JPH02178644A - Single-lens reflex camera - Google Patents

Abstract

PURPOSE:To effectively use space and to make the whole camera thinner and smaller by properly arranging a pentaroof prism, a reflecting member, which has a reflecting surface and a specifically shaped roof, etc. CONSTITUTION:When a camera is used for a photographing system, a first reflecting member 4 is composed of a rectangular prism having a roof; an object picture formed by a photographing lens 2 is reversed to right and left to form the picture onto an image pickup plane 5. When the camera is used for a finder system, a second reflecting member 12 reflects a luminous flux, which has passed through the photographing lens 2, toward an optical axis 8 in a direction at almost 90 degrees to an optical axis 1, and makes the flux incident on the pentaroof prism 13 being a third reflecting member; it is emitted on an optical axis 10 nearly parallel to the optical axis 1 after the repetition of the prescribed reflection, thereby forming the finder picture of an erect normal picture onto the surface of a focusing plate 9. Thus, space can be effectively used, and the whole camera can be made thinner and smaller.

Description

Detailed Description of the Invention (Field of Application on AX) The present invention relates to a single-lens reflex camera, and particularly to a camera such as a photographic camera or a video camera, in which the vertical thickness of the camera can be adjusted by using a number of reflective members. This relates to a single-lens reflex camera that is thinner and more compact.

(Prior Art) Conventionally, in the optical system of a single-lens reflex camera such as a photographic camera or a video camera, a photosensitive surface 32 is disposed at the rear of a photographic lens 31 on the optical axis to form a photographing system, as shown in FIG. are doing.

Also, the light flux that has passed through the photographic lens 31 is reflected above the camera body by a rotating mirror 33 placed behind the photographic lens to form a finder image on the surface of the focusing plate 34, and the finder image on the focusing plate 34dj is converted into a condenser. Lens 35. A finder system is configured such that the image is observed as an erect image through a pentagonal roof prism 36 with a close-limit lens 37.

In this way, in a conventional single-lens reflex camera, the viewfinder light beam is reflected upward from the camera body by the rotating mirror 33.
A pentaprism placed above the photographic lens 31 is used to obtain an erect finder image. For this reason, the penta roof prism, which is part of the components of the finder system, protrudes upward, and when the photographic lens is attached to the camera body,
There was a tendency for cameras as a whole to become relatively large.

(Problem to be solved by the invention) In general, in a single-lens reflex camera shown in FIG.
The vertical direction) is approximately the sum of the height of the film and the penta-roof prism, the width direction is the sum of the photographing screen, the cartridge, and the film winding section, and the depth direction is approximately the total optical length of the photographing lens (from the 1921st surface of the II shadow lens). The overall shape is determined by the distance to the imaging plane), and the overall shape is stubby as shown in FIG. 3, which poses various problems in terms of portability and storage.

In particular, the pentagonal roof prism in a portion of the viewfinder system protruded, making it extremely difficult to make the camera thinner in the height direction with conventional single-lens reflex cameras.

The present invention is a camera in which space is used efficiently by appropriately arranging reflective members having reflective surfaces, roof surfaces of a specific shape, penta roof prisms, etc., and the overall thickness of the photographing system and finder system is reduced in the vertical direction. The purpose of the present invention is to provide a single-lens reflex camera suitable for photographic cameras, video cameras, etc., which can be easily made thin and compact as a whole.

(Means for Solving the Problems) The present invention reflects a light beam on the optical axis of the Makoto photographic lens in a direction of approximately 90 degrees with respect to the optical axis by a first reflecting member disposed behind the photographic lens. , a photographing system that guides light onto an imaging surface arranged approximately parallel to the optical axis, and a second reflective member that is fixedly or removably provided between the photographic lens and the first reflective member. a finder system that reflects a light beam on the optical axis of the lens in a direction of approximately 90 degrees with respect to the optical axis, first reflects it in a direction approximately parallel to the optical axis by a third reflecting member, and then guides the light to an eyepiece; It is characterized by having the following.

Particularly, the present invention is characterized in that the first reflecting member is constituted by a right-angled prism having a roof surface forming an angle of 45 degrees with respect to the optical axis of the photographing lens.

(Embodiment) FIG. 1 is a schematic diagram of the main part showing the optical path of the optical system of a single-lens reflex camera according to the first embodiment of the present invention.

The figure shows the case where it is used as an imaging system.

In the figure, 2 is a photographing lens, and 4 is a first reflecting member, which is a right-angled prism having a roof surface that forms approximately 45 degrees with respect to the optical axis l of the photographic lens 2. The light beam on the optical axis l of the photographic lens 2 is reflected in a direction of 90 degrees with respect to the optical axis l. Each time the shutter 14 is opened or closed, light is guided onto the imaging surface 5 of a film or the like arranged parallel to the optical axis l. The photographing system is constructed in this way.

In particular, in this embodiment, the first reflecting member 4 is constituted by a right-angle prism having a roof surface, and the subject image formed by the photographing lens 2 is horizontally inverted and formed on the imaging surface S.

As a result, a subject image without backburning is obtained, similar to the subject image formed on the imaging surface in the conventional single-lens reflex camera shown in FIG.

Next, the case where it is used as a finder system will be explained.

