JPH1124134A - Finder device for single lens reflex camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize space saving of a finder part and to improve photometric efficiency so as to obtain an excellent photometric result in the case of installing a photometric device in a hollow pentagonal mirror. SOLUTION: This device is equipped with the hollow pentagonal mirror 1 consisting of a roof part 2 having 1st and 2nd reflection mirrors 2a and 2b and a 3rd reflection mirror 3 for guiding light reflected by the roof part 2 to oculars 5 and 6. It is equipped with a photometric lens 8 disposed above an emitting surface 1b being a surface formed on the mirror 1 and orthogonally crossed with the optical axes of the oculars 5 and 6 and condensing the light on a photometric element 9. Then, a light shielding member 10 is provided between the oculars 5 and 6 and the lens 8 so that its tip is protruded to the inside of the mirror 1 from the emitting surface of the mirror 1, and the tip 10a of the member 10 is positioned at a part where the light 11 formed with the lower edge of a finder field as a boundary in the mirror 1 is not intercepted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder device for a single-lens reflex camera having a penta-mirror, particularly a hollow penta-mirror comprising a plurality of reflection mirrors, in a single-lens reflex camera.

[0002]

2. Description of the Related Art There is known a viewfinder optical system of a single-lens reflex camera using a pentaprism to which a function of a photometric device for a subject is added. That is, a photometric lens for condensing light on a photometric element is provided close to the upper part of the exit surface on the rear end side of the pentaprism. In the photometric device attached to such a conventional finder device, light incident on the pentaprism from a focusing plate disposed close to the entrance surface below the pentaprism is first and second light beams at the roof portion of the pentaprism. The light is reflected by the left and right sides being inverted forward and backward by the second reflecting surface, and again reflected backward by the third reflecting surface to be guided to the photometric lens.

A recent single-lens reflex camera employs a viewfinder optical system using a hollow penta-mirror formed by combining a plurality of reflection mirrors in place of a conventional glass penta-mirror in order to reduce the weight. (See, for example, Japanese Utility Model Laid-Open No. 5-52831). In such a viewfinder optical system using a hollow pentamirror, an aperture for subject photometry is provided above the exit surface formed on the rear end side of the roof, and the light is focused on a photometric element behind the aperture. Photometric lens to be placed. In order to save space in the viewfinder, such a photometric lens
It is desirable to arrange as close as possible behind the opening above the exit surface.

[0004]

However, in the above-described finder optical system using the hollow pentamirror, the light traveling from the reticle to the upper part of the exit surface at the rear end of the roof differs from the conventional glass pentaprism. The light is not totally reflected by the exit surface, but directly enters the periphery of the photometric lens through the photometric opening. Therefore, the light receiving element also receives light other than the light beam for photometry guided through the reflecting surface, which affects the photometric result, and there is a problem that it is not expected to obtain a good photometric result.

[0005] In addition, since light other than for photometry enters around the photometric lens, it cannot be seen from a normal eye position.
There is also a problem that when looking into the eyepiece from above, the periphery of the photometric lens is visually recognized as a ghost, and the quality of the finder is questioned.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is desirable to reduce the amount of light directly incident from the reticle to the periphery of the photometric lens while saving the space of the finder section by the hollow pentaprism. It is an object of the present invention to obtain a finder device of a single-lens reflex camera which can provide a finder optical system in which a photometry result can be expected and a ghost is not noticeable around the photometry lens.

[0007]

In order to meet such an object, a finder device for a single-lens reflex camera according to the present invention comprises a roof section having first and second reflection mirrors, and a light reflected by the roof section. Pentamirror composed of a third reflecting mirror for guiding the light to the eyepiece, and a surface formed on the hollow pentamirror and disposed above an exit surface orthogonal to the optical axis of the eyepiece. A light-measuring lens for converging light on the light-measuring element, and a light-shielding member between the eyepiece and the light-measuring lens such that the tip protrudes inward from the exit surface of the hollow pentamirror. And the front end of the light-shielding member is positioned at a portion in the hollow pentamirror that does not block light formed at the lower end edge of the finder field.

In the finder device for a single-lens reflex camera according to the present invention, the front end of the light-blocking member facing the inside of the hollow penta-mirror is shaped so as not to block light formed at the upper end edge of the finder field. It is formed. Further, the finder device of the single-lens reflex camera according to the present invention is characterized in that the tip of the light-blocking member facing the inside of the hollow pentamirror includes It is configured such that light reaching the photometric lens can be blocked without passing through any of the mirrors. In the finder device for a single-lens reflex camera according to the present invention, the light-blocking member is formed integrally with a reflection mirror constituting a hollow pentamirror.

