GB664818A - Photo electric exposure meter - Google Patents

Abstract

664,818. Photo-electric exposure meters. SOC. MAROCAINE D'ACHATS & DE CONSTRUCTIONS SOMARAC. Dec. 31, 1947 [Nov. 28, 1946], No. 35408/47. Class 40 (iii). [Also in Group XX] A photo-electric exposure meter has a plurality of easily removable and interchangeable dials, each dial corresponding to a different emulsion speed and carrying graduations associating diaphragm openings and shutter speeds for the given emulsion speed, whereby the correct diaphragm opening and shutter speed can be read off directly, immediately the light intensity reflected by the subject is measured by the photo-electric cell. As shown, the dial is printed on a sheet 5 inserted into the body 1 of a photo-electric exposure meter along guideways 6 and located by stops 11. The pointer is observed through a window 3. A part 7 of the body 1 is cut away so that a projection 8 of the sheet 5 may be gripped for removal. A set of dials may be prepared bearing (preferably on both sides) scales for one or more emulsion speeds, which may take the form of concentric arcs corresponding to shutter speeds and' graduated in diaphragm apertures, or vice versa, or two sets of intersecting curves indicating shutter speeds and diaphragm apertures respectively. Separate dials may also be prepared for instantaneous and time exposures, or a dial for short exposures may have a supplementary arbitrary scale of light values, from which longer exposures may be calculated. Each dial may be rotatable through a small angle to bring into use one of two scales inscribed side-by-side. The Specification as open to inspection under Sect. 91 states that the dials may be opaque or transparent, and also describes a meter with two dials inscribed on a strip pivoted to the case, and a meter with dials carried by a long strip wound and unwound between drums, with registration marks on the strip and on the meter case. This subject-matter does not appear in the Specification as accepted.