JP2003307764A - Viewfinder optical system for single-lens reflex camera - Google Patents

Abstract

(57) [Problem] To provide a viewfinder optical system of a single-lens reflex camera which observes a subject image with both eyes of a photographer, reduces eye fatigue and facilitates focusing. SOLUTION: A focus glass 31 for forming a subject image.
A roof mirror 32, a pellicle mirror 33, for magnifying and observing a subject image formed on a focus glass 31;
In the viewfinder optical system of the single-lens reflex camera including the view lens 34, the effective aperture (viewpoint) 3 of the view lens 34
The dimension of 4A is a dimension that allows the subject's image on the focus glass to be simultaneously visible to both eyes of the photographer, for example, a dimension substantially equal to the interpupillary dimension of both eyes of the photographer. The photographer can observe the subject image formed on the focusing glass 31 with both eyes, and can stereoscopically view the subject image, which reduces the fatigue when observing the subject image and facilitates focusing. It is possible to perform a proper shooting.

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 a viewfinder of a single-lens reflex camera which reduces eye fatigue of a photographer when observing a subject image on a focus glass and makes it easy to observe the subject image. It relates to an optical system.

[0002]

2. Description of the Related Art As a standard viewfinder optical system for a single-lens reflex camera, as shown in the schematic view of FIG. 7, the light imaged by a taking lens 102 is reflected by a quick return mirror 107 in a camera body 101. A subject image that is upside down on a focus glass 103 installed at a position equivalent to the film surface, and the formed subject image is converted into an erect image by a pentagonal roof prism 104, and the erect image is a view lens. (Eyepiece) 105 is used to magnify and observe. In this viewfinder optical system, in order for the photographer to visually observe the erect image magnified by the view lens 105 and confirm the focusing state, the photographer needs to use an effective aperture (here, the viewing aperture) on the eyepiece side of the view lens 105. It is necessary to look into the finder with one eye E in close proximity.

[0003]

As described above, in the viewfinder optical system of the conventional single-lens reflex camera, the view lens 1 is used.
Since it is necessary to bring one of the eyes E of the photographer close to the mouth of 05 and observe the subject image with the one eye, there is a problem that the eyes of the photographer are easily tired. In addition, a finder (sometimes referred to as an action finder) capable of observing a subject image with the photographer's eyes separated from the view lens 105 has been proposed, which results in a long eye relief of the view lens. Although it is designed, even in this case, the size of the effective opening of the mouth is smaller than the width of both eyes of the photographer, and as a result, it will be observed with one eye, so it is not possible to improve eye fatigue. Not in. Also, when observing the subject image with one eye through the view lens, it is difficult to confirm the focus state in the depth direction of the subject image,
There is also a problem that it is difficult to focus easily.

An object of the present invention is to provide a viewfinder optical system for a single-lens reflex camera that enables a photographer to observe a subject image with both eyes, reduces eye fatigue, and facilitates focusing. It is provided.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a single-lens reflex camera including a focus glass for forming a subject image and a view lens for magnifying and observing the subject image formed on the focus glass. In the finder optical system, the effective aperture of the view lens is characterized in that it is formed in such a size that the subject image on the focus glass can be viewed simultaneously by both eyes of the photographer. For example, it is preferable that the effective aperture of the view lens be approximately equal to the interpupillary dimension of both eyes of the photographer.

Further, in the present invention, between the focus glass and the view lens, a roof mirror or roof prism for inverting the right and left of the subject image formed on the focus glass, and for inverting the top and bottom of the subject image. And a half mirror. In this case, it is preferable that the half mirror is a pellicle mirror. In addition, the focus glass has a light diffusing property in which the intensity of the incident light passing through the focus glass in a straight direction is set to be larger than the intensity of the light passing in a direction having a predetermined angle with respect to the straight direction at a constant rate. It is preferable that the structure has characteristics.

According to the present invention, the photographer can observe the subject image formed on the focus glass through the view lens with both eyes, and in that case, the adjustment and convergence of the eyes in each of the left and right eyes can be observed. It is possible to achieve a stereoscopic view of the subject image by balancing the visual fields of the left and right eyes. As a result, it is possible to perform shooting with less fatigue when observing a subject image with the finder optical system and with easy focusing.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a single-lens reflex camera equipped with a finder optical system according to the present invention as viewed from the back side. This is an example configured as a single-lens reflex camera using a 35 mm film.
The camera body 1 comprises a detachable interchangeable taking lens 2 on the front surface thereof, and the finder optical system 3 which is a feature of the present invention is disposed on the upper surface of the camera body 1. Here, the view lens 34 is provided in the finder optical system 3 as described later, and the effective aperture on the eyepiece side of the view lens, that is, the aperture size of the opening 34A, will be described in detail later, but the camera body The opening size in the horizontal direction on the back surface of No. 1 is set to be extremely large as compared with the conventional camera for observing with one eye. Further, the figure shows a release button 4 provided on the camera body 1, various switches 5 including a power switch, a display 6 made of liquid crystal, and the like, but a detailed description thereof will be given. Omit it.

