International projectionist (Jan 1963-June 1965)

Letters... to tl3.e editor Gentlemen: We are subscribers to your magazine for many years and would appreciate your information at this time as to the following: We believe that from long experience in the Theatre Industry, some conclusive figures are available in regard to the proportional screen sizes. We would like to know what recommendable relationship has been determined between the dimensions of screen pictures in standard, panoramic, CinemaScope and 70 mm projections. J. Datshkovsky Cinema Division West rex Co., Mexico There is considerable evidence that non-anamorphic 35-mm projection is becoming standardized at a "widescreen" aspect ratio of 1.75/1. using a projector film aperture measuring 0.825 inch wide by 0.600 inch high. Screen light falls off and image quality deteriorates when higher aspect ratios are used for the projection of regular prints; and the old conventional 3:4-proportioned ratio of 1.333/1 (more exactly 1.375/1) is now considered too nearly square in shape to suit the tastes of moviegoers who are now accustomed to the more panoramic visual sweep of widescreen pictures. Many responsible film producers in Europe and America recommend the 1.75/1 aspect ratio for the most satisfactory widescreen type of presentation with standard 35-mm prints. We heartily endorse this recommendation. Accordingly, we feel that there is no longer any need for such aspect ratios as 1.66/1. 1.85/1, and 2/1, all of which have been used to some extent for showing regular 35-mm prints. Originally 2.55/1, CinemaScope was standardized at an aspect ratio of 2.35/1 by the addition of an optical soundtrack to the four magnetic EQUIVALENT 1.75/1 widescreen lens = 2.35/1 C'Scope lens E.F. 2.35/1 70-mm lens E.F. Conversely: 1.75/1 Widescreen lens = 2.35/1 C'Scope prime lens = 2.35/1 70-mm lens = 1 2.35/1 70-mm lens = 10 soundtracks on CinemaScope prints. The CinemaScope film aperture measures 0.839" x 0.715". and an anamorphic expansion factor of 2X doubles the width of the projected image. The Todd-AO 70-mm projector aperture measures 1.913" x 0.866". giving an aspect ratio of 2.21/1. It is very desirable, however, to reduce the height of the 70-mm aperture to 0.814 inch in order to conform exactly to the CinemaScope aspect ratio of 2.35/1. We therefore regard a 1.913" x 0.814" 70-mm aperture as the most serviceable standard for wide-gauge film. It is good practice to select a set of projection lenses which will give the same height of picture on the screen with all of the various aperture sizes and widths of film. It is a simple matter to calculate the lens focal lengths needed if it has previously been established what focal length is satisfactory for one size of aperture used. If a certain lens E.F. (equivalent focus) gives the right picture height with the old conventional 1.375/1 aperture, multiply this E.F. by the following factors to obtain the correct focal lengths for (a) 1.75/1 non-anamorphic widescreen 35-mm projection, (b) 2.35/1 CinemaScope 35-mm projection, and (c) 2.35/1 70mm projection (see table I . It is not always possible to "match" lens focal lengths exactly, but usually one can come close enough to maintain very nearly the same projected-picture heights with all processes. Of course, whatever picture height is chosen, the screen should be wide enough to accommodate the full 2.35/1 CinemaScope and 70-mm images. That is, the width of the screen should be 2.35 times its height. Some of these aspect-ratio problems were discussed in several articles published in INTERNA FOCUS FACTORS = C'Scope prime lens x 0.6587 = 1.375/1 lens E.F. x 1.1917 = 1.375/1 lens E.F. x 1.3567 = C'Scope prine lens x 0.6587 1.75/1 widescreen lens x 1.5180 75/1 widescreen lens x 1.7282 C'Scope prime lens x 1.1385 TIONAL PROJECTIONIST, e.g. "Non-Anamorphic Aspect Ratios: a Return to Sanity" (Dec. 1961). Of special interest are the two articles under the title "Glamourizing the Screen" in the current September and October issues of IP. Tables of projected picture sizes with various lenses, apertures, and projection distances or "throws" are published by the manufacturers of lenses: where these are not available, the height of the projected picture may be calculated by means of the following formula, the same linear units ( inches or centimeters ) being used throughout: Picture height = Throw x Aperture height Focal length (E.F.) of lens This formula assumes a 0° projection angle. If a steep projection angle prevails, the picture height will be greater than calculated. In such a case use the trigonometricformula on p. 423 of "Mitchell's Manual of Practical Projection." There is considerable leeway allowable in the size and shape of the seating area in a motion-picture auditorium. Above all, the picture should be large enough to be viewed comfortably from even the most distant seats. In general, we recommend that the front row of seats be 2 "picture heights" distant from the screen, and that the back row of seats be no farther away than 6 "picture heights" from the screen — regardless of the width of the picture, which will presumably vary from 1.75 to 2.35 times the picture height. Moreover, the width of the seating area should not exceed 4 times the picture height. As we said, there is no hard-and-fast rule. iP Hornstein Furnishes Nassau Theatre Projection Equipment NASSAU, B. W. I. — The new Shirley Street Theatre has a 40 ft. wide screen, and uses Strong X-16 2500 watt Xenon lamps, Joe Hornstein, Inc., of New York, furnished the equipment and stage drapery treatement. The Shirley Street Theatre is equipped with Century Projection and Cenutry transistorized sound equipment; Bausch & Lomb lenses: Strong rectifiers, and, as noted above. Strong Xenon lamphouses. Engineering and supervision of the installation was by Hal Hornstein and Joe Hornstein, Inc. iP International Projectionist Januarv, 1964