GB860165A - Improvements relating to photographic methods and apparatus - Google Patents

Abstract

860,165. Photographic methods and apparatus. INTERNATIONAL POLAROID CORPORATION. June 21, 1957 [Nov. 28, 1956], No. 19570/57. Classes 98(1) and 98(2) Two photographic prints are produced by the silver halide transfer reversal process using emulsions of the same ASA rated speed but exposures of different magnitude and are processed with different compositions so as ASA equivalent overall speeds appropriate for the different exposures. Thus the exposures may be made with little or no adjustment of diaphragm or shutter setting and processing compositions selected to produce the prints independently of these factors but in accordance with the luminance of the subjects. Seven such compositions are detailed using metol-hydroquinone for exposures corresponding to 25 to 50 reciprocal metre seconds, changing to amidolhydroquinone and then amidol alone for increasing reciprocal metre seconds, together with varying proportions of hypo but constant proportions of sodium sulphite hydrate and carboxymethyl cellulose. Cameras and rupturable containers for the compositions which may be inserted into the cameras after exposure are described and illustrated, thus in Fig. 1 an assemblage 28 having sheels 30, 32 for emulsion and image reception respectively are inserted through gap 48 to take positions in exposure and storage chambers 40, 38 of the camera, and container 50 with the selected composition is endwise inserted into chamber 44 between the sheets after exposure; withdrawal of the assemblage 28 by end portions at the lower left of the figure then causes rupture of the container and spreading of its composition therebetween to effect the processing, the sheets having opaque backs to prevent unwanted light action. Of other Figures, not shown, Fig. 5 is like Fig.1 but has provision for eight of the assemblages, Fig. 6 is for a simple roll film camera and Fig. 7 a roll film camera including a light-sealed imbibition chamber to accommodate the assemblage during processing; and other Figures are concerned with the matters of insertion and operation of the container within the camera. Specifications 684,991, 794,312 and 835,767 are referred to.