The Cine Technician (1953-1956)

October, 1953 THE CINE-TECHNICIAN 127 A FILM TECHNICIANS NOTEBOOK Compiled by A. E. Jeakins "FREDERICK FOSTER, in a recent issue of the -* " American Cinematographer," deals with the new and improved emulsions developed by Eastman Kodak in connection with the Eastman colour process. Eastman Kodak now offers four different film materials which can be used in colour productions; either right through from the negative to release print, or in conjunction with existing colour motion picture processes. Three of these materials represent improvements over earlier Eastman colour films. The most acceptable systems for colour motion picture production require the use of intermediate steps in order to include special effects and to provide protection masters. The preferred method appears to be one employing black-and-white separation positives and an integral tripack colour inter-negative. For this Eastman Kodak has provided special film stocks. The key film is, of course, the negative. The new Eastman colour negative film, type 5248, is balanced for use with tungsten lighting at 3,200 deg. K. and requires no filters over lights or lens. It can also be used with daylight or carbon-arc illumination when a Wratten filter No. 85 is used on the camera lens. The emulsion speed is rated at about 24 A.S.A. for tungsten and 16 A.S.A. for daylight. In terms of footcandles, about 200 at f.2 are reckoned to be adequate. The new film is less grainy than the earlier type and the colour couplers have been improved to give a better blue rendition, which is also an advantage in printing as the processed film has a lower blue density. The new Eastman Colour Print Film, Type 5382 (35mm.) and Type 7382 (16mm.) is similar to the earlier product, but improvements have been made to provide better image sharpness. A new magenta coupler is also incorporated in this film which gives a better rendition of red hues. Printing of the colour negative on to Colour Print Film can be done with either subtractive type printers employing colour compensating filters, or with additive-type printers which utilise three filtered light beams (obtained from three separate sources or from a single source with beam-splitters). In either case the printer must be designed to permit adjustment of both the intensity and the colour balance of the light for each scene. Additive-type printers have been found to give the best results from the standpoint of good colour contrast and saturation. The sound track can be printed from conventional black-and-white sound negatives, either variable area or variable density. Better frequency response ABOVE DIAGRAM illustrates procedure for developing Eastman colour films, both negative and positive. Arrows 1 and 2 point to two important intermediate steps in the procedure— buffer which removes anti-halation backing, and sound track developer. is obtained if the sound track exposure is confined to the two top emulsion layers of the print film. When effects are to be included, black-and-white separation positives are made through appropriate filters on Eastman Panchromatic Separation Film Type 5216 on a printer fitted with register pins. These separations also provide protection against damage to the original or against fading of the dyes. Slight corrections for contrast and density variations in the original due to exposure and/or processing are also possible during this step. The separation positives are processed in a standard black-and-white negative bath, and printed on to a new type Colour Inter-negative Film (Type 5245) using a registering printer. This new film has slightly higher contrast characteristics than the film it supersedes, and so requires lower contrast separation positives. As with the Colour Negative, there is a better rendering of blue. The separate layers of the Colour Inter-negative are exposed through the appropriate separations using filter packs of the correct type. Processing of the Colour Negative, Colour Print and Colour Inter-negative Films is carried out in conventional type processing machines which provide for all the steps required. These include in addition to the washing steps, prebath for backing removal, colour development, first fixing bath, bleach, second fixing bath and wetting agent or stabilising bath. Processing of the Colour Internegative Film requires the same solutions as for the Colour Negative but a shorter development time is used. For the Colour Print Film a different colour developer solution is employed, other solutions are the same. Light Sou Light Source' Camera Filter* Filter Required Required 3200K Tungsten lar nps 1 or J None None "CP" lamps (appro . 33MKI 1 MR Type 170 Straw-colored ISO Amp H.I A such as Kodak Wratten No 85 Brigham Y-l MR Type 40 Florentine Class Kodak Wratten No. 85 40 Amp Duarc Daylight (Sunlight Plus None Kodak Wratten No 85 some Skylight) nly. since final color biUn cng w.ll de done in pun ing FILTERS recommended for use with Eastman colour negative 5248 when exposed under light sources of various types.