JPH026935A - Compact single-lens reflex camera - Google Patents

Abstract

PURPOSE:To make an entire camera thin and small-sized by appropriately arranging plural reflecting mirrors as bending means and a lens used for condensing or forming an image. CONSTITUTION:An image pickup plane is placed parallel to the optical axis O of a photographing lens 1; at the time of exposing the image pickup plane, a luminous flux L1 which has passed through the photographing lens 1 is reflected, by the first reflecting mirror M1, in directions orthogonal to the optical axis O of the photographing lens and parallel to the image pickup plane; and the reflected luminous flux L2 is led to the image pickup plane by the second reflecting mirror M2. On the other hand, at the time of observing a finder, the second reflecting mirror M2 is retreated and the third reflecting mirror M3 is then inserted in the space, created by the retreat of the mirror M2, in order to constitute a finder system; so the luminous flux L2 reflected from the first reflecting mirror M1 is led in a direction different from the image pickup plane. Thus, the entire camera can be made thin and smalll-sized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a compact single-lens reflex camera, and particularly to its optical system.

[Conventional technology]

Conventionally, in the optical system of a single-lens reflex camera such as a photographic camera or a video camera, a photosensitive surface 53 is disposed behind a photographic lens 51 on the optical axis to constitute a photographing system, as shown in FIG.

Further, the light flux that has passed through the photographic lens 51 is reflected upward of the camera body by a rotating mirror 52 placed behind the photographic lens to form a finder image on the surface of the focusing plate 54. The finder system is configured such that the finder image on the surface of the focusing plate 54 is observed through the condenser lens 55 and the pentaprism 56 as an erect normal image with the eyepiece lens 57.

In this way, in the conventional eye reflex camera, the rotating mirror 52
The finder light beam is reflected above the camera body, and a pentaprism placed above the photographing lens 51 is used to obtain an erect finder image. For this reason, the pentaprism, which is part of the components of the finder system, protrudes above the camera body, and when a photographic lens is attached to the camera body, the overall camera tends to become relatively large. In particular, in the conventional configuration using a pentaprism, a portion of the camera has a protruding shape, making it extremely difficult to reduce the thickness of the entire camera in the vertical direction.

Furthermore, when a zoom lens, telephoto lens, or the like is used, the photographing system tends to protrude and the overall size of the camera tends to increase.

By the way, as compact single-lens reflex cameras related to the present invention, Japanese Patent Laid-Open No. 54-99623 and Japanese Utility Model Publication No. 54-8736 are known.

[Problem that the invention seeks to solve]

The present invention does not use the conventional pentaprism, but by appropriately arranging a plurality of reflecting mirrors as optical path bending means and lenses for condensing or imaging, the thickness of the photographing system and finder system can be reduced as a whole. The purpose of the present invention is to provide an optical system having an optical path bending means that can be efficiently housed in a thin space and easily reduce the thickness and size of the entire camera.

Another object of the present invention is to provide a compact optical system, especially for an eye reflex camera, in which the photographing system does not protrude too much even when a zoom lens, telephoto lens, etc. are used.

[Means for solving problems]

Further, in the present invention, an imaging surface is arranged parallel to the optical axis of the photographing lens, and when the imaging surface is exposed, the light beam passing through the photographing lens is reflected by a first reflecting mirror in a direction perpendicular to the optical axis of the photographing lens. The reflected light beam is reflected in a direction parallel to the imaging surface, and the reflected light beam is guided to the imaging surface by a second reflecting mirror, while the second reflecting mirror is retracted during viewfinder observation. In order to configure a finder system by inserting a third reflecting mirror in the space created by this, this is achieved by guiding the light beam reflected by the first reflecting mirror in a direction different from the direction of the imaging plane.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings. FIG. 1 shows a perspective view of the optical system of a single-lens reflex camera according to the present invention. Note that this perspective view mainly depicts the finder system. 1 is a photographing lens including a variable magnification unit and a shutter, F is a film, and M is a first reflecting mirror, which is arranged at an angle of 45 degrees to the photographing optical axis O and in a direction perpendicular to the optical axis O. Therefore, the light beam L1 from the photographic lens is reflected in a direction parallel to the film surface. M is a second reflecting mirror for guiding light to the film surface, and maintains a state parallel to the film surface when observing a finder image. On the other hand, during exposure, the film is positioned at an angle of 45° to the film surface. M, is a light beam bundled by the third reflecting mirror,
is reflected toward the subject side in a direction parallel to the photographing optical axis 0 and the film surface. In addition, 1st. Second. The third reflecting mirror is set between the cartridge 3 and a film winding section (not shown). 4 is a focusing plate arranged near the image plane position. M4 is a fourth reflecting mirror, which is perpendicular to the photographing optical axis 0 and the film surface, and reflects the light beam in a direction away from the film surface. M is a fifth reflecting mirror that guides the light beam L4 toward the eyepiece lens 20. e is the eye point. 10 is a light shielding plate provided to prevent unnecessary exposure of the film.

