Ansco Color Release Film, type 732
Subtractive 3 color: Chromogenic monopack
(Ansco Division of General Aniline and Film Corporation)
Original Technical Papers and Primary Sources
Duerr, H. H.; Harsh, H. C. (1946): Ansco Color for Professional Motion Pictures. In: Journal of the Society of Motion Picture Engineers, 46,5, pp. 357-367.
“Ansco Color for Professional Motion Pictures*
H. H. Duerr and H. C. Harsh**
Summary – The 3 new Ansco Color Films which are designed for producing full color million picture release prints are described. These films are (1) Ansco Color Type 735 (Camera Film), (2) Ansco Color Type 132 (Duplicating Film), and (3) Ansco Color Type 732 (Release Film). Methods for making second generation dupes, special effects, lap dissolves, etc., are discussed, and the procedure for printing sound tracks is outlined.
The basic principles of the Ansco Color process have been described previously. We will, therefore, limit the discussion of these principles to a brief review of the fundamentals of the process so far as they are necessary for the proper understanding of the application of Ansco Color to motion picture production.
The Ansco Color process is an integral subtractive color process using the method of dye coupling for the production of dye images in a multilayer material. Colorless color-forming components are incorporated in the emulsion layers. It is the unique and very important property of the color-formers in the Ansco Color process that they are of a molecular structure which renders them nondiffusing. The color-formers are immobilized in their respective emulsion layers and do not bleed into adjoining layers.
The layer arrangement of Ansco Color Reversible Film is shown in Fig. 1a and 1b. The film base, which can be either cellulose nitrate or acetate, carries an antihalation layer, followed by the red-sensitive emulsion layer. This emulsion layer also contains a colorless dye-forming component which, upon development in a suitable color developer, develops an image in color, complementary to the color sensitivity of the layer. In the case of the red-sensitive emulsion layer, the color is blue-green or cyan. For reasons of simplicity, this layer is usually referred to as the “cyan” layer.
The green-sensitive middle layer contains a color-former which, upon development, produces a magenta image, therefore called “magenta” layer. A yellow filter layer, coated on top of the magenta layer, absorbs all blue light, which would normally affect also the cyan and magenta layer, and therefore has to be filtered out in order to obtain the desired separation of color in these layers. The top emulsion layer is blue-sensitive only and the nondiffusing color-former in this layer develops to a yellow image. This layer will be referred to as the “yellow” layer.
The dye formers or color-formers in all 3 layers have been carefully selected so that they develop to a cyan, magenta, and yellow color, respectively, in one color developing step. This greatly simplifies the processing of Ansco Color Film and makes it possible to have the complete processing done by the consumer with developing equipment which is very similar to that regularly used for black-and-white reversible development.
The fundamental principles of the Ansco Color process are applicable to a great variety of color products. Ansco Color Reversible Film for daylight and tungsten light has been in use for some time in the form of 16-mm and sheet film. These materials are being manufactured for use primarily for direct projection and, therefore, have gradation characteristics which make them particularly well suited for this purpose. These film types, however, are not very satisfactory for the motion picture industry, where the requirements are essentially different. The most important requirement for a color transparency suitable for 35-mm motion pictures is that it lends itself to the printing of first and second generation duplicates with a minimum loss in color brilliance and fidelity.
These considerations call for a camera film which is quite different in gradation, color balance and other characteristics from the regular Ansco Color Film. Ansco Color Type 735 is the new film material designed and developed to meet these specific requirements of the motion picture industry.
Fundamentally, Ansco Color Type 735 is quite similar to the regular Ansco Color Film and the layer arrangement is the same as shown in Fig. 1a. It differs from this film primarily in that the gradation is considerably softer, the grain is finer, and the color balance is purposely slightly off-neutral. Fig. 2 shows a comparison of the H and D curves of Ansco Color Type 735 and the regular Ansco Color Daylight Film Type 235. This new material is designed to provide a film for exposure in the camera which is ideally suited for making release prints on Ansco Color Release Film Type 732. Ansco Color Type 735 is not intended for projection and its use in motion picture practice should parallel the use of the original negative in black-and-white motion pictures. Because it is a positive color transparency, it is, however, possible to judge immediately after development the color rendition and other pictorial effects of the scene.
Ansco Color Camera Film is available on both nitrate and acetate base, and designated 735 and 835, respectively.
Ansco Color Camera Film is balanced for exposure by daylight and the best color rendition on exterior exposures will be obtained in bright sunlight. For studio exposures, excellent results are obtained with key-light provided by high-intensity carbon arcs which are modified by Y-1 gelatin filters and fill-light by tungsten lamps for color photography filtered with Macbeth Whiterlite filters. The spectrogram shown in Fig. 3 gives the relative response of the film to the visible region of a daylight spectrum.