FIG. 2 shows the single-lens reflex camera as a photographing lens 2
FIG. 3 is a schematic vertical sectional view cut along the optical axis of FIG. Inside the camera body 1, a mirror box 7 having a quick return mirror 71 on the optical axis of the taking lens 2 is arranged, and behind the mirror box 7 is a 35 mm film aperture 8 and a shutter mechanism 9. . Further, a focus glass 31, a roof mirror 32, and a pellicle mirror 33, which form a part of the finder optical system 3, are arranged above the mirror box 7, and the view lens 34 is provided behind the pellicle mirror 33. It is arranged.

FIG. 3 is an exploded perspective view of the finder optical system 3, and FIG. 4 is an equivalent plan view of the finder optical system 3 extended along the optical path. The focus glass 31 is composed of a semi-transparent plate having a rectangular shape slightly larger than the vertical and horizontal dimensions of the aperture 8 of the 35 mm film as before, and is imaged by the taking lens 2 to form a quick return mirror 71.
It is possible to form an image of the light reflected from the subject and visually observe the formed subject image. Here, the optical axis in the finder optical system 3 until the light reflected by the quick return mirror 71 reaches the view lens 34 is referred to as a finder optical axis FO. The pellicle mirror 33 is composed of a half mirror having a lateral width dimension slightly larger than the lateral width dimension of the focus glass 31, and in a position directly above the focus glass 31 in a direction perpendicular to the finder optical axis FO. It is arranged with its front facing upward at an angle of 45 degrees. The roof mirror 32 is disposed in front of the pellicle mirror 33, and is configured as two mirrors whose reflecting surfaces intersect each other at an angle of 90 degrees when viewed in a plane direction.

In order to magnify the subject image formed on the pink glass 31, the view lens 34 is formed as a convex lens having a required focal length in which a convex lens 34a and a concave lens 34b are bonded together. . The effective aperture of the view lens 34 is determined by a finder frame (not shown) provided on the back surface of the camera body 1. Here, the effective aperture is a dimension sufficiently long in the horizontal direction as described above. In order to have a laterally long binocular magnifying lens that has a length of about 7 cm, which is close to the width of the eyes of the human eye, and is longer than 1 cm, which is somewhat larger than the pupil diameter of the human eye in the vertical direction. It is configured. Further, the view lens 34 has a longer eye relief than that of a conventional action finder, and as shown in FIG. 2, the focus glass 31 is placed with the eye E of the photographer away from the back surface of the view lens 34. It is possible to observe the subject image above in an enlarged state. For the view lens 34, for example, it is possible to adopt the configuration of the binocular magnifying glass described in JP-A-6-95011. The binocular magnifying glass described in the same publication balances the adjustment and convergence of the eyes in each of the left and right eyes, balances the visual fields of the left and right eyes, and enables binocular vision in a reasonably natural state.

Further, the focus glass 31 has a required light diffusion characteristic, and as shown in an enlarged view of a region corresponding to a portion A in FIG. 4, the focus glass 31 and the finder optical axis FO are separated from each other. An optical axis connecting the right eye RE and the left eye LE of the photographer from the intersection, respectively, to be precise, an optical axis connecting the centers of the pupils of both eyes RE and LE is defined as the right eye optical axis RFO and the left eye optical axis LFO. In this case, focus glass 3 toward the optical axis of one eye.
The light diffusion characteristic is such that the ratio of the intensity of light emitted from 1 to the intensity of light emitted toward the optical axis of the other eye is 2: 1. For example, in the case of FIG. 5, the right eye R
When the light passing through the focus glass 31 toward E is diffused by the focus glass 31, the light intensity of the light emitted toward the right eye optical axis RFO is emitted toward the left eye optical axis LFO. The light intensity is set to be twice as high.

According to the single-lens reflex camera equipped with the finder optical system 3 having the above-described structure, the light from the subject imaged by the taking lens 2 is reflected by the quick return mirror 71 and left-right inverted on the focus glass 31. The image is formed as an inverted subject image. Further, the image-forming light passes through the focus glass 31, is then reflected forward by the pellicle mirror 33 at an angle of 90 degrees to be an erect image, and is reflected by the roof mirror 32. Since the roof mirror 32 is formed as two mirrors that intersect at an angle of 90 degrees,
The light reflected by the roof mirror 32 is rotated in the left-right direction,
Further, the view lens 34 is transmitted through the pellicle mirror 33.
Is incident on. Therefore, the photographer is
This makes it possible to observe the subject image on the pink glass 31 as an upright image with left and right reversed.

