Projection engineering (Jan 1932-Mar 1933)

MAY, 1932 Page 21 of the two mirrors and the placement of the viewing screen, makes it possible to obtain a total deflection of 0.75 inch on the screen with considerably less power than is normally required by the oildamped type of recorder galvanometer to produce 100 per cent modulation. Advantages The Type PB-30 remote level indicator makes practicable remote monitoring and mixing. Its use eliminates the necessity for the placement of the recorders on the set, and they may be grouped and located in any convenient space available in the studio. This brings the amount of equipment required on the stage to the minimum of a mixing panel, a remote level indicator and a sound monitor. The remote level indicator may be mounted on the top of the mixer panel or in any other convenient location for observation. With a mixer panel, a remote level indicator, and a monitor loudspeaker only on the stage, a very much smaller booth may be used with a resulting increase in mobility and ease of placement. If headphone monitoring is used in place of the monitor loudspeaker, the booth may be dispensed with entirely, the space on the set occupied by the operator and equipment is reduced to a minimum, and the facilities for operating under adverse conditions are greatly increased. Other volume indicating devices hitherto used will not serve the same purpose since they indicate average values, rather than the instantaneous peak values of volume as does the Type PB-30 amplifier. If other devices are used considerable over-shooting on the film may result, which will not be indicated by the meter. On the other hand, the exact and instantaneous duplication by the remote level indicator CONDENSING LENS GALVANOMETER Fig. 2. Line diagram illustrating principle of operation and electrical connections of the Type PB-30 remote level indicator. QGALVQ LINE COUPLING /TRANSFORMERS-^ P 'RECORDER GALVANOMETER t " TO LINE of the action of the recording galvanometer provides an accurate indication of the volume of recorded sound at all times. (a) The recorder lamp should be adjusted vertically and laterally until the light beam falls centrally upon the mirror of the galvanometer. The lamp may be adjusted vertically by loosening the clamping screws holding it in the socket. The lamp may be adjusted horizontally by loosening the two screws holding the socket to the base casting, which will permit the socket to be pivoted about the screw nearer the condensing lens support. (b) The adjustment for zero modulation is made by means of the mirror adjustment screw. With no sound current input to the galvanometer the adjustable mirror should be set so that the left N0TE> WITH TYPE ?k-l AMPLIFIER RACKS AND TYPE PR-I RECORDERS THE SEN5ITIVITY CONTROL WILL 3E CONNECTED IN PARALLEL WITH THE GALVANOMETER II J LOCAL BATTERY hand margin of the aperture image will coincide with the center line on the viewing screen. (c) The adjustment for full modulation is made by means of the sensitivity control (the variable resistor). With a sound current input at 1,000 cycles, regulate the volume at the amplifier to produce full modulation of the recorder light beam. The aperture image on the viewing screen will appear to expand. Now adjust the sensitivity control on the remote level indicator until the lefthand margin of the aperture's vibrating image coincides with the left-hand margin line on the viewing screen. When the above adjustments have been made, the remote level indicator will simultaneously duplicate the performance of the recording galvanometer. AAA Unif orm image rrame h GENERAL adoption by theatres throughout the United States and Canada during April and May of the new uniform image frame size for' motion picture projection machines, established by the Academy of Motion Picture Arts and Sciences, will mark one of the final steps in the technical transition from the silent motion picture to the talking film. Improvements in the photographic appearance of the picture on the screen will result from the recommendations, made by the motion picture production industry's cooperative organization after two years of surveys and researches. Hollywood studios benefit by a similar Academy uniform image frame size in use since February 15, which permits speedier cinematography and more flexible technique in talking picture making. Theatre managers and projectionists will receive through their exchanges detailed instruction leaflets covering the changeover to the new system. The leaflets will accompany the new picture releases, many of which already have been photographed through the new Academy uniform camera aperture. Uniformity in the size and shape of pictures as photographed in Hollywood and projected in theatres is attained by adoption of a uniform size for camera apertures and one for projectors. The aperture is the camera's "eye," its size and shape limiting the area on the motion picture film, which will be affected by light rays during the photographing of a motion picture. Similarly the aperture in the projection ma chine limits the size and shape of the area of the film, which is to be projected in greatly magnified form upon the theatre screen. The adoption of a uniform image frame size will result in a closer coordination between the cameras of Hollywood and the projection equipment of the theatres, eliminating at one stroke expensive and troublesome variances in photographic and projection practices, which followed upon the coming of the sound device to motion pictures. Production and theatre companies adopting the Academy uniform image size, are : Columbia, Darmour, Educational, Fox, Hal Roach, Metro-Goldwyn-Mayer, Paramount-Publix, RKORadio, Mack Sennett, Tiffany. United Artists, Universal and Warner Bros.First National.