According to the present invention, since the light other than for photometry is guided to the photometric lens by the light shielding member provided with the tip protruding inward of the pentamirror, a photometric error can be reduced, and a favorable photometric error can be reduced. It can be expected that photometric results will be obtained.

Further, according to the present invention, since the amount of light from the focusing screen directly to the periphery of the photometric lens through the photometric opening provided at the rear end side of the roof portion of the hollow pentamirror can be reduced. By arranging the lens near the exit surface of the pentamirror, it is possible to reduce the size, obtain a good photometric result, and obtain a finder optical system in which a ghost is inconspicuous.

[0011]

1 and 2 show one embodiment of a finder device for a single-lens reflex camera according to the present invention. In these figures, reference numeral 1 denotes a hollow pentaprism formed by a plurality of reflection mirrors, and a roof part 2 having first and second reflection mirrors 2a and 2b intersecting at substantially right angles, and a roof part 2 of the roof part 2. A third reflecting mirror 3 having a third reflecting surface 3a for guiding light reflected forward by the respective reflecting mirrors 2a and 2b to eyepieces 5 and 6 provided in the eyepiece 4. ing.

Reference numeral 7 denotes a reticle disposed close to the entrance surface 1a below the hollow pentamirror 1. Light reflected by the reflection mirror is guided to the reticle 7 through a photographic lens (not shown). From this focusing screen 7, the hollow pentamirror 1
The light incident on the inside is reflected by the reflecting surfaces of the reflecting mirrors 2a and 2b of the roof part 2 and the reflecting surface 3a of the third reflecting mirror 3, and is reflected by the focusing screen 7 formed on the rear end side of the roof part 2. The light passes through the opening 1c provided in the vertical exit surface 1b, passes through the first eyepiece 5 and the second eyepiece 6, and reaches the eyes of the photographer.

The opening 1c of the exit surface 1b has a function of narrowing the light beams directed to the lower part of the field of view and the left and right directions among the light beams guided to the eyepieces 5 and 6, and the exit surface 1 to which the light beam for photometry is guided.
b Continued up to the top. Reference numeral 8 denotes a photometric lens which is disposed close to the upper part of the above-mentioned exit surface 1b and converges on a photometric element 9. A light beam for photometry condensed by the photometric lens 8 forms an object image on the photometric element 9. Photometry can be performed by forming an image.

According to the present invention, the light shielding plate 10 is provided between the eyepieces (5, 6) and the photometric lens (8) at the opening 1c of the exit surface 1b of the hollow pentamirror 1 described above. Provided. The light-shielding plate 10 does not block the light rays 11 constituting the boundary at the lower edge of the finder field of the finder light from the exit surface opening 1c toward the front of the interior of the hollow penta-mirror 1. It protrudes. Further, the front end portion 10a of the light-shielding plate 10 is bent downward in an L-shape, and is formed in a shape that does not block light that is formed with the upper edge of the finder field as a boundary. Forming a part.

Here, of the light incident from the reticle 7 disposed close to the incident surface 1a below the pentamirror 1, the light incident on the photometric lens 8 does not pass through any reflecting surface of the pentamirror 1. The amount of light going to the tip 10a of the light-shielding plate 10
It is configured to reduce by. The light shielding plate 10
Of the third reflecting surface 3 in the pentamirror 1
Of the light reflected from a and guided to the eyepieces 5 and 6, it is necessary to position the light so as not to block the light that forms the boundary at the upper edge of the finder field.

Since the light-shielding plate 10 protrudes from the exit surface 1b into the interior of the hollow penta-mirror 1, the amount of light directly traveling from the focusing plate 10 to the photometric lens 8 can be reduced. Therefore, extra light other than the light beam for photometry is reduced from being guided to the photometric element 9, and a good photometric result and a finder optical system in which a ghost is not noticeable can be obtained.

FIGS. 3 and 4 show a second embodiment of the finder device for a single-lens reflex camera according to the present invention. Also in this embodiment, the finder optical system has the same arrangement of the optical components as in the above-described first embodiment, and the photometric lens 8 is disposed in a portion close to the upper rear of the exit surface 1b. Have been.

In the cavity type pentamirror 1 shown in this embodiment, a portion forming a lower finder field and a portion facing the photometric lens 8 are formed on an exit surface 1b formed on the rear end side of the roof portion 2. The light shielding portion 20 is integrally formed with the roof portion 2 constituting the hollow pentamirror 1 so as to partition. The light-shielding portion 20 forms an aperture 21a that serves as a stop in the vertical and horizontal directions of the finder field light beam toward the eyepiece lenses 5, 6, and an opening portion 21b that guides the light beam toward the photometric lens 8.

Here, the above-mentioned light-shielding portion 20 is formed such that the upper edge portion of the lower opening portion 21a does not block light constituting the boundary with the upper edge of the finder field of view.
In addition, it forms a stop for the light beam 22 reaching above the finder field.

