JPS6012615B2 - Single-lens reflex camera with changeable screen size - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single-lens reflex camera in which the screen size can be changed by replacing the photographing lens, film back, and finder.

For single-lens reflex cameras, the screen size of the film used is predetermined depending on the camera model.

However, since films with various screen sizes are commercially available, and new types of films are being developed, it is desirable to be able to arbitrarily change the screen size depending on the purpose of photographing. In view of the above circumstances, it is an object of the present invention to provide a single-lens reflex camera whose screen size can be easily changed.

The single-lens reflex camera of the present invention is equipped with a large-format viewfinder, film back, and photographic lens instead of a normal-format viewfinder, film back, and photographic lens, so that the screen can be changed from normal to large format using the same camera body. The feature is that the size can be easily changed.

In this way, since the present invention uses the most expensive camera body in common without replacing it, it is possible to provide a camera system in which the screen size can be changed at low cost.
Furthermore, since the Honsha Tai uses the same camera body, the film surface of the large-format film back is positioned further back than that of the regular-format film back.

The back focus of a large-format photographic lens is lengthened by the displacement of the film surface, and the focusing V point plate of the large-format finder is positioned upwards by that amount and is the same size as the film screen. has been done. Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side sectional view showing an embodiment in which the screen size is for normal size.

A reflecting mirror 11 is reversibly disposed inside the camera body 101 to guide subject light to a finder optical path. One end of a light shielding plate 12 is attached coaxially with the reflecting mirror 11, and is designed to flip upward together with the reflecting mirror 11 to open the screen frame 13 during photographing. Behind this screen frame 13, a regular format film 14, for example, a 4.5×6-size film, is arranged in a plane.
This regular-format film 14 is arranged so as to be windable in a regular-format film bag 15, and is adapted to be removably attached to the rear of the camera body 10.
A lens mount section 16 is provided at the front of the camera body 0, and a normal format photographic lens 17 is detachably mounted on this lens mount section 16.

This photographic lens 17 has a built-in lens shutter 18. Note that the camera body 10 is provided with a focal plane shutter. In some cases, the lens shutter 18 may be omitted. Of course, in the case of this camera body with a focal plane shutter, the light shielding plate 12 is omitted. A focus plate 20 is removably disposed on the upper shoulder portion 19 of the camera body 10.

This focusing plate 20' is provided at a position optically conjugate with the film 14. A normal format finder 21 is removably attached to the camera body 101 above the focusing plate 20. Note that the focusing plate 20 may be attached within the normal format finder 21 by shifting the mounting portion of the normal format finder downward. This makes it convenient to replace the focus plate 20 when replacing the normal format finder. In this way, when the camera body 101 is equipped with the regular-format film bag 15, the photographing lens 17, and the finder 21, photography is performed using the normal screen size of the camera body.

FIG. 2 is a side sectional view showing an embodiment in which the screen size is changed from normal size to large size.

In the present invention, since the same camera body 10 is used, the screen frame 13 is constant. Therefore, the screen was made larger by shifting the film surface backwards. That is, the large-format film back 22 is loaded with a large-sized (8×8) film 23, such as a Polaroid film back (film back manufactured by Polaroid), and is loaded with a film 23 of a large size (8 x 8). Instead, it is attached to the rear of the camera body 0 via a light-shielding film back connector 24. In addition, this film back connection body 24 and the large-sized film back 22 may be integrated. Lens mount section 1 of camera body 10
6, a large format photographic lens 25 is attached in place of the regular format photographic lens 17.

