it does not interfere.

  Further, the diopter adjustment of the relay type finder optical system M can be performed by moving the pre-eyepiece group 5 in the optical axis direction. Thus, the relay type finder optical system M according to the second embodiment of the present invention is configured.

    The relay type finder optical system M according to the second embodiment of the present invention divides a relay lens group into a relay front group 3 and a relay rear group 4, and focuses on an optical path between the relay front group 3 and the relay rear group 4. By arranging the optical paths of the light beams from the plate I1 so as to intersect, the position of the optical axis IP of the eyepiece lens group can be brought close to the position of the optical axis I11 of the photographing lens 11, and the finder window 14 and the liquid crystal monitor 16 Can be easily switched, and the relay type finder optical system M can be reduced in size as a whole.

  Further, the relay front group 3 is disposed between the prism P1 and the third optical member M3, so that the optical member does not protrude greatly from the focusing screen I1 to the object side (left direction in FIG. 2). It is also possible to prevent interference between the components of the optical system M and the taking lens 11.

  In the case of a digital single-lens reflex camera, a liquid crystal monitor 16 is arranged on the back of the camera for displaying captured images and displaying various information about the camera. By moving the position of the optical axis IP of the eyepiece lens closer to the position of the optical axis I11 of the photographing lens 11, the amount of eye movement for confirming the contents of the liquid crystal monitor 16 from the state of observation through the finder window 14 is small. Thus, the photographer can easily switch information.

  Further, since the relay rear group 4 is disposed in the vicinity of the second image plane I2 where the relay lens group forms a secondary image, the optical system composed of the relay rear group 4 and the eyepiece lens group is made more compact. can do. In addition, it is possible to satisfactorily set the pupil position of the relay lens group and the pupil position of the eyepiece lens group.

  Also, by configuring the relay front group 3 with only three lenses, the relay front group 3 can be configured in a compact manner, and there is a sufficient interval for arranging optical members for bending the optical path before and after the relay lens group. Therefore, a light shielding member (for example, an aperture stop) for blocking flare and ghost can be effectively arranged.

  In addition, by using only a single lens having a positive refractive power as the rear group 4, an optical system composed of the rear group 4 and the eyepiece group can be made compact. In addition, it is possible to satisfactorily set the positional relationship between the pupils and to reduce the overall size.

  Further, by bending the optical path from the focusing screen I1 with the prism P1, it becomes possible to prevent unnecessary rays from entering the relay front group 3, and flare and light when the photographer looks into the finder window 14 can be prevented. Ghost can be reduced.

  Further, by performing diopter adjustment by moving the pre-eyepiece group 5 in the optical axis direction, the post-eyepiece group 6 which is the final lens group of the relay type finder optical system M can be fixed, and diopter adjustment is performed. Accordingly, it is possible to configure so that the change in the pupil position, that is, the position of the eye point EP does not change.

  Conventionally, when the rear lens group 6 which is the final lens group is operated for diopter adjustment, a protective glass is arranged to take a dustproof, dripproof and waterproof structure. The distance to the front was shortened and the cost for the protective glass was increased. In the second embodiment, since the rear lens group 6 as the final lens group is fixed, it is not necessary to arrange a protective glass for making a dust-proof, drip-proof, and waterproof structure. The distance is not shortened and the cost is reduced.

  In the second embodiment, a mirror is used as the optical member M3, but an optical member such as a prism may be used.

  Further, the same effect can be obtained even if the relay front group 3 is disposed between the focusing screen I1 and the prism P1 or immediately after the third optical member M3.

(Third embodiment)
FIG. 4 is a schematic configuration diagram of a relay type finder optical system M according to a third embodiment of the present invention.
In FIG. 4, the light beam from the focusing screen I1 that forms the primary image of the image pickup apparatus 10 is deflected forward (to the left in FIG. 1) of the image pickup apparatus 10 by the first optical member M1 for bending the optical path by approximately 90 degrees. Then, the light is incident on the second optical member M2 which is an optical path deflecting member, and the optical path is deflected below the imaging device 10 (downward in the drawing in FIG. 1) by about 90 degrees. The light beam deflected by the second optical member M2 enters and exits the relay front group 3 of the relay lens group, enters the prism P3 for bending the optical path, is deflected by approximately 90 degrees, and is behind the imaging device 10 (see FIG. 1 in the right direction of the drawing sheet 1) and enters the rear relay group 4 of the relay lens group, and a secondary image is formed on the secondary imaging plane I2. In order to magnify and observe the secondary image formed on the secondary imaging plane I2 at the eye point EP, an eyepiece lens group including a pre-eyepiece group 5 having positive refractive power and a post-eyepiece group 6 having positive refractive power is arranged. Yes.

