British Kinematography (1953)

August, 1953 NEW BRITISH STANDARDS 47 B.S. 586 : 1953 — Photo-electric cells for sound film apparatus. In 1935 the British Standards Institution first issued B.S. 586 for photo-electric cells of the emission type for sound film apparatus. One of the primary objects of that standard was to establish a simplified range of four cells from the great variety of sizes and types which were then in use. Unfortunately the standard sizes then chosen did not meet with universal acceptance and cells still have to be manufactured in a wide variety of types to meet the needs of individual equipment manufacturers. The B.S.I, has accordingly given careful consideration to the revision of this standard, and a revised edition has recently been published. This present edition, similar to that of 1935, relates solely to cells for use in sound film apparatus. The specified performance characteristics of the cells have been brought into accord with present day requirements, and anode voltage, sensitivity, dark current, variation in frequency response, gas factor, stability, and noise current are specified. A code system of symbols for designating the cell size, type of basing, and spectral response, is included. Owing to the great variety of sizes and types of cells already in use, the dimensional unification of cells necessarily presents very considerable difficulties. The B.S.I. Committee has, however, made a close study of the many existing cells and has made a selection of four sizes of cells, with associated types of basing, which are now put forward in this present edition of the standard. It is appreciated that the design of a sound head may not always permit of ready alteration, and that for some considerable time it will be necessary for many types of cells to continue for replacement purposes. Nevertheless, in order to promote economic production and to facilitate rapid replacement, the B.S.I, most strongly urges that wherever possible, existing apparatus be modified to accept one of the cells now recommended, and that all new apparatus should be designed for the use of these cells. Considerable importance is attached to the correct use of terms associated with photo-electric cells. A more extensive series of definitions is now included which will materially assist in a correct understanding of the terms used. Copies of these British Standards are obtainable from the British Standards Institution, Standards House 2 Park Street, London, W.\. FOR LIBRARIES LABORATORIES CUTTING ROOMS AND WHEREVER FILM IS BEING USED— User ft CONTINUOUS SPEED VARIATION FROM MAX. TO MIN. ft INSTANT STOPPING WITHOUT FILM STRAIN • INSTANT REVERSING Photograph by the " THE « SPEEDIVINDER" provides ft ADJUSTABLE FILM TENSION AC/ DC 200 250 v. WEIGHTlONLY 23 LBS. BURGESS, LANE AND CO: 16mm. & 35mm. POWER REWINDERS BLOCK J, SUNLEIGH WORKS, SUNLEIGH ROAD, WEMBLEY. WEMBLEY 2378