Further, the inner end portion of the light-shielding portion 20 facing the inside of the pentamirror 1 blocks light rays 11 formed on the lower end edge of the finder field toward the inside from the exit surface 1b. It is formed in a convex shape without any. Due to the inner end of the convex shape, it is possible to reduce the light amount of the light beam going directly from the focusing screen 7 to the periphery of the photometric lens 8, and a good photometric result and a finder optical system with less ghost phenomenon can be expected.

The present invention is not limited to the structure described in the above embodiment, and it goes without saying that the shape, structure, etc. of each part can be appropriately modified or changed. For example, the shape and structure of the hollow prism, and the structure and arrangement of the eyepieces in the viewfinder eyepiece are appropriately modified.
It is free to change.

[0022]

As described above, according to the finder device of the single-lens reflex camera according to the present invention, the light shielding member is separately or integrally formed so as to protrude inward from the exit surface of the hollow pentamirror. And the tip of this light shielding member is positioned in the hollow pentamirror at a position that does not block light that is formed with the lower end edge of the viewfinder field as a boundary. It has the excellent effects described in (1).

That is, according to the present invention, the amount of light that goes directly from the reticle to the periphery of the photometric lens through the photometric opening provided on the rear end side of the roof portion of the hollow pentamirror is determined by the eyepiece and the photometric lens. Can be reduced by the presence of the light-blocking member provided between the hollow pentamirror and the light-measuring lens.

Therefore, the arrangement space of the finder portion including the photometric device including the photometric lens disposed facing the upper part of the exit surface on the rear end side of the hollow pentamirror and the photometric element disposed behind the lens is substantially reduced. The size of the entire camera can be reduced. In addition, since the photometric lens approaches the exit surface of the pentamirror, the amount of light condensed on the photometric lens increases, photometric efficiency improves, and good photometric results can be obtained. Further, it can be expected to obtain a finder optical system which does not cause ghost which is a problem due to light around the photometric lens.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a finder device for a single-lens reflex camera according to the present invention, and is a cross-sectional view of a finder optical system using a hollow pentamirror.

FIG. 2 is a perspective view showing a first embodiment of a finder device for a single-lens reflex camera according to the present invention, and showing features of FIG. 1;

FIG. 3 is a sectional view of a finder optical system using a hollow pentamirror according to a second embodiment of the finder device for a single-lens reflex camera according to the present invention.

FIG. 4 is a perspective view of a finder device for a single-lens reflex camera according to a second embodiment of the present invention, which is a feature of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... hollow pentamirror, 1a ... entrance surface, 1b ... exit surface, 1c ... opening part, 2 ... roof part, 2a, 2b ... 1st, 2nd reflection mirror, 3 ... 3rd reflection mirror, 3a ... Third reflecting surface, 4 ... eyepiece, 5, 6 ... eyepiece, 7 ... focusing plate, 8 ... photometric lens, 9 ... photometric element, 10 ... light shielding plate (light shielding member), 10a ... tip, 11 ... Light rays, 20: light shielding part (light shielding member), 21a, 21b: opening, 22: light ray.

Claims (4)

[Claims] 1. A hollow pentamirror comprising: a roof portion having first and second reflecting mirrors; and a third reflecting mirror for guiding light reflected by the roof portion to an eyepiece. A finder device for a single-lens reflex camera, comprising: a surface formed on a pentamirror, which is provided above an exit surface orthogonal to an optical axis of the eyepiece, and provided with a photometric lens for condensing light on a photometric element. A light-blocking member is provided between the lens and the photometric lens such that a tip of the light-blocking member projects from the emission surface of the hollow pentamirror to the inside of the pentamirror. A finder device for a single-lens reflex camera, characterized in that the finder device is located at a position where the light formed at the lower end edge of the finder visual field as a boundary is not blocked. 2. A finder device for a single-lens reflex camera according to claim 1, wherein a front end of the light-blocking member facing the inside of the hollow penta-mirror does not block light formed at an upper edge of the finder field. A finder device for a single-lens reflex camera, wherein the finder device is formed. 3. The finder device for a single-lens reflex camera according to claim 1, wherein the light-shielding member has a tip facing the inside of the hollow penta-mirror close to an incident surface below the hollow penta-mirror. A finder device for a single-lens reflex camera, characterized in that it is configured to be able to block light that reaches the photometric lens without passing through any of the reflecting mirrors of the pentamirror, of the light incident from the disposed focusing screen. 4. A single-lens reflex camera finder device according to claim 1, wherein the light shielding member is formed integrally with a reflection mirror constituting a hollow pentamirror. Viewfinder for reflex camera.