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STRAIGHT LINE AND TOE RECORDS
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Values of printing coefficient ranging from 1.0 to 1.4 have been found. The printing coefficient is the ratio of gradations of effective printing densities to gradations of visual diffuse densities of the negative. Admitting the possibility of reflections from the negative in the printer which differ from those occuring in the visual diffuse densitometer, we can write:
Effective printing density = A -f (visual density X P.C.)
The effect of the constant A is a shift parallel to the density axis without change of shape, and thus is equivalent to a change in light intensity in the printer lamp. The P.C. for the sound negative bath which produced Fig. 1 was 1.2; the effecting printing gamma then was 0.60.
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H &. D CURVE y = 2.0
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E. K. POS. CINE FILM
DAYLIGHT TIME SCALE (MACHINE DEVELOPED)
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LOG. NEG. EXP • METER-CANDLE-SECONDS
Fig. 2. Composite print development.
Fig. 2 exhibits the H & D curve of gamma 2.0; it is an Eastman time scale strip developed at the Fox Laboratory in Hollywood in the positive bath which serves for the sound negative and for the Movietone print. The printing coefficient of the negative was found to be 1.2. The method of determining P.C. is described in connection with the next figure.
Fig. 3 is a plot of print visual density vs. negative visual density in the Fox processing. A negative sensitometer strip, the visual densities of which were carefully measured, was spliced into a loop of clear film and printed at printer points 3, 6, 9, 12, 15, and 18. Prints made with the 60-watt lamp with no filter at points 6, 12, and 18 are represented in Fig. 3. Similar prints obtained with No. 39 filter and a ground glass gave curves of the same shape. The net effect of the filter and ground glass is to reduce the light; the change in printing coefficient due to the filter is offset by the reduction in print gamma due to the change in light quality.