Kinematograph year book (1944)

British Production. 279 in the infra-red from 6,600 AU to 8,600 AU. A Weston speed rating of eight is approximately correct for an unscreened meter used in sunlight, and allows for exposure of the film through an 88A filter, which transmits very little of the visible spectrum. In order to facilitate the making of duplicate negatives for contact printing, fine grain duplicating panchromatic negative film, previously available in 35-mm form only, is now also made in Safety 16-mm size, perforated for sound or silent uses. Fine grain release positive, code No. 1302, now used extensively in the U.S.A. for release print purposes, will not be available in this country until the termination of the war. Salvage Of Film Waste. — -The iecoveiy of all film waste is not only of importance to the film trade but also is an essential in our war-time economy. Several well-known concerns have made this branch of salvage into a highly specialised industiy and their efforts in the past twelve months have resulted in record quantities of film residues, emulsion waste and silver being recovered for subsequent refuse. Among the firms who serve the trade efficiently in this direction are : — ■ John BettS & Sons, Ltd. — This well-known Midland firm has always specialised in photographic residues, from film junk and renter's reels to emulsion wastes, and the final bar of silver. Their main refinery, situated in Birmingham, is conveniently placed for receiving consignments of waste from all over the country, and within the Greater London area they have a regular collection service for hypo solution waste from the various laboratories. It is not as generally realised as it might be that the photographic industry is by far the largest user of celluloid and silver, and the firm's services to the Trade for the recovery of all film waste is now more important than ever. H. A. Gregory & Co., Ltd. — Notwithstanding present-day difficulties, this important concern continues its operations in the recovery of basic photographic waste materials for subsequent employment in many phases of the war effort. After treatment, the film base and the recovered silver are passed on to firms who use both material and metal in various Government contracts. Two other firms who do a considerable business in the handling of scrap and junk film for ultimate use for a variety of purposes are Lloyd's, of Christchurch, Hants, who deal in both nitrate and acetate in any condition ; and R. Arton's, Ltd., who possess eveiy facility for the treatment of junk film and salvage. PROCESS WORK MUCH of the credit of the high standard of our prints is due to the general application in the laboratories of modern sensitometric methods and the consequent successful balancing of picture quality with sound density. Maintenance of consistency in print quality is one of the main problems of laboratory practice. According to M. V. Hoare, who addressed the B.K.S. on this subject, the laboratory is faced with three problems : (1) The production of a negative of constant gamma ; (2) the holding of the gamma of different rolls of positive stock constant ; and (3) the holding constant of the densities of separate prints made on separate rolls of positive stock. Changes in the density of the negative can usually be offset by changes in printer light, and are relatively unimportant, provided they are recorded on a reasonably usable part of the negative curve. The first point is the maintenance of the sensitometer to a standard to avoid drift. It is essential that a standardised lamp be kept for calibration purposes only, since the lamp in use will gradually vary in light emission, and so give false readings. In use the lamp must be carefully and frequently checked with a voltmeter. The effect of varying the development time of a negative is to vary gamma. There is a tendency for the laboratory to develop a picture negative by eye to secure constant density, so enabling it to print on the same printer point ; but the prints will not match if the exposure has varied, and print quality suffers. Mr. Hoare emphasised the need of keeping