International projectionist (Jan-Dec 1954)

group includes probably the worst offender from the standpoint of shutdowns, that is film. By far the majority of shutdowns are caused through film breaks. Film breaks should never happen. This is one aspect of the projectionist's job where he cannot have the faintest excuse for a dark screen. The film may come from the exchange ready to fall apart at a sneeze but that is still no excuse. It is the projectionist's job to check it and make sure it is in running shape before it is ever placed around a sprocket. If this involves an unreasonable amount of time and work, throw the film back at the exchange and demand better prints. Scream to high heaven about your bad prints and pretty soon they will make sure you get them in pretty fair condition. This writer on a number of occasions has refused to run prints considered to be in dangerous condition. The exchange had good prints in the theatre before show time. After this happens a few times it is surprising how few poor prints you receive. Believe it or not, on several prints with unavoidable defects, the exchange has written to let me know about it several days in advance. You don't have to be close to the exchange to establish this policy. Our film is shipped 120 miles to us. The answer to the whole problem is preventative maintenance — not repair. Get the trouble before it starts. Equipment, regularly and systematically inspected will give good service and few breakdowns. WENZEL PROJECTOR CO. LENS MOUNTS Anamorphic and A" Type Wenzel Pro 50 and Pro 4, Regular Rear Shutter Simplex, Super Simplex and E-7 type Projectors, Ballantyne "B" & "BW", cnn be easily converted to use the 4" Projection Lens. ALSO AVAILABLE: Anamorphic Lens Supports, Large or Small, for all above mentioned Projectors and Century C <S CC models. Send for Illustrated Brochure. 2505-19 S. State St., Chicago 16, Hi. w\ ONE Projection ■^ Lens For ALL ly Aspect Ratios PACIFIC OPTICAU CORPORATION 5965 West 98th Street Los Angeles 45, Calijornia The original variablefocus lens-attachment. Projects non-anamorphic prints to full screen height regardless of aspect ratio. Provides perfect matching for dual strip 3-D projection. Saves the price of numerous lenses of different focal length. Write for free illustrated literature and name of nearest distributor. LETTERS TO THE EDITOR (Continued from page 13) 78 amps., but you will have to stop cooling off your carbons! Details of Strong Test The Strong Super "135" projects to the screen 16,000 lumens with the shutter running and anamorphic lens on. Since the 50 x 19% foot screen used in the test has an area of 975 square feet, the mean intensity of illumination at the screen has a value of 16.4 foot-candles. As side-to-center light-distribution is ordinarily a matter of 65%, illumination at the center of the screen is 19.9 foot-candles. Now, most matte white screens have an average reflectance of about 76% when perforated. The brightness of the center of this screen, illuminated by the Strong lamp with projector shutter running, is accordingly 15.2 footlamberts. That's just what we claimed. Your lamp setup gives very nearly 8,500 lumens at 78 amps when the shutter is running and when the anamorphic lens is used. Rest assured that this is a generous estimate. 8,500 lumens is just about the best you can expect to do with watercooled, non-coated carbons in a simplified H. I. lamp at 78 amps. You are burning current merely to heat water ! ! You could be getting 10,000 lumens without those water-jackets! Screen Light Inadequate Your 45 x 24^2 foot screen has an area of 1,1021/2 square feet. With 8,500 lumens covering this surface, the mean intensity of illumination is 7.7 foot-candles. With side-to-center distribution of 65%, illumination at the center of your screen is 9.3 footcandles — damned little, if you ask us. Since an aluminum screen has a reflective value of about 240% opposite the incident optical angle, the brightness at the center is 22.3 footlamberts. At this point you will undoubtedly protest that your center brightness was found to be 45 foot-lamberts by actual For DRIVE-INS&THEATRES with HUGE, WIDEAREA SCREENS • CARBONS, Inc. BOONTON, N.J. 30 INTERNATIONAL PROJECTIONIST • AUGUST 1954