GB453845A - Improvements in and relating to apparatus for light control in photographic apparatus - Google Patents

Abstract

453,845. Photographic exposure] meters. RISZDORFER, O., 1, Gellerthegy-utca, Ungarn, Budapest. March 18, 1935, No. 8345. Convention date, March 16, 1934. [Class 98 (i)] In photographic apparatus, the light falling on a light-sensitive device passes through slots or apertures in two or more screens, each of which is movable with respect to the other or others in accordance with an independent variable. As shown, a photo-electric cell 12 is placed behind two overlapping screens 13, 14. Radial slots 15 each of different width are provided in the screen 13 and the screen 14 contains three peripheral slots 16 of tapering shape. The screens are moved under the action of factors influencing the exposure such as shutter speed and diaphragm aperture, and control the size of the opening in front of the cell 12. Other factors such as the sensitivity of the emulsion may be taken into account by using light filters. The peripheral slots may be of constant width. In a modification two wedge-shaped slots are arranged at an angle to each other in two screens which are movable in accordance with the exposure variables. The Specification as open to inspection under Sect. 91 comprises also the use of grey wedges instead of slotted screens. Other photo-electric apparatus is described and includes an objective lens in which the photocell surrounds the lens in annular form, a screen of resilient material, e.g. rubber, textile fabric, preventing the effect of light arriving from a lateral direction. In apparatus shown in Fig. 22 (Cancelled), the photo cell 143, the objective lens tube 145, and the finder 146 are mounted on a common base plate 147, which is affixed to the casing 148 of photographic apparatus by a bayonet lock. Two coils 149, 150 fed by the photo electric current are mounted between the poles of magnets 151, 152, and carry at the end of levers 153, 154, two screening members 155, 156 which form a rectangular aperture 157 in front of the objective lens. In front of the cell 143 is mounted a diaphragm 160 coupled to one of the exposure variables. The aperture 157 is varied in accordance with the illumination, by movement of the screens 155, 156 in a vertical direction. The axis of the coils may be vertical and furnish a horizontal movement for the screens. In a modification three coils operate three screens to give an adjustable hexagonal aperture. In apparatus shown in Fig. 25 (Cancelled), the pointer 177 of the instrument 176 measuring the photo electric current is viewed by a double mirror arrangement 179, 181 through the usual finder arrangement 182, 183. The pointer may be horizontal or vertical, and the casing for the mirrors may be folded down. The Specification also describes the subject matter of Specifications 416,294, 454,296, 454,297, and 454,299. This subjectmatter does not appear in the Specification as accepted.