International projectionist (Jan-Dec 1952)

SAFETY FILM: PERFORMANCE CHARACTERISTICS (Continued from page 8) that no noticeable flutter existed and no changes in focus except for occasional focus-drift compensation were required, for even the most wavy high-acetyl safety prints. Film Types and Buckling It is a fact well-known to film technologists that high-acetyl safety film buckles much less readily than nitrate film. If we projectionists declare that the high-acetyl film buckles more readily, the scientists who really know about these things will regard our statement with amazement. Buckling is caused by the edges of the film shrinking more than does the middle area. This always occurs when nitrate films are projected by means of powerful arcs which unavoidably make the entire gate very hot while projection is in progress. The film base, itself, is heated to a higher temperature by the hot film runners and tension pads than by direct irradiation in the aperture, which heats the emulsion but leaves the base relatively cool. It is very much as though we ironed the edges of the film with a hot iron without touching the middle. The only way effectively to minimize this permanent deformation of the film is to use "cold" projectors or machines having gates water-cooled in a similar manner. Projectors having only air-cooling of the aperture or heat-filters in the arc beam simply cannot do the job. The very superior resistance of highacetyl safety film to buckling is due primarily to its much greater resistance to heat. Tests have been conducted under EQUIPMENT & SUPPLIES fyr £V£W Theatre Meed! NAT scientifically-controlled conditions which prove conclusively that high-acetyl film base retains its original propreties under heat conditions that cause nitrate film to lose its tensile strength and become so brittle that it shatters. Because the low shrinkage characteristics of high-acetyl base are maintained under conditions that cause the edges of nitrate film to shrink much more rapidly than the middle areas, high-acetyl film is very resistant to buckling. Since using prevue trailers printed on high-acetyl stock, the writer has been spared some of the characteristic troubles associated with reels of film made up by splicing a number of small rolls together. Sound level still frequently varies from roll to roll, but that has nothing to do with the film base. With the exception of a slight change of focus from roll to roll (due, in part, to several changes from black-and-white to color) there has been none of the rapid in-and-out of focus flutter sometimes seen during the first four or five runs of new nitrate ad trailers which had been tightly wound in small rolls immediately after processing. Nitrate film takes a curl and holds it tenaciously. Safety film takes a curl, but loses it when held in the gate of the projector. Film Types and Side-Blurring One projectionist interviewed claimed that safety film resulted in a picture having a blurred area along the righthand side of the screen, while nitrate film permitted a sharp focus all over the screen (Simplex E-7 projectors). Although I did not see a nitrate print projected during my brief visit to that theatre, what the projectionist had said about the blurry right-hand side of the picture was true, and it occurred with both projectors when safety film was run. In cases of this nature the condition of the film-gate runners is usually sus CLAYTON BALL-BEARING EVEN TENSION TAKE-UPS For all projectors and sound equipments All take-ups wind film on 2, 4 and 5 inch hub reels. Silent Chain Drives THE CLAYTON REWINDER For perfect rewinding on 2000-foot reels. CLAYTON PRODUCTS CO. 31-45 Tibbett Avenue New York 63, N. Y. pect. Uneven gate tension may also be involved. In mechanisms employing "studio guides" for edge-guiding prints through the gate the flatness of the filmrunners cannot be checked without first removing the guide strips, an operation too delicate and time-consuming to be done during a show. I kept the matter in mind, hoping that I might sometime encounter the same condition in another theatre. That wish materialized in one of the first theatres on my list. There it was, worse than ever, the blurry right-hand side of the picture which was blamed on safety film. But the fact that only one of my projectors SAVE 22% ON CARBONS! foH|C m«*lC totV>on for Ashcraft "D" and "E", Brenkert-Enarc, Peerless Magnarc and Strong Mogul lamps. Burning average lengths (3V4") down to %" saves 2'/i" or 22.2% of the carbon cost. Uses positive carbon stubs of any length, without preparation. When entirely consumed, the new carbon goes into use without losing the light, or otherwise affecting lamp operation. AVERAGE SAVING $400 A YEAR No more "Will it burn a full reel" guessing. Only $52.50 If your dealer can't supply you, order direct. PAYNE PRODUCTS CO. (Cron-O-Matic Division) 2454 W. Stadium Blvd. Ann Arbor, Mich. ( ) Send literature on the Cron-O-Matic ( ) Ship Cron-O-Matic Carbon Saver: ( ) C. 0. D., including postage. ( ) Remittance herewith. Name Theatre Street City & State . . EXPORT: Frazar & Hansen, Ltd. San Francisco, New York, Los Angeles INTERNATIONAL PROJECTIONIST • October 1952 29