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

different from that of Type 843, but it is similar to that of the Color Positive Film Type 848, as shown in Fig. 9. In order to produce dupe negatives with fine grain and good resolution, the emulsions used for this film type are much slower. The exposure index is approximately 0.6 to 1.0. This film type is also on gray base of the density of the Negative Type 843 so that it can be readily interspliced with it. The resolving power is approximately 66 lines/mm. The sensitometric characteristics of the color dupe negative film are shown in Fig. 7. The color dupe negative film is used to make color negative dupes from tricolor separation positives made from the color negative originals. Optical effects, fades, lap dissolves and other special effects can be introduced via these color dupe negatives. The various methods which can be used to obtain a color positive release print will be described later, below. An sco Color Positive Release Printing Film, Type 848 Film Characteristics: In emulsion layer arrangement the color positive release printing film is similar to the color negative film shown in Fig. 1. The color positive film can be exposed either directly from color negative originals, from color negative dupes or from blackand-white tricolor separation negatives. The sensitometric curves of the individual layers of the color positive film, plotted as integral densities, are shown in Fig. 8. In Fig. 9 the spectral sensitivity of the color positive printing film is illustrated. Good separation of the spectral sensitivity ranges with a minimum of overlaps is desirable for good color reproduction in the printing film. Dye Absorption: The absorption characteristics of the dyes produced in the color positive film are different from those in the color negative and dupe negative film. The absorption maxima are: 440 rm* for the yellow layer, 540 m/u for the magenta layer, and 660 in/z for the cyan layer. Film Speed and Resolving Power: The sensitivity of the color positive film is similar to black-and-white positive, approximately exposure index 1.5. The resolving power is 64—66 lines/mm. All three color film types used in the Ansco Color Negative-Positive Process are on low-shrink, safety base. Color Processing Procedures and Solutions The three color film types used in the process require very similar processing steps and processing solutions. Only the Color Negative Film, Type 843, requires a different color developing solution. The color dupe negative film and the color positive release printing film can be developed in the same solutions throughout. The color developing time of these two types is different, as shown in Table I. For uniform processing of all types of color film materials good control of the processing solutions at all times is very important. Basic control procedures which apply also to the handling of color negative-positive have been described by Bates and Runyan,5 while analytical procedures to control and maintain solution strength and uniformity have been presented by Brunner, Means and Zappert.6 General information in regard to color sensitometry may be found in the report of the SMPTE Color Sensitometry Subcommittee.7 Methods of Release Printing From Ansco Color Negatives Methods of release printing from Ansco color negatives for the printing of Ansco color negative originals from different methods and certain variations thereof can be used to produce color positive release prints. These methods are summarized in Fig. 10. Not all of these methods are equal in regard to color quality and cost. A more detailed discussion of the ad 470 June 1952 Journal of the SMPTE Vol. 58