The Cine Technician (1953-1956)

Jan. -Feb., 1953 THE CINE-TECHNICIAN tained by the laboratory. It may well be felt by cameramen that these gadgets are simply a means of increasing the footage shot for the laboratory and a routine which consumes valuable time on the floor, but both of them are essential to the laboratory and can save a good deal of print footage in the long run. The charts required are a register and resolution chart and grey scale combined and a device which has come to be called a lily. The register chart should be shot at the start of each day's work and once for each fresh magazine. The lily must be photographed at the end of every scene. The register chart, with its clearly marked indices at fixed distances, makes the measurement of any lack of register between the three negatives quick and easy to perform. The resolution chart makes it easy to check the bipack contact; the grey scale provides a rough test of the relative contrast of the three negatives. The lily provides the standard white area mentioned earlier, which is used in grading. The lily must, of course, be photographed under lighting conditions which are typical for the scene it represents and not in shadow. It must be close enough to the camera to give an area on the negative large enough to enable density measurements to be made without difficulty and if any effects filters, such as a 78A for night effects, are being used over the lamps or the lens the lily must be shot with the filters off. The short length of film which includes the lily, say 10 to 20 feet, should consist of half with the lily in frame and half a straightforward shot of the scene to which it refers with the actors, if any, in an average grouping. After development of the negative all these reference scenes are cut from the roll and joined up into a separate roll of their own for grading and printing. In this way an idea of the general balance of the scenes can be obtained and the actual film can be canned up, when the reference scenes have been cut out, and not again handled until final cutting of the picture. In addition this procedure enables the grading, lighting and register of the scenes to be checked with the minimum expenditure of print footage. Laboratory Processing and Control Three-strip materials can be processed in just the same way as normal black and white negative materials, with only one or two minor reservations. First their contrast must be fixed by the print process being used, but unless an unusual release material such as Dupont 875 is being used, an effort should be made to develop them to the gammas they were designed for, that is, in the range 0.65 to 0.70. In exposing the IIB sensitometer strips the green record can be exposed to white light, filtered with the Aero 2 emulsion down in the usual way. The bipack is exposed to white light but as a bipack, that is with the base side of the front film to the light source and with the rear film emulsion down on top of it. If a visual densitometer is used to plot the strips the red dye of the front film must be cleared first, but with a photo-electric densitometer such as the Western Electric RA-1100B there is no need to do this. In cases where exposure is necessarily on the low side the record which will show the under-exposure worst is the blue. This is especially the case when incandescent light is used since even with the fastest blue sensitive emulsion the lack of blue in tungsten lighting makes it difficult to achieve a blue record which is as well exposed as the other two. With the British Tricolour camera for processing the blue record only a special developer A typical three-strip colour camera, the British Tricolour, showing the two separate magazines, one for the two films of the bipack and the second, single film, magazine which gave a useful increase in effective emulsion speed was worked out by Keith M. Hornsby; it has the following formula: Metol 200gm. Hydroquinone 500 gm. Sodium Sulphite (Anhyd.) 100 kgm. Sodium Carbonate (Anhyd.) 10 kgm. Water to 1.000 Litres The principal difficulty with developers of this type is that they are rather wasteful of chemicals since they need to be boosted quite heavily (with the same formula as a replenisher) in order to keep the bromide concentration low and the emulsion speed high. The high alkali concentration gives the maximum speed in the lower negative densities, while the low concentration of developing agents keeps down the densities produced at the higher exposure levels. An alternative approach to this problem of the poor exposure of the blue record is to use latensification, a procedure which is receiving a good deal of attention nowadays in black and white work. It has also been used for a good many years by Cinecolor for bipack negatives. Some very useful research on methods of latensification was done over ten years ago by G. S. Moore, of llford, and all the practical details needed for this process are given in the Photographic Journal, Jan. 1941, p. 27, and Nov. 1948, p. 239. This method of increasing the speed of motion picture film is a very useful one, since it is not too difficult to carry out, is fairly easily controllable, and gives roughly double the effective emulsion speed. The red dye which is incorporated into the emulsion on the blue record is a serious nuisance to the laboratory since its removal is not easy and is a decidedly smelly operation with some risk of emulsion damage due to softening and extra handling. A saturated solution of sodium hydrosulphite is usually used for this dye removal and this can be incorporated as an extra tank on the processing machine or as a separate smaller processing machine. We prefer the latter method since the dye