In this case, the second reflecting member 12 consisting of the photographing lens 2, the first reflecting member 4, and a rotatable mirror disposed in between is positioned at a dotted line in the direction of the arrow at an angle of 45 degrees with respect to the optical axis l. Then rotate it. At the same time, the shutter 14 disposed in front of the first reflecting member 4 is closed.

The light flux that has passed through the photographic lens 2 is reflected by the second reflecting member 12 in the direction of the optical axis 8, which is approximately 90 degrees with respect to the optical axis l.J11
3ff Make the light beam incident on the penta-roof prism 13 as a reflection member 0 Then, after repeating a predetermined reflection of the light flux that has entered the penta-roha prism 13, the optical axis lO is made approximately parallel to the optical axis l.
Let it eject upwards.

An erect finder image is formed on the focusing plate 9.

Then, the finder image of the erect normal image formed on the surface of the focusing plate 9 is viewed through the eyepiece 11. In this way, a finder system is constructed.

Note that 6 is a cartridge chamber for the film 5, and 7 is a winding chamber for the film 5.

The film holding shaft of the cartridge chamber 6 and the film winding shaft of the winding chamber 7 are set to be substantially parallel to the optical axis l.

In this embodiment, the central axes corresponding to the optical axes of each element constituting the photographing system and each element constituting the finder system are arranged on a substantially concave plane.

Further, the cartridge chamber and the film winding chamber are also arranged on a substantially concave plane, and the imaging surface, which is the film surface, is arranged in a plane parallel to the optical axis of the photographic lens 2.

As a result, the entire single-lens reflex camera has a flat shape that is low in the vertical direction and is easy to carry and store.

FIG. 2 is a schematic diagram of the main parts showing the optical path of the optical system according to the second embodiment of the present invention.

The figure shows a case where a finder image is observed using a finder system.

In this embodiment, an auxiliary lens 15 is disposed in front of the pentagonal roof prism 13, and the finder image formed on the surface of the focusing plate 9 by the photographing lens 2 is reduced and formed.

The magnification is preferably 0.2x to 0-8x.

If it is larger than 0.8x, there is little effect of making the finder system smaller, and if it is smaller than o.2x, the magnification of the eyepiece becomes too large and the configuration becomes complicated.

Then, the am magnification is increased by the eyepiece lens It by a value corresponding to the value reduced by the auxiliary lens 15, so that a finder image of a constant size as a whole is observed.

In this way, by using an auxiliary lens with light condensing properties, the pentagonal roof prism and focus plate can be downsized, and the distance between the first reflecting member and the film winding chamber can be reduced, effectively downsizing the entire camera. I'm trying.

The imaging system in the Hyakumoto embodiment is the same as that in the first embodiment shown in FIG.

1st. In the second embodiment, a part of the configuration may be configured as follows.

(b) By providing an auxiliary lens between the first reflecting member and the second reflecting member or between the second reflecting member and the film, aberrations of the photographing lens, especially off-axis aberrations, can be well corrected;
Furthermore, the total length of the lens can be shortened.

(b) If a spherical or aspherical system is provided on the incident side or the outgoing side of the second reflecting member, the same effect as in (a) above can be obtained.

(c) The second reflecting member may be composed of a right-angled prism or a simple mirror making an angle of 45 degrees with the optical axis.

In this case, a back-printed object is formed on the film surface, but there is no problem if this is corrected when printing or displaying on photographic paper or a display section.

(d) The distance between the second reflective member and the film winding chamber may be narrowed, and the eyepiece may be arranged so that its optical axis is located outside the film winding chamber.

(e) The second reflecting member may be a half mirror and may be fixedly disposed behind the photographing lens. This reduces the number of movable parts and makes the entire device anodic.

(Effects of the Invention) According to the present invention, as described above, by appropriately arranging each reflective member, pentagonal roof prism, etc., and aiming for effective use of space, the entire camera can be made thin and compact, especially in the height direction. A single-lens reflex camera suitable for a photographic camera, a video camera, etc. can be achieved.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing the main parts of the optical system of the first and second embodiments of the present invention, respectively, and FIG. 3 is a diagram of the conventional l IIJ
FIG. 2 is a schematic diagram of an optical system of a reflex camera. In the figure, l is the optical axis, 2 is the photographic lens, 4 is the first reflecting member, and 5
1 is an imaging surface (film surface), 6 is a battlerone chamber, 7 is a film winding chamber, 9 is a focusing plate, 11 is an eyepiece, 1
2 is a second reflecting member, 13 is a third reflecting member, 14 is a shutter, and 15 is an auxiliary lens.

Claims (2)

[Claims] (1) The first reflecting member placed behind the photographic lens directs the light beam on the optical axis of the photographic lens by approximately 90 degrees with respect to the optical axis.
A photographic system that reflects light in the 0 degree direction and guides the light onto an imaging surface arranged approximately parallel to the optical axis, and a first reflector that is fixedly or removably provided between the photographic lens and the first reflecting member. A second reflecting member reflects the light beam on the optical axis of the photographic lens in a direction of approximately 90 degrees with respect to the optical axis, and then a third reflecting member reflects the light flux on the optical axis in a direction approximately parallel to the optical axis. A single-lens reflex camera characterized by having a finder system that guides light. (2) The single-lens reflex camera according to claim 1, wherein the first reflecting member is constituted by a right-angle prism having a roof surface forming an angle of 45 degrees with respect to the optical axis of the photographic lens.