JPH0348833A - Ttl finder device - Google Patents

Abstract

PURPOSE:To make the entire height of a TTL finder device low and to suppress the entire height of a camera by setting the turning shaft of a 1st reflection mirror in the direction of the short side of a photographic picture and the direction of the major axis of a focusing plate in an optical axis direction and including a height which is expressed by the length of the short side xcos45 deg. in the entire height of the finder device. CONSTITUTION:Photographing luminous flux made incident through a photographing lens 1 is reflected by a quick return mirror 21 at a 1st position in the direction of the long side of the photographic picture, that means, in the right-to-left direction of the camera H1 to form the image of an object on the focusing plate 22. The image of the object is reflected by a 2nd reflection mirror 23 in the upward direction of the camera V, made incident on a 3rd reflection mirror 24 and reflected in the right-to- left direction of the camera H2. Furthermore, the reflected luminous flux is reflected by a 4th reflection mirror 25 toward the back of the camera and made incident on an ocular 7. Therefore, an operator can observe the erect image of the object in the finder just by looking in the ocular 7. The direction of the long side of the focusing plate 22 turns to the optical axis direction of the camera and the length of the short side xcos45 deg. is included in the height direction of the finder.

Description

[Detailed description of the invention] A. Industrial application field The present invention relates to a TTI and finder device.

B. PRIOR TECHNOLOGIES AND THEIR PROBLEMS As conventional finder devices, a porromirror type as shown in FIG. 3 and a pentaprism type as shown in FIG. 4 are known.

The Porro mirror type TTL finder device shown in FIG. 3 includes a quick return mirror 2 that reflects the photographing light flux incident from the photographic lens 1 upward to the camera, and a focus plate that forms a subject image using the reflected light flux of the quick return mirror 2. 3, and reflecting mirrors 4 to 6 that sequentially reflect the subject image formed on the focus plate 3 and guide it to the eyepiece 7. Note that 10 is a film cartridge, and 11 is a take-up spool.

The pentaprism type TTL finder device shown in Fig. 4 is
It is composed of a quick return mirror 2 and a focus plate 3, which are the same as the Porro mirror type, and a pentaprism 8 that reflects the subject image formed on the focus plate 3 three times on the inner surface of the prism and guides it to the eyepiece 7.

Although the Porro mirror type is easy to manufacture, it is difficult to downsize, has a low viewfinder magnification, requires a field lens, and is expensive. On the other hand, although pentaprism type TTT and finder devices are difficult to manufacture, they are compact and easy to assemble, so they are now mainstream in single-lens reflex cameras. However, the prism apex is high with respect to the finder optical axis, increasing the overall height of the camera.

An object of the present invention is to provide a compact TTL finder device that can keep the overall height of the camera low.

Means for solving the problem of section C1 This will be explained with reference to FIG. 1, which is an embodiment of the present invention.
The present invention is applied to a TTL finder device of a camera that forms an object image on a camera. Then, it rotates between a first position and a second position around a rotation axis extending in the short side direction of the photographing screen, and in the first position, the photographic image is incident through the photographing lens 1. A first reflecting mirror 21 that reflects the light beam in the long side direction of both photographing surfaces and retreats from the photographing optical path at the second position so that the photographing light beam is guided to the recording medium F1; a focusing plate 22 on which a subject image is formed by the light beam reflected from the reflecting mirror 21;
A second reflecting mirror 23 that reflects the image of the camera in the short side direction of the photographing screen, and a second reflecting mirror 23 that directs the light beam of this second reflecting mirror 23 in the long side direction opposite to the direction in which the light beam enters the second reflecting mirror 23. A third reflecting mirror 24 that reflects, and this third reflecting mirror 2
The fourth reflecting mirror 25 reflects the light beam from the fourth reflecting mirror 25 toward the rear of the camera, and the eyepiece lens 7 receives the reflected light beam from the fourth reflecting mirror 25 to form a finder image.

The first reflecting mirror has a rectangular shape corresponding to both sides of the photographing surface, and is tilted so that its long side forms a 45 degree angle with the photographing light beam, so that the photographing light beam is transmitted toward the recording medium and reflected in the direction of the long side. You can do it like this.

09 Effect In the TTL finder device configured in this way,
The height of the TTL finder device can be reduced for the following reasons.

If the short side of the reticle is oriented toward the camera optical axis as in the conventional case, the height of the long side of the focus plate (X cos 45°) is T.
T r, included in the total length of the finder device. However, if the rotation axis of the first reflecting mirror 21 is set in the direction of the short side of the photographing screen as in the present invention, and the long side direction of the focus plate 22 is set in the direction of the optical axis, then the short side length of the frame is Xcog45.
The height expressed in degrees is included in the total height of the TTL finder device. Therefore, compared to the conventional device, the T T L
The overall height of the finder device can be reduced.

E. Embodiment FIG. 1 is a perspective view of a TTL finder device showing an embodiment of the present invention. The same parts as in FIG. 3 will be described with the same reference numerals.

The V direction in Figure 1 is the vertical direction of the camera, Hl.

The H2 direction is the left-right direction, and the film (recording medium) in the film cartridge 1o is fed in the H1 direction and wound onto the film spool 11. Reference numeral 21 denotes a quick return mirror as a first reflecting mirror, which is rotatable in the direction of arrow R around a rotation axis extending in the vertical direction of the camera. The length of the short side of this quick return mirror 21 is approximately the length of the short side of the photographing screen, and the length of the long side is X cos 45 degrees, which is the length of the long side of both photographing surfaces. The photographing light flux incident from the lens 1 is reflected in the camera lateral direction H1, and at the second position rotated 45 degrees counterclockwise from this first position, the photographing lens 1
The photographing light beam passing through the camera passes through a rectangular photographing screen (not shown) and forms an image on the film FI, thereby exposing the film FI.