At this time, the left and right eyes RE and L of the photographer are emitted from one point of the subject image on the focus glass 31.
Considering the light incident on E, for example, referring to FIG. 4 and FIG. 5, from one point of the subject image formed by the right side light flux of the open light flux of the taking lens, which is divided into right and left, from the right eye optical axis When considering the light directed to the RFO, due to the above-mentioned light diffusion characteristic in the focus glass 31, the right eye optical axis RFO
The intensity of light incident on the right eye RE along the
It is about twice the intensity of the light directed to the FO. Similarly, although not shown, when considering light directed to the left-eye optical axis LFO from one point of the subject image formed by the left-side light flux of the open light flux of the taking lens, the left-side light flux is left. The intensity of the light incident on the left eye LE along the optical axis LFO of the eye is approximately twice the intensity of the light directed to the optical axis RFO of the right eye. With this, when the photographer observes the subject image with both eyes RE and LE, the subject image with the right pupil of the photographing lens is observed in the right eye, and the subject image with the left pupil of the photographing lens is observed in the left eye. Images viewed from different positions can be obtained for the left and right eyes, respectively, and the subject image can be stereoscopically viewed. Further, by setting the eye relief of the view lens 34 to be long, the photographer can perform observation with both eyes separated from the view lens 34. This makes it possible to perform shooting with less fatigue and easy focusing.

Further, in this embodiment, since the pellicle mirror 33 and the roof mirror 32 are used in the finder optical system 3, the weight and size can be reduced as compared with the conventional finder optical system using the pentagonal roof prism. . Therefore, even if a lens having a large effective aperture is used as the view lens 34, the weight of the entire finder optical system 3 does not increase and the size of the viewfinder optical system 3 does not increase. It should be noted that the dimension of the effective aperture of the view lens 34 is preferably set to be about the interpupillary dimension of both eyes in order to optimize the stereoscopic view by the finder optical system. Can also be smaller than the interpupillary dimension of both eyes.

When it is not required to downsize the finder optical system, a pentagonal roof mirror composed of a roof mirror 32 and a mirror 35 can be used as shown in FIG. 6 (a). Further, in the case where the finder optical system is not particularly required to be lightweight, a conventional pentagonal roof prism as shown in FIG. 7 may be used,
Alternatively, a plurality of prisms 36 as shown in FIG.
It is also possible to use a prism in which 37 are combined. In any case, by designing the aperture size width of the view lens 34 to be large, stereoscopic viewing with both eyes is possible,
Moreover, it is possible to configure a viewfinder optical system of a single-lens reflex camera with less fatigue and easy focusing.

In the above embodiment, an example in which the finder optical system according to the present invention is integrally incorporated in the camera body of a single-lens reflex camera has been described. However, the finder optical system is detachable from the camera body. Possible configuration,
It is also possible to configure as a single-lens reflex camera that can be replaced with a finder optical system that observes a subject image with one eye.

[0018]

As described above, according to the present invention, the effective aperture of the view lens provided in the viewfinder optical system of a single-lens reflex camera is formed to have a size such that the subject image on the focus glass can be viewed by both eyes of the photographer at the same time. However, since the photographer is configured to be able to observe the subject image formed on the focus glass through the view lens with both eyes, the balance between the accommodation and convergence of the left and right eyes and the visual field of the left and right eyes. Therefore, it is possible to stereoscopically view the subject image, and it is possible to perform photographing with less fatigue when observing the subject image and with easy focusing.

[Brief description of drawings]

FIG. 1 is a schematic rear perspective view of a single-lens reflex camera including a finder optical system of the present invention.

FIG. 2 is a schematic sectional view of the camera of FIG. 1 cut along the optical axis of a taking lens.

3 is a schematic perspective view of a finder optical system of the camera of FIG.

FIG. 4 is an equivalent configuration diagram of the finder optical system in FIG.

5 is an enlarged view showing a light diffusion state in a main part of FIG.

FIG. 6 is a schematic cross-sectional view showing another configuration example of the finder optical system.

FIG. 7 is a schematic cross-sectional view of a single-lens reflex camera for explaining a conventional viewfinder optical system.

[Explanation of symbols]

1 camera body 2 Shooting lens 3 Finder optical system 31 focus glasses 32 Daha Miller 33 Pellicle mirror 34 view lens 34A View (effective opening)

Claims (5)

[Claims] 1. A viewfinder optical system of a single-lens reflex camera, comprising: a focus glass for forming a subject image; and a view lens for magnifying and observing the subject image formed on the focus glass. The viewfinder optical system of a single-lens reflex camera, wherein the effective aperture of the lens is formed to have a size that allows the subject image on the focus glass to be viewed at the same time by both eyes of the photographer. 2. The viewfinder optical system of a single-lens reflex camera according to claim 1, wherein the effective aperture of the view lens has a size substantially equal to an interpupillary size of both eyes of the photographer. 3. A roof mirror or roof prism for inverting the left and right of a subject image formed on the focus glass and a half for inverting the top and bottom of the subject image between the focus glass and the view lens. A finder optical system for a single-lens reflex camera according to claim 1 or 2, further comprising a mirror. 4. The viewfinder optical system of a single-lens reflex camera according to claim 3, wherein the half mirror is a pellicle mirror. 5. In the focus glass, the light intensity of incident light passing through the focus glass in a straight direction is higher at a constant rate than the light intensity of transmitting in a direction having a predetermined angle with respect to the straight direction. The viewfinder optical system of a single-lens reflex camera according to claim 1, wherein the viewfinder optical system has a set light diffusion characteristic.