British Kinematography (1950)

Record Details:

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November, 1950 SANDVIK AND VEAL \ FILMS FOR TELEVISION 157 image on Eastman Fine Grain Sound Recording Safety Film, Type 5373, or other similar types. This film offers the advantages of fine grain, low cost, adequate speed, and can be handled and processed under positive safelights to a negative at a lib control gamma of 0.60 to 0.70, as is ordinarily done for picture negative materials (Fig. 14). Composite release prints of sound and picture records can then be made on Eastman Fine Grain Release Positive Film, Type 7302. If a single copy record is desired, as would be required in theatre television, a negative tube image may be photographed directly on to Eastman Fine Grain Release Positive Safety Film, Type 5302 (35mm.) or 7302 (16mm.) or similar types, developed to a gamma of 2.2 to 2.5 in a positive-type developer, as shown in Fig. 16, and printed to a density that will give the best picture quality when projected on to a motion-picture screen. The presence of a sound track on a positive picture of this type poses considerable problems because of the necessity of using direct positive sound-tracks. Fig. 16. Typical H and D Curve of Eastman Fine Grain Release Positive Film, Type 7302. o o EASTMAN FINE GRAIN RELEASE POSITIVE FILM, 1 . I / 32 TYPE 7302 1/ if 2 8 24 2.0 " ft 2 48 i 6 i 2 06 // 04 OO • / 1 Log exposure Non-linearity Correction. It is most desirable in Kinescope recording to correct the non-linear characteristic of the Image Orthicon and the Kinescope being photographed. It will be assumed here that other circuits and components in a television chain are essentially linear compared with these two devices. There are two methods that have been used experimentally to compensate for this non-linearity. One is to build a correcting network in the form of a non-linear amplifier feeding the Kinescope. The amplifier would have the reverse characteristic of the apparatus to be corrected. This method has been tried, but the increased amplification causes considerable decrease in the signal-to-noise ratio. Another method is to incorporate the correction in the emulsion, by having a special emulsion with an upturning shoulder or a section of reverse curvature between the straight-line portion and the regular shoulder of the curve. When enough correction is incorporated into the emulsion, correct exposure becomes very critical. When correct exposure is obtained on the negative and a projection print is made, the print density becomes so high that upon projection back on to the television system, the available illumination is reduced so that the signal-to-noise ratio is decreased beyond acceptability, and the shading of