Suggested meter settings for the exposure of Ansco Color Type 735 are Weston 8, or G. E. 12.
For optimum print results, it is desirable that the Ansco Color original be slightly underexposed or somewhat heavier in density than is the usual practice when exposing a transparency for screen projection. The reason for preferring a heavy original is to maintain as much of the exposure as possible on the straight-line portion of the H and D curve and avoid inaccurate color reproduction which can result from exposures which fall predominantly in the toe region.
The processing of Ansco Color Type 735 is almost identical to that which has previously been described by Forrest.1 The only variation is a somewhat shorter developing time in both the first and the color developer. In this connection we believe it is indicative of the simplicity of the Ansco Color process that several laboratories have converted existing black-and-white machines for the processing of Ansco Color Film and in all instances very little difficulty has been encountered. At least in one case, the very first roll of Ansco Color Film which was developed on a converted black-and-white machine was of excellent quality.
(1) Direct Prints from Original Color Transparency. – As previously mentioned, the release printing stock for an Ansco Color Type 735 original is Ansco Color Release Film Type 732. This film is also of the reversible type and while fundamentally similar to the other Ansco Color reversible films, it is characterized by a relatively low speed, very fine grain and special sensitization for printing. This printing stock can be developed to a high maximum density to obtain optimum color brilliance. Fig. 4 shows a typical H and D curve for this film. Fig. 5 shows a wedge spectrogram of the Ansco Color Release Film. There are relatively sharp sensitivity peaks in the green and red regions and a partial gap between these peaks. Good separation of the peaks of sensitivity is very essential in a printing film in order to obtain faithful color reproduction.
Ansco Color Release Film will be available on both nitrate and acetate base and designated 732 and 832, respectively.
Most motion picture printers which are suitable for printing present-day black-and-white positive stocks can be readily adapted to print Ansco Color Release stock. If not already available, the following features should be provided on a printer to make it suitable:
(1) A light source which operates at a color temperature of approximately 3000 K.
(2) A means for inserting printing filters into the light path quickly and conveniently.
(3) A condenser lens system for the light source in order to concentrate the light at the aperture. Ansco Color Release Film, with the printing filters in place, will require 2 to 4 times the light needed for printing black-and-white positive fine-grain stock.
(4) It is good practice to provide an air blast or fan as a means of dissipating the heat from the lamp house in order to avoid damage to the filters and film.
Using a regular black-and-white printer with the modifications just described, the printing of the Ansco Color original onto Ansco Color Release Film requires the insertion of filters to balance the color quality of the light source. A standard series of Ansco color compensating filters, in varying densities of yellow, magenta, and cyan, are available for this purpose. Considerable control of the color balance of the release print is possible by the selection of these printing filters.
The processing of Ansco Color Release Film is carried out on the same developing machine and in the same solutions as used for the Ansco Color original. Adjustments of the developing times to suit the particular machine conditions are necessary.
So far we have discussed the camera film and the release printing film for the Ansco Color process without referring to methods for including optical lap dissolves, wipes, and special effects where second generation duplicates of the original Ansco Color will be involved.
(2) Prints from Duplicates. – It is generally recognized that in color reproduction each printing step results in a noticeable degradation in color. For this reason it is desirable to reduce the number of printing operations in color photography to a minimum. However, in motion picture practice it is not feasible in many instances to print from the original color transparency. This is particularly true in those cases where special effects, such as lap dissolves and wipes, have to be incorporated in the sequence of the picture, also for foreign releases where it is essential that a master dupe is available for release printing. Two methods for making master dupes have been worked out for this purpose.
The first method consists of straightforward optical printing of the Ansco Color original onto Ansco Color Type 132 Duplicating Film.
The duplicating stock Type 132 requires about the same exposures as the release stock 732, that is, approximately 2 to 4 times the light needed for regular positive fine-grain stock. The film is processed in the same solutions as the Type 735 original. The developing time in the first and second developer is shorter. A duplicate is obtained which is substantially equal in contrast to the camera original. This first generation duplicate can then be interspliced with the original and used for release printing on Ansco Color Type 732 Release Film. The H and D curve of the Type 132 Duplicating Film is shown in Fig. 6.
