Journal of the Society of Motion Picture and Television Engineers (1950-1954)

II. Eastman Color Negative Safety Film, Type 5248 General Description The new color negative film is known as Eastman Color Negative Safety Film, Type 5248. It is a 35mm integraltripack, incorporated-coupler type film similar in structure to the previous Type 5247 Film, but balanced for use with tungsten (approximately 3200 K), rather than for daylight illumination. It can, of course, be used under daylight conditions or carbon-arc lighting with suitable filters. The structure of the film is shown in Plate I. It is composed essentially of three emulsions sensitive to blue, green and red light, respectively, and coated on a single safety film support. Between the blue and green-sensitive layers is a yellow filter layer which prevents blue light from reaching the bottom two emulsion layers, which are also blue-sensitive. The emulsion layers contain dye couplers dispersed within them so that, after exposure and processing, metallic silver and appropriate dye images are produced in each layer. The silver is later removed from the film, leaving the dye images. As in the case of the earlier Type 5247 Film, two of the couplers dispersed within the emulsion layers are themselves colored. The original color is discharged in proportion to the amount of image dye formed, and the remaining colored coupler serves as a mask to provide correction for unwanted absorption in the process dyes. The characteristics of these colored couplers are similar to those which have been described in previous papers.1-3 After processing, the color negative appears as shown in Plate II. Each area of the color negative is complementary in color to the corresponding area in the original scene and, as with other types of negatives, the light and dark tones of the negative are reversed with respect to those of the original subject. In addi tion to these characteristics, a prominent orange color is observed in all areas of the negative which have received little or no exposure, because of the color-correcting mask remaining in the emulsions. Characteristics Eastman Color Negative Film, Type 5248, is balanced for use with 3200 K tungsten illumination. Under these conditions, its speed is slightly less than that of Eastman Background-X Panchromatic Negative Film, Type 5230. Its contrast characteristics are suitable for use with the other materials discussed in this paper. The film is also adaptable for use with color systems employing other films and techniques than those described here. The exposure latitude is somewhat greater than that found for reversal color films. The graininess characteristics of Type 5248 Film are slightly better than those of the earlier Type 5247 Film. The correction for blue-light absorption provided by the colored couplers has also been modified so that blue subjects are not rendered abnormally bright in the reproduction, as was the case with the earlier film. This results in a lower blue-light density for the processed film. The individual emulsion layers of Eastman Color Negative Film, Type 5248, have keeping properties similar to those of black-and-white negative materials. However, in the case of integral-tripack color films the requirement of maintaining the original color balance must be fulfilled. The storage conditions are therefore slightly more critical than those used for black-and-white negative materials. For extended periods of storage, the film should be kept at temperatures not exceeding 55 F in order to minimize color-balance changes. Regulation of humidity is not important as long as the film remains in the unopened, original, taped can. Ample 670 December 1953 Journal of the SMPTE Vol. 61