American cinematographer (Mar 1933)

March 1933 • American Cinematographer 9 The Dieterich Process for Composite Photography by William Stull, A.S.C. A NOTEWORTHY contribution to the progress of composite cinematography has recently been made by Dr. L. M. Dieterich, A.S.C., member of the Society’s Research Committee, who has developed the Dieterich Process of Composite Cinematography. According to Dr. Dieterich, this new process combines the major ad- vantages of existing processes, while eliminating their principal disadvantages. It is simple, effective, and practical with existing equipment and materials throughout. As is well known, the existing methods of composite cinematography (disregarding the multiple printing proc- esses making use of the travelling-matte principle) fall into two general classifications: those making use of pan- chromatic color-separation and complementary-color light- ing, and those involving the projection of the background- film on a screen behind the foreground action. The former presents a number of difficulties in the matter of lighting, and often gives rise to “ghosts” and “fringing”, while it also precludes any opportunity of seeing the background in motion as is possible during the making of projection shots. The latter, on the other hand, raises some difficulty in the matter of graininess and even illumination of the field of the background plate. There is also some difficulty in getting a correct balance of focus between the actual foreground action and the projected background, a fault which can seriously jeopardize the desired illusion of reality in the composite picture. In the Dieterich Process, these difficulties are held to be overcome, while the respective advantages of the meth- ods are combined., Essentially, the process is based upon the principle of color-separation, yet it also permits the projection of an auxilliary image behind the foreground ac- tion, if this is desired. Briefly, the process involves the use of three films in the camera: in front, an orthochromatic film with red backing —commercially available under the name “red-ortho” film —as used in normal bipack color-cinematography; with the emulsion to the rear; behind this, a positive print of the desired background scene, preferably printed on Eastman News Stock, and placed with the emulsion to the rear; third, a normal SuperSensitive Panchromatic negative film. These three films are threaded through the camera in con- tact with each other. A standard Mitchell shuttle will accommodate these three films without adjustment; in the Bell and Howell camera the required adjustment to the shuttle is easily made, as is common for commercial bi- pack color cinematography. In either instance, the ground- glass focusing screen must be compensated by the insertion of a .006 in. shim in front of the glass. The background used is a plain white drop, illuminated with red light containing absolutely no blue or green. The foreground action, on the other hand, is illuminated with blue light containing no red. In the tests thus far con- ducted, these colorings have been produced by placing col- ored gelatin screens over ordinary studio incandescent light- ing units. Any trace of blue passing the red filter, backing of the red-ortho or red passing the blue gelatine filter, will result in “ghosts” or other aberrations in the composite film. The same is true of reflected light from either source. In practice, the method of lighting works as follows: the foreground, being illuminated solely by blue light, is photo- Continued on Page 32 Diagram roughly indicating prin- ciple of the Dieterich Process.