The above finder configuration, that is, reflector M++M,,M
, , M form a boromirror system, and through the eyepiece the observer can observe the image formed on the focusing plate by the photographing lens 1 as an erect normal image.

Next, we will discuss the second case of configuring the photographic optical system during exposure.
I will explain this with reference to the diagram. FIG. 2 shows a perspective view of the photographing optical system during exposure. Note that the viewfinder optical system is omitted here.

Now, when an exposure start signal is output from the release switch (not shown) in the state of the finder optical system shown in FIG.
Achieves rotation in the direction shown by . Next, the second reflecting mirror M,
But axis I! 2 in the direction indicated by the arrow d, and stops at an angle of 45° to the film surface, as shown in FIG. Then, by operating a lens shutter (not shown), the film can be exposed. In this embodiment, the eyepiece shutter 1
9 is provided and is configured to operate to prevent exposure of the film surface by reversely incident light.

Next, a second embodiment is shown in FIG. This embodiment differs from the previous embodiment in that a prism body is embedded in the optical path from the focusing plate 4 to form the fourth and fifth reflecting mirrors. In this embodiment, the finder magnification is increased by shortening the air equivalent length within the finder.

Next, a third embodiment will be shown based on FIG. In this embodiment, the light beam on the optical axis L1 that has passed through the photographic lens 1 is reflected vertically and parallel to the film surface by the reflecting mirror M, and is withdrawn from the optical path during optical observation to shield the film surface. A movable reflector M that appears above the reflector M that is
is reflected vertically above the camera. Reflector M.

The light beam reflected by the lens is focused on a focusing plate 4 disposed at a position that is stationary with respect to the film surface 2. The optical path after the focusing plate 4 is bent in the opposite direction parallel to the optical axis L4 by the reflecting mirror M4 so as to become a beam of light having the optical axis L4, and then bent by the reflecting mirror M to be parallel to the optical axis of the photographing lens. Thus, the image on the focusing plate 4 can be visually observed. This configuration is still M, , M, , M4M6
Because a porromirror system is formed, the viewfinder observation state is an erect normal image. In addition, a movable reflecting mirror M,
For example, the object that was next to the photographic lens 1 may slide and come on top of the retracted reflecting mirror M2. Of course, at the time of photographing, the reflecting mirror M is in the same position as in FIG. In this case as well, the reflecting mirrors M, . . . M6', etc. may be constituted by prisms.

The film used in this example described above is 35 m long.
I am using an m film size, but I am using this as a half size.

Further, in this embodiment, a lens shutter is used, but a far cal-brane shutter may also be used.

〔Effect of the invention〕

As explained above, according to the present invention, a photographing system is configured in which the photographing optical path is bent twice, and the second and third
By efficiently moving the reflecting mirror, it is possible to provide an extremely compact and portable single-lens reflex camera.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the optical system of the present invention, FIG. 2 is a perspective view of the optical system of the present invention shown in FIG. FIG. 4 is a perspective view showing a third embodiment of the present invention, and FIG. 5 is a diagram showing a conventional example. 1...Photographing lens, M, , M, , M, , M, , M, . . . in order, first, second
, third, fourth, and fifth reflecting mirrors.

Claims (3)

[Claims] (1) A photographing system is constructed by arranging a first and a second reflecting mirror behind the photographing lens during exposure to the imaging surface, while retracting the second reflecting mirror during viewfinder observation; A compact single-lens reflex camera characterized in that a finder system is constructed by arranging a third reflecting mirror in a retracted space for guiding the light flux from the photographic lens to the eyepiece. (2) A single-lens reflex camera in which the photographing surface is arranged parallel to the optical axis of the photographing lens, and the light flux passing through the photographing lens is perpendicular to the optical axis of the photographing lens, and a first reflecting mirror that reflects the light in a direction parallel to the imaging surface; the light beam reflected by the first reflecting mirror is guided to the imaging surface during photographing, and is reflected from the first reflecting mirror during viewfinder observation; The second one that retreats outside the luminous flux
A compact single-lens reflex camera characterized by comprising a reflector, and a third reflector that is inserted into the light beam reflected by the first reflector during viewfinder observation and reflects the light beam to the eyepiece. . (3) the second reflecting mirror is pivoted at one end and maintained parallel to the imaging surface during viewfinder observation;
3. A compact single-lens reflex camera according to claim 1 or 2, wherein the camera is maintained at an angle of 45 degrees with respect to the imaging surface when the imaging surface is exposed to light.