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XIV. DUPLICATION OF TRI-PACK COLOR FILMS
No. 6
s£ /No5
i i i i
400
500 600
WAVELENGTH, m/z
700
Fig. 120. Transmittance vs. wavelength characteristics of developed unexposed Kodachrome. No. 5 is
EK 5265 duplicating film, No. 6 is EK 5264 type A film.
Data for Kodachrome Duplicating Film. The film itself can be checked for deviations from the " ideal." Figure 120 shows a per cent transmittance versus wave length characteristic of unexposed developed Kodachrome; for comparison purposes both Type A and duplicating Kodachrome are shown. From these curves it is reasonable to conclude that Kodachrome when unexposed provides a satisfactory neutral gray.
The film can next be checked under simulated operating conditions. Figure 121 shows these characteristics when a fine-grain black-and-white film which is uniformly exposed (EK 5365 exposed and developed to a density of 0.5) is printed on a step-contact printer through the basic set of filters recommended by Eastman Kodak for duplication. These curves show that at the exposure used the neutral gray is reasonably well maintained. In addition, they indicate that although EK 5264 Type A Kodachrome requires less exposure than EK 5265 duplicating Kodachrome, the duplicating film has the smoother curve and should be used whereever possible. Among other reasons for preferring it, is the not unimportant factor that the price is appreciably lower.
Contrast Control. It may well be said that integral tri-pack duplication makes no provision for the purposeful control of contrast. While it
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500 600
WAVELENGTH, m^
700
Fig. 121. Transmittance vs. wavelength characteristics for Kodachrome duplication of black-andwhite film. EK 5365 was uniformly exposed and developed to a density of 0.5; this was printed on EK 5265 (No. 1), and on EK 5264 (No. 2). Lamp at approx. 80 v. (See Fig. 122 for lamp data.)