JP2000147603A - Single-lens reflex type camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily arrange a relay optical system for relaying an image on a focusing screen to an ocular optical system by providing a reflection optical path having plural reflection surfaces and arranging the relay optical system for relaying the image formed on a primary image-formation surface equivalent to the image pickup surface of an imaging device in the reflection optical path to the ocular optical system. SOLUTION: An ocular optical system 30 is arranged above a photographing optical system 10. Meanwhile, a light division surface 11a of a beam splitter 11 is set in a direction, where the reflection optical path (reflection optical axis) 13 of subject luminous flux reflected by the surface 11a pointed downward, nearly opposite to the optical system 30 differently from the conventional single lens reflex camera. Thus, by constituting the reflection optical path for guiding the subject luminous flux to the optical system 30 on a plane orthogonal to an optical axis 10X around the optical system 10, after turning the reflecting direction of the subject luminous flux by the surface 11a of the beam splitter 11 downward (nearly opposite side to a side where the optical system 30 exists), the space where the optical system 20 is arranged is easily secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-lens reflex camera, and more particularly to an arrangement of a finder optical system.

[0002]

2. Description of the Related Art Conventionally, as a single-lens reflex camera provided with a reflecting member in a photographing optical path for reflecting a light beam of a subject transmitted through a photographing optical system toward a finder optical system, an image sensor is conventionally provided on an image forming surface of the photographing optical system. A placed digital still camera is known. Any of a quick return mirror, a quick return half mirror, and a fixed half mirror (beam splitter) can be used as the reflection member in the imaging optical path. The biggest difference between a digital still single-lens reflex camera and a single-lens reflex camera using, for example, a Leica silver halide film is that the imaging surface of an image sensor is generally smaller than a photographic screen of a silver halide film camera. Narrow).

In a camera using a small-sized image sensor, an image can be formed on a small image-capturing surface. However, if the photographing optical system in the single-lens reflex camera becomes very small, it becomes difficult to configure the finder optical system. That is, the light beam transmitted through the photographing optical system is simply branched for the finder optical system,
When a primary imaging plane is formed at a position (focus plate) equivalent to the imaging device, the size of the primary imaging surface becomes the same size as the imaging surface of the imaging device. It is difficult to observe an image of such a small primary imaging plane as an erect erect image with the configuration of the finder optical system of the conventional single-lens reflex camera. Therefore,
A relay optical system that enlarges the image on the primary image plane and forms an image on the secondary image plane is indispensable, but this relay optical system requires at least several lenses in consideration of image performance. I do.

However, in the viewfinder optical system of the conventional single-lens reflex camera, the direction of reflection of the subject light beam by the reflecting member in the photographing optical path is generally set to the direction facing the eyepiece optical system of the viewfinder optical system. That is, the finder optical path from the reflecting member to the eyepiece optical system is determined to be almost the shortest optical path, and it is difficult to take up space for disposing the above-described relay optical system. Alternatively, the size of the camera increases due to the arrangement of the relay optical system.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a single-lens reflex camera having a reflecting member in a photographing optical path, in which a relay optical system for relaying an image on a focus plate to an eyepiece optical system can be easily arranged. I do.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a single lens having a reflection member in a photographing optical path for reflecting a subject light beam transmitted through a photographing optical system toward a finder optical system, and an image pickup device placed on an imaging plane of the photographing optical system. In a reflex camera, the direction in which the reflecting member in the shooting optical path reflects the subject light beam is set to a direction substantially opposite to the eyepiece optical system of the finder optical system, and the light is reflected by the reflecting member in the shooting optical path around the shooting optical system. A reflection optical path having a plurality of reflection surfaces for guiding the subject light beam to the eyepiece optical system, and relaying an image formed on a primary imaging surface equivalent to the imaging surface of the image sensor to the eyepiece optical system in the reflection light path. The relay optical system is arranged.

The relay optical system is an enlargement optical system that enlarges an image formed on a primary image forming surface equivalent to an image pickup surface of an image pickup device and re-images the image.

[0008]

1 and 2 are conceptual views showing an embodiment in which the present invention is applied to a digital still camera using a single-lens reflex camera. In this embodiment, a fixed beam splitter (fixed half mirror) is used as a reflecting member in a photographing optical path.
This is an example using. The luminous flux transmitted through the photographing optical system 10 is
The light enters a beam splitter (half mirror) 11 fixed to an observation position in the imaging optical path, and is incident on the beam splitter 11.
The light flux transmitted through the light splitting surface (reflection surface) 11a of the image pickup device 12 is placed on the image forming surface (focal surface) of the photographing optical system 10.
Incident on. The imaging optical system 10 forms a subject image directly on the imaging surface of the imaging element 12.

Above the photographing optical system 10, the eyepiece optical system 3
0 is arranged. On the other hand, unlike the conventional single-lens reflex camera, the light splitting surface 11a of the beam splitter 11 directs the reflection optical path (reflection optical axis) 13 of the subject light flux reflected by the light splitting surface 11a downward substantially opposite to the eyepiece optical system 30. Direction is set.