Reference numeral 22 denotes a rectangular focus plate corresponding to both photographing surfaces, and a subject image is formed by the light beam reflected from the quick return mirror 21 located at the first position.

Reference numeral 23 denotes a second reflecting mirror, which is tilted at an upward slope of 45 degrees in the short side direction with respect to the focus plate 22, and reflects the subject image on the focus plate 22 in the upward direction V of the camera. The length of the long side of this second reflecting mirror 23 is approximately the length of the long side of the photographing screen, and the length of the short side is approximately the length of the short side of both photographing surfaces X cos 45°
It is said that Further, 24 is a third reflection mirror, and 24 is a third reflection mirror.
The reflected light beam from the reflecting mirror 23 is transferred to the second reflecting mirror 2.
3 is reflected in the camera lateral direction H2, which is opposite to the direction H1 of the incident light beam. The length of its long side is shorter than the length of the long side of both photographing surfaces and the length of the second reflecting mirror 23, and the length of its short side is also the length of the short side of the photographing screen and the short side of the second reflecting mirror 23. be made shorter than its length.

25 is a fourth reflecting mirror, and the third reflecting mirror 24
The quick return mirror 21 is tilted at an angle perpendicular to the quick return mirror 21 so as to reflect the incident light flux from the camera to the eyepiece lens 7 at the rear of the camera. The length of its long side is approximately the length of the long side of the third reflecting mirror 24, and the length of its short side is approximately that of the third reflecting mirror 24.
is made shorter than the long side length X cos 45°.

In the TTL finder device configured in this way, the photographing light beam incident through the photographing lens 1 is reflected by the quick return mirror 21 located at the first position in the long side direction of the photographing screen, that is, in the left-right direction 111 of the camera, and is focused Board 2
A subject image is formed on 2. This subject image is reflected in the upward direction V of the camera by the second reflection mirror 23, enters the third reflection mirror 24, and is further reflected in the left-right direction H2 of the camera. The reflected light beam is further reflected toward the rear of the camera by the fourth reflecting mirror 25 and enters the eyepiece lens 7. Therefore, by looking through the eyepiece lens 7, the operator can observe an erect image of the subject within the finder.

In such a TTL finder device, the focus plate 2
Since the long side direction of 2 faces the camera optical axis direction, the focus plate 22
(The length of the short side Xcos45°) is included in the height component of the TTL finder device, and (The length of the long side Xcos45°) is included in the height component of the TTL finder device.
@) is included in the height of the TTL finder device, which allows the overall height to be lower than that of a conventional TTL finder device.

In addition, although the case where the quick return mirror 21 is used as the first reflecting mirror has been described above, it is also possible to use a half mirror fixed at the first position as the first reflecting mirror. Left and right direction H
1 and H2 have been described, but the present invention can also be applied to a format in which the paper is fed in the vertical direction V. Additionally, it can be used with either full-frame or half-frame cameras. Furthermore, it can be used in magnetic recording still cameras, video cameras, 8-channel cameras, etc.

Effects of the F0 Invention Since the present invention is configured as described above, the TT
The total height of the L finder device can be reduced, and thus the total height of the camera can also be suppressed.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the overall configuration of the TTr and finder device according to the present invention, FIG. The front view of the TTL finder device, Figures 3 and 4, show the conventional Boro mirror type and pentaprism type TT.
FIG. 2 is an overall perspective view of the L finder device. 1: W1 shadow lens 7: Eyepiece 721: Quick return mirror 22: Focus plate 23: Second reflective mirror 24: Third reflective mirror 25: Fourth reflective mirror

Claims (1)

[Scope of Claims] 1) In a TTL finder device for a camera that forms a subject image on a recording medium by a photographing light flux passing through a rectangular photographing screen, the camera has a rotation axis centered on a rotation axis extending in the short side direction of the photographing screen. The camera rotates between a first position and a second position, and in the first position, the photographing light beam incident through the photographing lens is reflected in the long side direction of the photographing surfaces, and in the second position, a first reflecting mirror that retreats from the photographing optical path so that the photographing light beam is guided to the recording medium; and a subject image is formed by the light beam reflected from the first reflection mirror located at the first position. a focusing plate; a second reflecting mirror that reflects the image of the focusing plate in the direction of the short side; and a long side opposite to the direction in which the luminous flux of the second reflecting mirror is incident on the second reflecting mirror. A third reflecting mirror that reflects the light in the direction of the camera, a fourth reflecting mirror that reflects the light from the third reflecting mirror toward the rear of the camera, and the reflected light from the fourth reflecting mirror entering the camera to form a finder image. A TTL finder device comprising an eyepiece lens. 2) In a TTL finder device of a camera that forms a subject image on a recording medium by a photographing light beam passing through a rectangular photographing screen, the TTL finder device has a rectangular shape corresponding to the photographing screen, and its long side is at an angle of 45 degrees with the photographing light beam. a first reflecting mirror that is tilted so as to transmit the photographing light flux toward the recording medium and reflects it in the long side direction; and a subject image is formed by the light flux reflected from the first reflection mirror. a second reflecting mirror that reflects the image of the focusing plate in the direction of the short side; and a second reflecting mirror that directs the light beam of the second reflecting mirror to a length opposite to the direction in which the light beam enters the second reflecting mirror. A third reflecting mirror that reflects in the side direction; a fourth reflecting mirror that reflects the light from the third reflecting mirror toward the rear of the camera; and the reflected light from the fourth reflecting mirror enters and forms a finder image. A TTL finder device comprising an eyepiece lens.