The Cine Technician (1939)

V2$ THE CINE-TECHNICIAN Aug. -Sept., 1937 German specification, No. 632,695, proposes the production of a four-colour image on lenticular stock, by coating it with two emulsion layers, sensitive respectively to the long and short wave-lengths, and using a double filter. Advantages claimed are easier printing, a less loss of light in projection, and the possibility of using finer lenticulations. In a method of printing lenticular films, described in No. 457,656, the elementary beams emanating from the original film are explored successively by a copying optical system of small aperture, and one film is moved so that the image will remain stationary. A modification of this principle is described in No. 458,418. Subtractive Processes Judging by patent specifications, subtractive processes are engaging the attention of research workers more than additive processes. Dr. Bela Caspar points out in Nos. 458,256 and 458,304 that it is useless to sensitize a photographic emulsion for specific light rays if the layer is uniformly dyed by means of a dye-stuff which absorbs this light ; he proposes incorporating a coarsely dispersed dye-stuff and after exposure, converting it to a finely distributed form. Kodak give in No. 458,664 formulae for colour-forming developers, comprising an aromatic amina developing agent and a colour coupler consisting of an organic compound with a reactive methylene group. No. 458,665 relates to a similar developer and a colour coupler consisting of a hydroxy! diphenyl. In U.S. patent No. 2,059,887 (assigned to Kodak) are described various methods for controlling the penetration of the colour baths in a multi-layer film, such methods including adding inert substances to the bath, the use of stop baths, and drying temperature, and hardness control. No. 453, 674 refers to two disadvantages of existing methods of producing a dye image by the destruction of dyestuffs in areas containing a silver image ; first, the necessity of printing from a positive, and secondly, that variations in thickness of the emulsion give rise to corresponding variations in densitv of the dye image. A multi-layer system is described embodying a reversal process. Agfa state in No. 454,788 that fine-grained emulsions, rich in silver, have a particularly high special sensitization ; the use of such emulsions without filters is proposed for a tripack film. No. 455,556 refers to the fact that dye contained in emulsions must be in a very finely dispersed condition, and proposes dispersing the dye in gelatine with the aid of a wetting agent. Kinematograph Weekly, June 3rd, 1937. Microphone Mixers. By M. Rettinger. The article discusses the design of compensated microphone mixer circuits, in which the impedance matching is achieved by the inclusion of a series compensating impedance in the microphone circuit. General equations are obtained for multi-channel mixers of both the parallel and series-parallel type. These equations determine the values of the compensating impedance, the load impedance and the insertion loss in decibels in terms of the source impedance and the number of groups. S.M.P.E. Journal, June, 1937. Eastman Fine Grain Duplicating Films The active co-operation of the Kodak Company with the Motion Picture Industry has been of major importance in the solution of many problems concerning motion picture technique. Recently, considerable study has been given to the important problem of duplicating, culminating in the introduction of two new products, comprising a Fine Grain Duplicating Positive Film and a Panchromatic Fine Grain Duplicating Negative material, emulsions 1365 and 1203 respectively. When properly handled, these two new duplicating films will produce a negative of excellent photographic quality, practically indistinguishible from that of the original negative, but the method of handling these prodin tdiffers so considerably from that recommended when using Eastman Lavender Duplicating Positive and Eastman Duplicating Negative materials, that the following general description of these two new films, together with some instructions on their use will, we hope, be helpful. Emulsion 1365, the Fine Grain Duplicating Positive Film, is very much slower in speed than is Eastman Lavender Duplicating Positive. It can be handled safelv under the Wratten Serie < »A Safe-lights. Due to its extremely low speed, it is not possible to obtain sufficient exposure when printing on the normal printer light scale, and it becomes necessary to run the printer at a lower speed than is normally used. While the actual printing speed required depends upon the intensity of the light source and other factors, it may be helpful in estimating exposure requirements if an example in actual practice is given. Under laboratory conditions it was found that using an average density negative in a contact printer running at 14 feet per minute and equipped with a 500-watt, 110-volt monoplane filament projection type lamp, located at a distance of ten inches from the printing gate, operated at 110 volts, a satisfactorily exposed negative was obtained. It is recommended that exposure should be so adjusted as to give a minimum density of 0'60 to 065, so as to utilize the region of exact tone reproduction for the important tones of the picture. The development process should be carried out in the Borax D.76 developer. Under normal conditions of machine development, the desirable gamma value of between 1*10 and 130 is obtained in four to five minutes at 65 deg. F. In this connection, when making sensitometric exposures on the Eastman type 2B. Sensitometer, using the 1365 type film, a more satisfactory curve is obtained if a double exposure is given. The Fine Grain Duplicating Negative 1203 is a panchromatic negative and must be handled under Wratten Series III indirect room lights. If greater illumination than this is required, a sheet of tissue paper may be substituted for the regular weight white paper in this safelight filter. While 1203 film is slower than the normal Eastman Duplicating Negative, it is not slower to the same extent as is the Fine Grain Duplicating Positive compared with Lavender Duplicating Positive, and little trouble should be experienced in printing this film. The 1203 film has a higher rate of development than the normal Duplicating Negative material and under normal conditions of machine development, using a D.76 type of developer at 65 deg. F., a gamma value of between 060 and 0*70 will be obtained in between four and five minutes. When making sensitometric strips on this film, the positive set-up of the Type 2B. Sensitometer should be used. Both these new materials are now being used extensively in motion picture laboratories in Hollywood and New York and remarkable results are being obtained. Technical Service, Motion Picture Film Dept., Kodak 1 til