International projectionist (Jan-Dec 1947)

Bi-Pack Photography Now A Formidable Color Entry THE method of photography known as "bi-pack" is now in universal use with excellent results, and for the interest and education of the many technicians now interested in this system, the following treatise has been prepared: The records indicate that M. F. de Colombier of France received a French patent on a tri-pack system as early as 1908, but the authority states, "—like so many French patents it is a little indefinite in phraseology." G. Battistini received a British patent in 1915 for either bi-pack or tri-pack. By the tri-pack system two cameras were mounted at right angles to each other. One camera carried two films with their emulsion surfaces in contact; the second camera carried but a single negative. Between the lenses of the cameras was a transparent mirror which transmitted and reflected the photographed image to the respective films. In tbe true sense of the word, this cannot be termed tripack since tri-pack means three films together, i.e., as a pack. By Battistini's two-color systems two films were placed in the camera, their emulsion surfaces in contact, the front film being stained orange to act as a filter to the rear film. The method of projecting the positives from either of the above systems of photography is somewhat nebulous. It is claimed that "positives from each negative were to be stained with the complimentary color FOREST ELECTRONIC LAMP (Continued from preceding page) and has never been used before in any type of lamp. Mr. Bliven suggests that the same result could be obtained by the use of photocells, exciter lamps, etc. Such a setup would necessarily be complicated and quite costly and here again would depend for its operation on an incorrect arc gap before corrective action were taken. This setup would simply be a means for the correction of error instead of preventing error as does the Forest Control. The Forest Electronic Control uses no photocells, exciter lamps, amplifier or apertures. It feeds independently of the arc supply at the exact rate of carbon consumption and maintains the arc at the proper focal point. What could be simpler than this? I believe that when Mr. Bliven has the opportunity to use the Forest Control he will agree that it makes good all the claims made for it. J. K. Elderkin Forest Manufacturing Corp. By WILLIAM T. CRESPINEL of the filter, and the positives might be placed one behind the other in an ordinary projector." Obviously, if this were attempted there could be no register of the images on the screen. It must be assumed, therefore, that like so many other early color experiments, the ideas were quickly abandoned. F. E. Ives patented a bi-pack system in 1919. Like other experimenters, he required that the front film be quite translucent in order to obtain a sharp rear negative. In order to obtain contact of the two films, Ives used a glass plate in the camera aperture and a resilient squeezing pressure at the rear. The glass plate, however, proved to be unusable due to emulsion dust which gathered thereon and, quite naturally, showed as white spots on the negatives. It should be noted that there is no record of any of the aforementioned systems having passed beyond the experimental stage. About 1924, the writer, in conjunction with the late W. D. Kelley, of Prizma fame, conducted experiments with the thought in mind of exploring the further possibilities of bi-pack. A few rolls of translucent film were obtained and, in conjunction with a panchromatic negative, photographed in a Bell & Howell camera. The results were far from encouraging. The rear negative was fuzzy to the point of being unusable, and the exposure between the two negatives very unbalanced as to density due The steady onward march of bipack color photography into the favor of Hollywood technicians was capped by the recent release of the full-length Cinecolor feature film "Gallant Bess". Through the courtesy of our West Coast contemporary, "International Photographer," I.P. readers are afforded a recapitulation of how the bi-pack process developed. to the emulsion differences of the two negatives. Later, in 1928, the writer was confronted with the problem of determining a method of color photography for a new company in which he was interested — namely, Multicolor. A stereoscopic camera was available, the camera naving a pair of matched lenses mounted 2% inches apart. A set of prisms had been constructed to mount in front of the lenses to allow like images to be photographed onto a pair of panchromatic films through complimentary color filters. To the writer, the idea of using a camera of this nature was far from interesting. It was not a practical approach to a color camera, and the idea of a series of prisms and twin lenses presented many optical problems. The idea of bi-pack was once again discussed. It was decided to ignore previous attempts as far as a thin emulsion of the front film was concerned, and to experiment with a front film with standard emulsion. A small roll of standard orthochromatic negative was wound emulsion to emu'sion with a similar length roll of panchromatic negative. No attempt was made to obtain color values. Tbe negatives were placed in a magazine and threaded through one gate of (Continued on page 27) NEW AND ENLARGED HEADQUARTERS OF LaVEZZI MACHINE WORKS Shown here is the new home of the LaVezzi Machine Works, manufacturers of projector replacement parts. The opening of the new factory, now located at 4635 West Lake Street, Chicago, was celebrated with a party which was attended by representative dealers and manufacturers in the industry. INTERNATIONAL PROJECTIONIST January 1947 23