  The relay front group 3 includes a single lens L31 having a positive refractive power, a single lens L32 having a negative refractive power, and a single lens L33 having a positive refractive power in order from the object side along the optical axis. The rear group 4 includes a single lens L41 having a positive refractive power.

  The optical path of the light beam from the focusing screen I1 and the optical path of the light beam from the prism P3 intersect between the prism P3 and the relay rear group 4, and after relaying to a position where they do not interfere with the light flux from the intersecting focusing screen I1. Group 4 is arranged.

  Further, the diopter adjustment of the relay type finder optical system M can be performed by moving the pre-eyepiece group 5 in the optical axis direction. Thus, the relay type finder optical system M according to the third embodiment of the present invention is configured.

    The relay type finder optical system M according to the third embodiment of the present invention divides a relay lens group into a relay front group 3 and a relay rear group 4, and focuses on an optical path between the relay front group 3 and the relay rear group 4. By arranging the optical paths of the light beams from the plate I1 so as to intersect, the position of the optical axis IP of the eyepiece lens group can be brought close to the position of the optical axis I11 of the photographing lens 11, and the finder window 14 and the liquid crystal monitor 16 Can be easily switched, and the relay type finder optical system M can be reduced in size as a whole.

  Further, the relay front group 3 is disposed between the second optical member M2 and the prism P3, so that the optical member does not protrude greatly from the focusing screen I1 to the object side (leftward direction in FIG. 2). It is also possible to prevent interference between the components of the optical system M and the taking lens 11.

  In the case of a digital single-lens reflex camera, a liquid crystal monitor 16 is arranged on the back of the camera for displaying captured images and displaying various information about the camera. By moving the position of the optical axis IP of the eyepiece lens closer to the position of the optical axis I11 of the photographing lens 11, the amount of eye movement for confirming the contents of the liquid crystal monitor 16 from the state of observation through the finder window 14 is small. Thus, the photographer can easily switch information.

  Further, since the relay rear group 4 is disposed in the vicinity of the second image plane I2 of the relay lens group, the optical system including the relay rear group 4 and the eyepiece lens group can be configured more compactly. In addition, it is possible to satisfactorily set the pupil position of the relay lens group and the pupil position of the eyepiece lens group.

  Also, by configuring the relay front group 3 with only three lenses, the relay front group 3 can be configured in a compact manner, and there is a sufficient interval for arranging optical members for bending the optical path before and after the relay lens group. Therefore, a light shielding member (for example, an aperture stop) for blocking flare and ghost can be effectively arranged.

  In addition, by using only a single lens having a positive refractive power as the rear group 4, an optical system composed of the rear group 4 and the eyepiece group can be made compact. In addition, it is possible to satisfactorily set the positional relationship between the pupils and to reduce the overall size.

  Further, since the light beam from the relay front group 3 is deflected in the optical path by the prism P3, unnecessary light from the focusing screen I1 can be prevented from directly entering the relay front group 3 of the relay lens group. Thus, flare and ghost when looking through the finder 14 of the imaging apparatus 10 can be reduced.

  Further, by performing diopter adjustment by moving the pre-eyepiece group 5 in the optical axis direction, the post-eyepiece group 6 which is the final lens group of the relay type finder optical system M can be fixed, and diopter adjustment is performed. Accordingly, it is possible to configure so that the change in the pupil position, that is, the position of the eye point EP does not change.

  Conventionally, when the rear lens group 6 which is the final lens group is operated for diopter adjustment, a protective glass is arranged to take a dustproof, dripproof and waterproof structure. The distance to the front was shortened and the cost for the protective glass was increased. In the third embodiment, since the last eyepiece group 6 which is the final lens group is fixed, there is no need to arrange a protective glass for making a dustproof, dripproof and waterproof structure, and the eyepoint EP can be reduced. The distance is not shortened and the cost is reduced.

  In the third embodiment, the optical members M1 and M2 are mirrors, but optical members such as prisms may be used.

  Further, the same effect can be obtained even if the relay front group 3 is arranged between the focusing screen I1 and the first optical member M1, between the first optical member M1 and the second optical member M2, or immediately after the prism P3. Can do.

(Fourth embodiment)
FIG. 5 is a schematic configuration diagram of a relay type finder optical system M according to a fourth embodiment of the present invention.
In FIG. 5, the light beam from the focusing screen I1 that forms the primary image of the image pickup apparatus 10 is deflected forward of the image pickup apparatus 10 (left side in FIG. 1) by the first optical member M1 for bending the optical path by approximately 90 degrees. Then, the light is incident on the second optical member M2 which is an optical path deflecting member, and the optical path is deflected below the imaging device 10 (downward in the drawing in FIG. 1) by about 90 degrees. The light beam deflected by the second optical member M2 enters and exits the relay front group 3 of the relay lens group, enters the third optical member M3, is deflected by approximately 90 degrees, and is behind the imaging device 10 (in FIG. 1). It is emitted in the right direction of the paper surface) and enters the rear relay group 4 of the relay lens group, and a secondary image is formed on the secondary imaging plane I2. In order to magnify and observe the secondary image formed on the secondary imaging plane I2 at the eye point EP, an eyepiece lens group including a pre-eyepiece group 5 having positive refractive power and a post-eyepiece group 6 having positive refractive power is arranged. Yes.