A primary imaging plane 14 equivalent to the imaging plane of the imaging device 12 is located on the reflection optical path 13.
A condenser lens 15 is provided in the vicinity of the back of the lens 4. Below the beam splitter 11, a pentaprism 16 having two reflection surfaces 16a and 16b forming 45 ° each other is disposed as a lower reflector for bending the reflection optical path 13 to the side of 90 °. A reflecting member 18 is disposed on the side as a lower side reflector that bends the side reflected light path 17 further upward by 90 ° to make it substantially vertical. A relay optical system 20 is disposed in the vertical reflection optical path 19 bent by the reflection member 18, and at the intersection of the vertical reflection optical path 19 and the optical axis 30 </ b> X of the eyepiece optical system 30, as an upper reflector, 45 ° from each other. A pentaprism 22 having two reflecting surfaces 22a and 22b is disposed. The pentaprism 22 bends the vertical reflection optical path 19 by 90 ° so as to coincide with the optical axis 30X of the eyepiece optical system 30.

As described above, the direction of reflection of the subject light beam by the light splitting surface 11a of the beam splitter 11 is directed downward (substantially opposite to the side where the eyepiece optical system 30 exists), and By configuring a reflected light path for guiding the subject light beam to the eyepiece optical system 30 in a plane orthogonal to the optical axis 10X, the arrangement space for the relay optical system 20 can be easily secured. That is, even if the number of constituent lenses of the relay optical system 20 is increased in order to improve the image performance, it can be easily dealt with.

The subject image formed on the primary imaging surface 14 equivalent to the imaging surface of the imaging device 12 is
Thus, a suitably enlarged secondary image is formed on the secondary imaging plane 21, and this secondary image is enlarged and observed through the eyepiece optical system 30. That is, both the relay optical system 20 and the eyepiece optical system 30 are magnifying optical systems. In addition, the optical path from the photographing optical system 10 to the eyepiece optical system 30 including the light splitting surface 11a of the beam splitter 11 has an appropriate number of six surfaces for making an image observed by the eyepiece optical system 30 an erect image. Reflective surfaces in different directions. In the embodiment of FIG.
The reflecting surfaces 16a and 16b of the pentaprism 16 can be replaced with mirrors.

FIGS. 3 and 4 show a second embodiment of the present invention. This embodiment uses a mirror 41 instead of the pentaprism 16 of the first embodiment, and
This is an embodiment in which a pentagonal roof prism 42 is used instead. The pentagonal roof prism 42 has a pair of roof reflecting surfaces 42a and 42b orthogonal to each other, and a third reflecting surface 42c that forms 45 ° with the ridge line of the roof reflecting surfaces 42a and 42b. Also in this embodiment, a total of six reflecting surfaces for securing an image observed by the eyepiece optical system 30 as an erect image are secured in the optical path from the imaging optical system 10 to the eyepiece optical system 30.

In this embodiment, the subject image formed on the primary imaging plane 14 is enlarged and formed on the secondary imaging plane 21 via the relay optical system 20, as in the first embodiment. This image is enlarged and observed via the eyepiece optical system 30.

[0015]

According to the present invention, in a single-lens reflex camera, a relay optical system for relaying an image formed on a primary imaging plane equivalent to an imaging plane of an imaging element to an eyepiece optical system can be easily arranged. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a single-lens reflex digital still camera according to the present invention.

FIG. 2 is a development view of elements ranging from a reflection member in a photographing optical path of the camera of FIG. 1 to an eyepiece optical system.

FIG. 3 is a perspective view showing another embodiment of the single-lens reflex digital still camera according to the present invention.

FIG. 4 is a development view of elements ranging from a reflection member in a photographing optical path of the camera of FIG. 3 to an eyepiece optical system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Imaging optical system 10X Optical axis of imaging optical system 11 Beam splitter (reflection member in imaging optical path) 11a Light splitting surface (reflection surface) 12 Image sensor 13 Reflection optical path 14 Primary imaging surface 15 Condenser lens 20 Relay optical system 21 Secondary Image plane 30 Eyepiece optical system 30X Optical axis of photographing optical system

Claims (2)

[Claims] A reflection member in a photographing optical path for reflecting a subject light beam transmitted through the photographing optical system toward a finder optical system;
In a single-lens reflex camera having an image pickup device placed on an imaging surface of a photographic optical system, the direction in which the reflecting member in the photographic optical path reflects a subject light beam is substantially opposite to the direction of the eyepiece optical system of the finder optical system. A reflection optical path having a plurality of reflection surfaces is formed around the imaging optical system to guide the subject light beam reflected by the reflection member in the imaging optical path to the eyepiece optical system, and an image sensor is provided in the reflection optical path. A single-lens reflex camera, comprising a relay optical system for relaying an image formed on a primary imaging plane equivalent to the imaging plane of the above to an eyepiece optical system. 2. The single-lens reflex camera according to claim 1, wherein the relay optical system is a magnifying optical system that magnifies and re-images an image formed on a primary imaging surface equivalent to an imaging surface of an imaging device. A single-lens reflex camera.