International projectionist (Oct 1931-Sept 1933)

18 INTERNATIONAL PROJECTIONIST November 1931 Specifications for the standard apertures as worked out by the subcommittee in consultation with studio and equipment company technical representatives are shown in the accompanying illustrations (Fig. 1 to 4). Some of the factors and conditions considered are given in the following analysis by J. A. Dubray of the subcommittee: 1. For Negative Films a. The plus and minus camera tolerances which include the location of the aperture (constructional tolerances) ; the size of the aperture (constructional tolerances) ; and the side weave of the film on the register teeth of the intermittent mechanism. b. The plus and minus tolerances which must be allowed in accumulating the camera tolerances with a 54% film shrinkage. 2. For Positive Films c. The plus and minus tolerance required in printing a positive and calculated first from the effect of registering the positive film against the right-hand side of the teeth of the main printer sprocket while the negative registers against the left-hand side; second, from the effect of registering the positive and the negative films in the opposite direction. Both cases for unshrunk positive and accumulating with the tolerances arrived at (b). d. The plus and minus tolerances calculated from the (c) tolerances plus a positive film shrinkage of H%. e. The plus and minus tolerances calculated from the (c) tolerances but with the addition of a positive film shrinkage of 1K%. The results obtained from the above have been derived with the assumption that the negative has only shrunk i/2%. However, since the shrinkage effect constantly progresses , through the printing process as well as while the films are stored away, the calculations have been extended to include a greater negative shrinkage. The following series of computations was carried out, accumulating the plus and minus camera tolerances, with the tolerances necessitated by the various conditions expressed above, with the exception that a maximum 1%% shrinkage of the negative was considered instead of the minimum %%. 3. For Negative Films a'. Camera tolerances same as for (a). t .24-3 a CD o CD CD CD CD SotfWO Tt-XCK. .104 MiM. .ooVMtw. o CD CD O CD a CD CD O ^ .oso'Mna. ^ .lOQ-WHN FIG. 3. SOUND TRACK ■ This drawing is a detail from Figure 1 to show the minimum requirements for sound track width and location b'. Tolerances resulting from accumulation of (a') and VAVo negative shrinkage. 4. For Positive Films c'. Tolerances required in printing with unshrunk positive for both conditions of film registration expressed at (c), but accumulating tolerances calculated at (b') d'. Tolerances calculated through the accumulation of tolerances at (c') and H% shrunk positive film. e'. Tolerances calculated through the accumulation of tolerances (c') and 'A % shrunk positive film. The latest being the extreme case, accumulating a maximum permissible shrinkage and all constructional and register tolerances taken from the camera, the registering tooth, the processing of both positive and negative and those of the printing of the positive film, which are due to the differences in shape and dimensions of the positive and the negative perforations. The above method of determining shrinkage and mechanical tolerances has resulted in the determination of a maximum camera aperture as illustrated in Fig. 1. Taking the above dimensions and computing according to the accumulated tolerances determined at (d), (e), (d') and (e'), the maximum and minimum dimensions of sound track and picture area of positive film are derived as shown in Fig. 4. Advantages to Studio 1. Economies. — Cinematographers estimate that from a half-hour to an hour a day now spent in setting up for composition in three apertures — full frame. Movietone frame, and proportional — can be saved or devoted to improved photography. Scaffold lights can be lowered from three to five feet, thus making possible a reduction in the wattage or number of units. The tops of large sets can be lowered by as much as six feet, and all sets can be reduced in width by nearly ten per cent, without making any change in the placing of essential action and props as photographed for the past year. 2. Improved Quality. — A single aperture will make for better composition on the set for both the cinematographer and the director. The studios will be assured that the picture will be projected as it was photographed. Projectionists have had wide leeway in framing and no guide to show them when their proportional aperture was centered until they saw heads or feet cut off on the screen. Microphones can be lowered from three to five feet, resulting in an obvious advantage in sound quality and convenience for the sound department. Camera lenses can be re-centered on the new aperture for better optical coverage. Advantages in Theatre 1. All pictures can be projected through a single standard aperture, doing away with movable flippers and changes of screen masks, aperture plates and lenses during the show. 2. The frame lines just outside the aperture as they used to be for silent pic I .^lo'C-fclCINKL .&0 vsr .^9?6fe" .lo9 0»ICIW»>. ■I»7»* .IO&6S" FIG. 4. MINIMUM AND MAXIMUM SOUND AjND PICTURE AREAS This drawing is a composite view of the dimensions resultant from the calculation of shrinkage and mechanical tolerances from which Figure 1 was derived