  The relay front group 3 includes a single lens L31 having a positive refractive power, a single lens L32 having a negative refractive power, and a single lens L33 having a positive refractive power in order from the object side along the optical axis. The rear group 4 includes a single lens L41 having a positive refractive power.

  The optical path of the light beam from the focusing screen I1 and the optical path of the light beam from the third optical member M3 intersect between the third optical member M3 and the relay rear group 4, and the light flux from the intersecting focusing screen I1. The relay rear group 4 is arranged at a position where it does not interfere.

  Further, the diopter adjustment of the relay type finder optical system M can be performed by moving the pre-eyepiece group 5 in the optical axis direction.

  The optical member M1 is formed of a half mirror, the light beam reflected by the optical member M1 travels in the direction of the optical member M2, and the light beam transmitted through the optical member M1 is an optical member M4 disposed above the optical member M1. The light intensity from a subject (not shown) reflected, condensed by the photometric optical system 7 on the photometric device 8 and incident on the photographing lens 11 is measured. Thus, the relay type finder optical system M according to the fourth embodiment of the present invention is configured.

    The relay type finder optical system M according to the fourth embodiment of the present invention divides a relay lens group into a relay front group 3 and a relay rear group 4, and focuses on an optical path between the relay front group 3 and the relay rear group 4. By arranging the optical paths of the light beams from the plate I1 so as to intersect, the position of the optical axis IP of the eyepiece lens group can be brought close to the position of the optical axis I11 of the photographing lens 11, and the finder window 14 and the liquid crystal monitor 16 Can be easily switched, and the relay type finder optical system M can be reduced in size as a whole.

  In addition, by disposing the relay front group 3 between the second optical member M2 and the third optical member M3, the optical member does not protrude greatly from the focusing screen I1 to the object side (left direction in FIG. 2). Interference between the components of the relay type finder optical system M and the photographing lens 11 can be prevented.

  In the case of a digital single-lens reflex camera, a liquid crystal monitor 16 is arranged on the back of the camera for displaying captured images and displaying various information about the camera. By moving the position of the optical axis IP of the eyepiece lens closer to the position of the optical axis I11 of the photographing lens 11, the amount of eye movement for confirming the contents of the liquid crystal monitor 16 from the state of observation through the finder window 14 is small. Thus, the photographer can easily switch information.

  Further, since the relay rear group 4 is disposed in the vicinity of the second image plane I2 of the relay lens group, the optical system including the relay rear group 4 and the eyepiece lens group can be configured more compactly. In addition, it is possible to satisfactorily set the pupil position of the relay lens group and the pupil position of the eyepiece lens group.

  Also, by configuring the relay front group 3 with only three lenses, the relay front group 3 can be configured in a compact manner, and there is a sufficient interval for arranging optical members for bending the optical path before and after the relay lens group. Therefore, a light shielding member (for example, an aperture stop) for blocking flare and ghost can be effectively arranged.

  In addition, by using only a single lens having a positive refractive power as the rear group 4, an optical system composed of the rear group 4 and the eyepiece group can be made compact. In addition, it is possible to satisfactorily set the positional relationship between the pupils and to reduce the overall size.

  Further, by performing diopter adjustment by moving the pre-eyepiece group 5 in the optical axis direction, the post-eyepiece group 6 which is the final lens group of the relay type finder optical system M can be fixed, and diopter adjustment is performed. Accordingly, it is possible to configure so that the change in the pupil position, that is, the position of the eye point EP does not change.

  Conventionally, when the rear lens group 6 which is the final lens group is operated for diopter adjustment, a protective glass is arranged to take a dustproof, dripproof and waterproof structure. The distance to the front was shortened and the cost for the protective glass was increased. In the fourth embodiment, since the last eyepiece group 6 which is the final lens group is fixed, it is not necessary to arrange a protective glass for providing a dustproof, dripproof, and waterproof structure. The distance is not shortened and the cost is reduced.

