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.OLD TYPE
Sulfide Developer
MODIFIED^ Sulfide Developer^
LOG E Fig. 1. Sensitometric effect of modified silver sulfide developer.
layers are sensitized to respond principally to three different colors of light. Third, the speed relationships of the layers are determined by the characteristics desired for the dye formation for pictures while sound-track development converts the halides in all layers to silver sulfide, a much different material.
Sound tracks on Kodachrome films are usually printed using a conventional sound printer with adjustments of the printer lamp current to obtain a particular density. Changing the printer lamp current results in the simultaneous change of both the intensity and the color quality of the light source. Since the efficiency of different optical systems varies considerably, and since many different types of lamps and heat absorbers are in use, it is almost impossible to give any information, such as a filter balance, which can be applied without further extensive tests on the particular equipment involved.
Standardizing the light source for sound-track printing requires very little additional control work for most laboratories and makes possible the use of print
ing recommendations without extensive tests. If conventional distortion tests can be made, there is still a considerable saving of time and film because an excellent starting place is available for adjusting the exposure balance for particular equipment. Should emulsion changes become necessary or desirable, the extent of filter-pack modification could be specified, reducing appreciably the need of additional time and filmconsuming tests.
A fixed color temperature of 2900 K for a tungsten source is suggested because it is well within the rating of most lamps and because experience has indicated that more than enough light is available on almost any printer. Heatabsorbing glasses may greatly modify the spectral energy distribution of the light source. Heat-absorbing glasses should be Pittsburgh 2043, 2 mm thick or an equivalent filter. Adjustments of intensity are made by neutral density filters or diaphragms or both, depending on the particular printer. The final adjustment of color quality is made with Kodak Color Compensating Filters, but
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August 1952 Journal of the SMPTE Vol. 59