The fact that the original as well as the dupe and the release print stock can all be developed in the same machine and in the same solutions represents a very essential simplification of the Ansco Color process. As pointed out before, there are differences in the developing times for these 3 color films, and in order to allow a more exact comparison, the approximate developing times are listed:
The developing times shown are only approximate, since the exact time depends very largely upon the machine speed and the solution agitation in the machine.
There will be an inevitable loss in color brilliance in the second generation duplicate prepared by this method. However, the loss is probably not serious enough to preclude its use for certain lap dissolves, wipes, and other special effects, especially if the subject of these special effects is of such a nature that a very critical judgment of color rendition is not possible. Because of the loss of color brilliance by this method, it is not recommended for making full-length master dupes. For this purpose and where good color reproduction is desired on special effects, the following second method is preferred.
(3) Prints from Masked Duplicates. – In order to counteract the color degradation, the second method of making a master dupe employs a black-and-white silver mask. It is not the purpose of this paper to go into the details of the theoretical requirements of masking, but rather restrict this discussion to the recommendation of a simple procedure for masking Ansco Color Type 735.
A special low-shrink, panchromatic, black-and-white film has been developed for masking in connection with the Ansco Color process. The characteristics of this material are such that the required masking densities are obtained with the least amount of critical control. For this reason, the gamma infinity of the material is adjusted to the masking requirements. In Fig. 7, the characteristic H and D curve of this special masking film is shown. In order to insure good registration, the same printing equipment should be used for the printing of this color correction mask which later on is used for the printing of the masked master dupe. In Fig. 8, a schematic outline of the type of optical printing equipment which can be used for this purpose is shown. The essential features of a suitable printer are 2 synchronized intermittent movements with register pins which are combined with the necessary optical equipment.
In making the black-and-white mask, the original and the mask are run in contact in the camera head while using the projection head empty as a light source only. A yellow filter is placed into the light path while printing the masking film. After the mask has been developed in a regular negative developer, the master dupe is printed. In this operation, the original is run in the projection head and optically registered with the black-and-white silver mask which is now run in the camera head in contact with the Ansco Color Type 132 Duplicating Film.
The printer must be equipped with a viewer or other suitable means so that the registration of the original and the mask can be checked before printing the master dupe. The conformed master dupe can be made in one printing operation, even though special effects may be necessary. In the case where special effects that require mattes are to be inserted, these should be run in the projection head with the original. This method will yield a conformed master dupe that will show little or no loss in color brilliance.
This masked master dupe is then used for printing of the release prints, using Ansco Color Type 732 Release Film in a regular continuous printer with provisions for the insertion of filters and a stronger light source, as described earlier.
So far, only the pictorial part of the process has been discussed, but it is realized that methods of obtaining good sound are of equal importance. Since the release printing stock is a reversible film, a positive black-and-white track is required for printing. The ideal way to obtain the black-and-white positive would be a direct-positive recording. However, equipment to record to a direct positive is not generally available, and the following method has been found almost equally satisfactory and is the one recommended. The recording head of the sound equipment is moved so that the negative recording is obtained on the opposite side of the film. This negative is then printed onto black-and-white positive stock, which will then have the sound track in the proper position for printing directly onto the Ansco Color Type 732 Release Film in the conventional manner.
Dye tracks, especially those obtained by the dye coupling method, have a relatively low absorption in the infrared region. Therefore, the conventional infrared-sensitive photocell, for example type 868, is not too well suited for these dye tracks and a loss in volume amounting to approximately 6 db is encountered. This loss in volume, while serious, still comes within the range where adjustment can be made by fader setting on most 35-mm projection equipment. Fortunately, within the last few years the development of blue-sensitive photocells has progressed and cells are available today which are ideally suited for dye tracks and will play normal silver tracks with approximately the same volume so that interchange of tubes is not required. This photocell, which is at present available from the Radio Corporation of America, is designated as the 1P-37.
Summarizing, the Ansco Color process is capable of producing full color motion picture release prints, including commonly used effects, with only minor changes in equipment which is now used extensively for black-and-white motion pictures. We believe that the Ansco Color process offers a relatively simple method for making motion pictures in color which can be readily mastered by those skilled in black-and-white motion picture techniques.
1 Forrest, J. L.: “The Machine Processing of 16-Mm Ansco Color Film,” J.
Soc. Mot. Pict. Eng., 45, 5 (Nov., 1945), p. 313.
*Presented Oct. 17, 1945, at the Technical Conference in New York.
**Ansco, Binghamton, N. Y.”
(Duerr, H.H.; Harsh, H. C. (1946): Ansco Color for Professional Motion Pictures. In: Journal of the Society of Motion Picture and Television Engineers, 46,5, pp. 357–367.)