  Further, since the optical member M1 is formed of a half mirror, the light beam reflected by the optical member M1 travels in the direction of the optical member M2, and the light beam transmitted through the optical member M1 is an optical element disposed above the optical member M1. It is possible to measure the light intensity from a subject (not shown) reflected by the member M4, condensed by the photometric optical system 7 on the photometric device 8 and incident on the photographing lens 11. With such a configuration, it is possible to divide the optical path of the reflected light of the optical member M1 in the direction of the relay lens group and the transmitted light to the photometric optical system 7. As a result, the photometric optical system 7 can measure the focusing screen I1 from the front, and it is not necessary to perform measurement from an angle as in the case of a conventional finder photometric system using a pentaprism, thereby improving photometric accuracy. Is possible.

  In the fourth embodiment, the optical members M2, M3, and M4 are mirrors, but optical members such as prisms can also be used.

  The same effect can be obtained when the relay front group 3 is disposed between the focusing screen I1 and the first optical member M1, between the first optical member M1 and the second optical member M2, or immediately after the third optical member M3. Can be played.

  In all the embodiments, one aspheric lens can be arranged in the relay lens group. By using one aspherical surface for the relay lens group on the object side surface, it becomes possible to correct spherical aberration well, and performance can be achieved even if the pupil position with the eyepiece lens group is adjusted with other lenses. Can be maintained. When one aspherical surface is used at a position close to the eyepiece lens group, the spherical aberration is corrected with the other lens, and the coma aberration is adjusted while adjusting the pupil position with the eyepiece lens group with the aspherical lens. Can be corrected satisfactorily.

  In all the embodiments, a plastic lens can be used as at least one of the relay lens group and the eyepiece lens group. Thus, it becomes possible to further reduce the price and weight by using the plastic lens.

  Further, in all the embodiments, the front lens group 3 may be divided into a plurality of lenses and a part of the lens groups divided between the focusing screen I1 and the rear relay group 4 may be arranged.

  In all the embodiments, a lens system having a two-group configuration is shown. However, a lens system in which an additional lens group is added to the two groups is also an equivalent lens system having the effect of the present invention. Needless to say. In addition, in the configuration within each lens group, it goes without saying that a lens group in which an additional lens is added to the configuration of the embodiment is an equivalent lens group in which the effects of the present invention are inherent.

  Further, the above-described embodiment is merely an example, and is not limited to the above-described configuration or shape, and can be appropriately modified and changed within the scope of the present invention.

  According to the present invention, there is provided a small relay type finder optical system that can be used mainly as a digital still camera or a finder for a single-lens reflex camera, can bring the finder optical axis close to the optical axis of the photographing lens. It becomes possible. Further, it becomes possible to provide a camera having this relay type finder optical system.

It is a schematic block diagram of the imaging device concerning this invention which has a relay type finder optical system concerning this invention. It is a schematic block diagram of the relay type finder optical system concerning 1st Embodiment of this invention. It is a schematic block diagram of the relay type finder optical system concerning 2nd Embodiment of this invention. It is a schematic block diagram of the relay type finder optical system concerning 3rd Embodiment of this invention. It is a schematic block diagram of the relay type finder optical system concerning 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Relay front group 4 Relay back group 5 Pre-eyepiece group 6 Post-eyepiece group 7 Photometry optical system 8 Photometry apparatus 10 Imaging apparatus 11 Shooting lens 12 Quick return mirror 14 Viewfinder window 15 Imaging element 16 Liquid crystal monitor I1 Focus plate I2 Second imaging Surface M1 First optical member M2 Second optical member M3 Third optical member P1, P3 Prism EP Eye point

Claims (7)

A relay lens group having a positive refractive power for forming a secondary image from a primary image in order from the object side along the optical axis, and an eyepiece group having a positive refractive power for observing the secondary image Have
The relay lens group consists of a relay front group and a relay rear group in order from the object side along the optical axis,
A relay type finder optical system comprising optical means for crossing an optical path from the primary image in an optical path between the relay front group and the relay rear group. The secondary image is formed between the relay lens group and the eyepiece group,
The relay finder optical system according to claim 1, wherein the relay rear group is disposed in the vicinity of the secondary image. The relay front group is composed of a single lens having a positive refractive power, a single lens having a negative refractive power, and a single lens having a positive refractive power in order from the object side along the optical axis.
3. The relay type finder optical system according to claim 1, wherein the relay rear group includes only a single lens having a positive refractive power. The eyepiece lens group is composed of, in order from the object side along the optical axis, a front eyepiece group having positive refractive power and a rear eyepiece group having positive refractive power,
4. The relay type finder optical system according to claim 1, wherein diopter adjustment is performed by moving the pre-eyepiece group in an optical axis direction. 5.   The relay type finder optical system according to any one of claims 1 to 4, wherein the relay lens group includes one aspherical lens.   6. The relay type finder optical system according to claim 1, wherein at least one of the relay lens group and the eyepiece lens group is made of a plastic lens.   An imaging apparatus comprising the relay type finder optical system according to claim 1.

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