GB2032122A - Camera - Google Patents

Abstract

A camera has a front part 1, with lens 2, shutter 3, light sensor 4 and seal 5, and at least two interchangeable rear parts 7 and 12, with seal 6 and gate-masking slider 9, for housing a roll film (Fig. 2) and instant picture cassette (Fig. 3), respectively. As shown part 12 has a supplementary negative lens 16. A supplementary positive lens may alternatively be arranged in front of lens 2. Further, slider 9 may be dispensed with (provided that partially exposed film is changed in the dark). <IMAGE>

Description

SPECIFICATION Improvements in and relating to photographic cameras The invention relates to a photographic camera consisting of a front part having a tens, and at least two interchangeable rear parts for accommodating record carriers of different formats.

Such cameras are well known for studio cameras and medium-format cameras. The various formats of the rear parts can be compensated for as may be desired by changing the lens. In the case of fixed lenses, only a part of the image field of the lens designed for the larger format is used for the smaller format, which results in a narrowing of the field and thus in a socalled telephoto effect. Fixed lenses, provided their covering power is sufficiently large, can also be used with larger formats, but that leads to a wideangle effect. The latter possibility is also not generally used because the increased expense for a lens having a large covering power of which normally only a part is used, is not regarded as justifiable.

It is an object of the invention to provide a camera of the kind referred to above mentioned at the beginning in which, with different rear parts, photograph formats of various sizes can be selected, but in which the field remains approximately the same.

According to the invention this is achieved by arranging on at least one rear part an optical accessory that cooperates with the lens located in the front part and adapts the focal length, back focus and image field thereof to the picture format to be used.

One form of camera constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic perspective view of the front part of the camera; Fig. 2 is a diagrammatic perspective view of a rear part for a small-format record carrier; Fig. 3 is a diagrammatic perspective view of a rear part for a large-format record carrier; Fig. 4 is a diagrammatic side view of the front part of the camera with the case partially cut away; Fig. 5 is a diagrammatic side view, partly in axial cross-section, of the rear part shown in Fig.

2; Fig. 6 is a diagrammatic side view, partly in axial cross-section, of the rear part shown in Fig.

3.

Referring to the accompanying drawings, the front part of the camera shown in Figs. 1 and 4 comprises a case 1 having a lens 2 of short focal length, for example, 45 mm, fitted in it, a shutter 3, if desired an additional diaphragm, and an exposure control arrangement 4 having a light receiver facing forwards. The case 1 is provided with one part of a light-excluding labyrinth seal 5.

The rear part shown in Figs. 2 and 5, which is for the smaller format, consists of a case 7, which has at its front the counterpart 6 of the labyrinth part 5 and which, in a manner known per se, is equipped with a small-format record carrier 10 which can be advanced by means of an advancing knob 8. Furthermore, the case 7 advantageously has other known features that are not shown, such as, for example, a film counter, a device for sensing a marking on the inserted film that indicates its film speed and a device for passing this information to the exposure control facility 4 of the front part, and also a back cover that has to be opened to insert the film. The film-advancing knob 8 may be replaced by more complicated known advancing mechanisms. Furthermore, the picture-gate 11 is masked in known manner by a slider member 9.

The rear part for the larger format, which shown in Figs. 3 and 6 likewise consists of a case 1 2 having a labyrinth counterpart 6 on its front side and a picture gate opening 11 that is masked by a slider 9. The rear region can receive an instant picture cassette 13 and contains two developing rollers 14 and 1 5 and the associated advancing mechanisms, which are known per se and which are not shown.

Furthermore, behind the picture gate 11 there is arranged a diverging or negative optical element 1 6 which, together with the lens 2 of the front part 1 when the two have been put together, forms a lens that provides the entire image field of the instant picture film in the cassette 1 3 with a focussed image and with the normal field of view.

The focal length of the composite lens formed is, approximately, of the order of three times the focal length of the lens 2 of the front part 1.

The manner of operation of the camera is as follows: The user inserts suitable films in the two rear parts. He then attaches the front part 1 to the rear part with which he wishes to take photographs.

He then removes the slider 9 in that rear part. If he wishes to take photographs with the other rear part, he interchanges it with appropriaNe actuation of the slider 9 in each rear part.

In a simplified form of the camera, the slider 9 can be dispensed with. However, exchange of one rear part for another when the film has been partially exposed is then no longer possible without losing the pictures, unless the exchange is carried out in the dark.

The lens 2 can also be designed to have a long focal length, the negative optical element 1 6 in the large-format attachment then being unnecessary. However, a positive or converging element then has to be arranged in a barrel in front of the small-format attachment so that the positive element, together with the lens 2, forms a lens system of short focal length.

Furthermore, it is possible, of course, for the large-format attachment 1 2 to be designed for use with sheet film, roll film or other large-format record carriers instead of instant picture films, or for the small-format attachment 7 to be designed for use with different types of film.

An advantage of the invention is that it offeros an opportunity of producing with very little expense for the average consumer a camera system that was previously only available to professional photographers, owing to the fact that only a single front part, which is relatively complicated, is required. There are the added advantages that the size and weight of the equipment is reduced.

Claims (5)

1. A photographic camera comprising a front part having a lens and at least two interchangeable rear parts for accommodating record supports of different formats, wherein on at least one rear part there is arranged optical means which is arranged to co-operate with the lens located on the front part and adapts the focal length, back focus and covering power of the lens to the picture format to be used.

2. A photographic camera as claimed in claim 1, wherein the optical means is arranged on a rear part that is not intended for the smaller or smallest format, is diverging and, together with the lens of the front part, forms a system having an increased focal length, an increased back focus and enlarged covering power as compared with the lens of the front part taken by itself.

3. A photographic camera as claimed in claim 1, wherein the optical means is arranged on the rear part intended for the smaller or smallest format, is converging and, together with the lens of the front part, forms a system having a reduced focal length and a reduced back focus as compared with the lens of the front part taken by itself.

4. A photographic camera as claimed in any one of claims 1 to 3, wherein the rear part for the larger format, or one of the larger formats, has an arrangement for accommodating instant picture films and initiating the development thereof.

5. A photographic camera substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.