This large-format photographic lens 25 includes a film back connecting body 2
Since the film surface is located at the rear by the length of 4, the back focus is longer than that of a regular format photographic lens.
Furthermore, since the film surface is away from the screen frame 13, a focal plane shutter cannot be used, so a lens shutter 26 is built into the large-format photographic lens 25. Note that the camera body 10 is provided with a focal plane shutter. In this case, the focal plane shutter may be left fully open and the lens shutter 26 may be opened and closed at a predetermined shutter speed. A normal format finder 2 is provided on the top of the camera body 10.
1, a large format finder 24 is removably attached. When this large-sized finder 27 is to be attached, the focus plate 20 must be lifted upward and removed in advance. The large-sized finder 27 is disassembled into an upper part 28 and a lower part 29, and a focusing plate 31 placed on a lower shoulder part 30 can be removed for replacement. This focus plate 31 is larger in size according to the screen size than the focus V-point plate 20' for normal format, and is arranged at a position optically conjugate with the large size film 23. Note that a lens is provided between the focus plate 31 and the reflecting mirror 11, and the focus plate 31
You can also lower the overall height of the viewfinder by moving the position downward. Further, although the large format finder 27 is at waist level, it may be at eye level.
In this way, when changing from the normal format size, which is the original screen size of the camera body 0, to the large format size, the normal format film back 13, the photographing lens 17, the fine... It is sufficient to remove the lens 21 and focus plate 20 from the camera body 10 and attach the large-format film back 22, photographic lens 25, and finder 27. Since the film surface of this large-format film back is located at the rear, away from the screen frame 13, a large-format photographic lens 25 with a long back focus can be used to obtain a large screen. Figures 3 and 4
The figure shows an embodiment in which a converter is attached to the regular format lens to lengthen the back focus instead of using a large format photographic lens.

That is, in the embodiment shown in FIG.
In the embodiment shown in FIG. 4, a converter 35 having a concave lens system 32 having a negative power as a whole is mounted in front of the converter 35 having a concave lens system 34 having a negative power.
is provided behind the normal format photographing lens 17.
When the converters 33 and 35 are used in combination in this manner, the normal format photographing lens 17 can be used as is in place of the large format photographing lens 25, resulting in low cost. In the above embodiment, the screen size can be changed in two stages, but more photographic lenses, finders, and film backs may be provided to allow the screen size to be changed in multiple stages.

According to the present invention having the above configuration, in addition to the normal format shooting lens, finder, and film back, a large format shooting lens, finder, and film back are provided, and depending on the purpose of photography, the lens can be used in place of the normal format shooting lens, finder, and film back. By attaching a large format camera, or a regular format camera instead of a large format camera body, to the same camera body, the screen size can be easily changed from regular format to large format, or from large format to regular format.

Furthermore, since the same camera body is used, it is possible to function as two cameras with different screen sizes at the lowest cost.

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing an embodiment with a normal screen size, Figure 2 is a side sectional view showing an embodiment with a large screen size, and Figures 3 and 4 are normal format photographic lenses. FIG. 3 is a side sectional view showing an embodiment in which a converter is attached to the lens to change it to a large-format photographic lens. 10... Camera body, 11... Reflector, 14... Regular size film, 15.
...Film back for regular format, 17...
Normal format photographing lens, 18...Lens shutter, 20...Normal format focusing plate, 21...
・Normal format finder, 22...Large format film back, 23...Large size film,
25...Large format photographic lens, 26...
Lens shutter, 27...Finder for large format, 31...Focus plate for large format. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A single-lens reflex camera body having a lens mount section on the front surface, a film bag mounting section on the rear surface, a viewfinder mounting section on the top surface, and a reflector disposed inside, which is mounted on the lens mounting section. A normal-format photographic lens, a large-format photographic lens with a lens shutter and a long focal length that is attached in place of the ordinary-format photographic lens, a regular-format film bag that is attached to the film bag mounting section, and this ordinary-format photographic lens. A large-format film bag is positioned behind the film position in the film bag, and a large-format film bag is installed in place of a regular-format film bag, and a normal-sized film bag is installed in the viewfinder mounting section. a large-format viewfinder which is attached in place of the normal-format viewfinder and has a distance from the reflecting mirror to the focusing plate longer than that of the normal-format viewfinder; , a single-lens reflex camera capable of changing the screen size, characterized in that the large-format photographic lens, film back, and viewfinder are attached to the single-lens reflex camera body in place of the viewfinder, thereby making it possible to change the screen size from normal format to large format. . 2. A single-lens reflex camera capable of changing the screen size according to claim 1, wherein the large-format photographing lens has a converter coupled to the front or rear of the normal-format photographing lens. 3. The screen size changeable device according to claim 1, characterized in that when the large-format viewfinder is attached, the normal-format focus plate provided above the camera body can be removed. Single-lens reflex camera.