International projectionist (Jan-Dec 1954)

than fast lenses and those of short focal length simply because the angles formed by the light rays produce a wider range wherein the smallest circles of confusion do not materially change in size. We may visualize depth of focus as a region between two nearly parallel planes which limit the range of sharp focus. The film, naturally, must lie in this region in order to appear in focus on the screen. If the film flutters outside the limits of this critical region, then it will temporarily go out of focus. The projectionist, when he focuses the picture, moves the entire region of sharp focus into the film! Film Flutter Range The amount of negative buckling, or pincushioning toward the lamp, NEUSCOPE SPLICER MADE SPECIAllY* FOR CINEMASCOPE FILM FOX R K O LOEWS WARNERS EXCLUSIVE FEATURES • Scrape both sides Emulsion from front Four tracks from back • Film locked in original position • Perfect alignment guaranteed * Cinemascope film cannot be spliced on a conventional splicer AS SIMPLE, EASY, AND EFFICIENT AS YOUR STANDARD GRISWOLD AT ALL DEALERS PRODUCTS CORP. ^Ta7»i.»j«-» 1.111 330 West 42nd Street, New York, N. Y. may actually exceed 0.02 inch at high amperages, but at lower arc currents it is normally only 0.005 to 0.01 inch. This is the normal range of flutter in brand-new prints, and it closely corresponds to the depth of focus of lenses in the 6-to-8-inch E.F. class. With well-seasoned prints some of the buckle has been embossed in the film, and the flutter consequently is less than the total amount of bulge as measured from the zero-point of a perfectly flat film-plane. In such a case the flutter-range may be much less than the 0.002-to-0.004-inch depth of focus of lenses in the 4-to-5-inch E.F. class, and accordingly quite invisible on the screen. But with fast, short-focus lenses, as pointed out previously, the depth of focus is so small that even the slightest amount of buckling and flutter will obviate a good screen-image — even if the lens itself be perfect! And we wish to repeat, also, that it is usually necessary to use the most powerful lamps with short-focus lenses for adequate screen illumination, and that these lamps increase buckling and flutter. Projection quality thus finds itself the victim of a vicious circle from which there is little possibility of escape. The lens manufacturers cannot help us, but the film manufacturers can by inventing a more suitable film for high-powered projection. High-Powered Arcs A perfect motion picture screen image is still the dream of projectionists; but cold reality makes us wonder if our dreams will ever come true. It CURTAIN CONTROLS, TRACKS and SPECIAL OPERATING DEVICES VALLEN,lnc. AKRON 4, OHIO seems that every technological innovation of the past few years has deprived the movies of some of the pictorial excellence which all of us took for granted a couple of decades ago. The matter of acetate safety film has been mentioned. The excessively highpowered arclamp is another innovation. Designed at first for the large drive-ins that require them, such lamps are excellent devices for raw lumenproduction. But no one really expects or looks for top-notch picture-quality in a drive-in. It is the increasing use of these lamps in indoor theatres that is objectionable. ii Objectionable or not, however, powerful lamps must be used for illuminating gigantic screens for normal projection and wide screens for CinemaScope presentations. It can THE ORIGINAL Hydro Carbon Cooler Concentrates all the heat at the gas ball. Permits more amparcge. You gsiii 20 to 40% more light from your present lamps. No ccpper coated carbons needed. Pays for itself from the savings on carbons, even with higher ampercj-e. See your Dealer or write to HAL I. HUFF MFG. CO. 659 W. Jefferson BSvd. Los Angeles 7, Calif. EXPORT DIVISION FRAZAR & HANSEN, LTD. 301 Clay Street San Francisco, Calif. Jcntac^msi^^^&^i^o^ CARBONS> Inc. boonton, N. 32 INTERNATIONAL PROJECTIONIST MARCH 1954 I