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1954-55 Theatre Catalog, 12th Edition, Page 258 (222)

1954-55 Theatre Catalog, 12th Edition
1954-55 Theatre Catalog
1954-55 Theatre Catalog, 12th Edition, Page 258
Page 258

1954-55 Theatre Catalog, 12th Edition, Page 258

taken of this opportunity to introduce magnetic type sound recordings by which means it is possible to provide in the theatre better technical performance than can be had with the present optical systems.


Because of the change in the film standards, the amount of space used by the image, the kind of image and stereophonic sound, certain additions to and modification of the booth equipment must be made. These are as follows:

Projection Sprockets

The sprocket hole sizes on the film and their relative spacing have been changed. The film dimensions are shown in Figure 1. This requires that all of the sprockets and perhaps some of the keepers and pad rollers must be changed. By inspection of Figure 2 it will be seen that the designs have been produced in such a manner that the new sprockets will handle all existing and past product except, possibly, badly shrunk nitrate film. It is obvious that with the new sprockets it [is not necessary that the projectionrist change these to project any other product which presently exists, but it is imperative that CinemaScope product is 'not run until such sprocket change has been effected.

In view of the better technical art available today, all of the tolerances for shrinkage and manufacture have been minimized and it is important that the intermittent sprocket be accurately lined up with the edge guiding element in the projector so that the sprocket tooth nearest the guided edge will engage the perforation in the center of the hole. The adjustment of pad and keeper roller clearances should be carefully made according to manufacturers specifications.

All new parts, as well as all parts of the reproducers, should preferably be demagnetized after rather than before installation to eliminate residual fields which result from manufacture or handling, Whenever mechanical work is done on the magnetic reproducing head, these parts should be demagnetized.

As at present, a take-up adjustment that is too tight will cause nicking on the back edge of the perforation, and, therefore, this should be watched. Large hub reels and slow starting motors minimize this possibility.


The size and placement of the CinemaScope image on the film is different from the present standard size and position and hence a new aperture plate is required (See Figure 3.). The standard size of this aperture plate is 0.912 by 0.715 inches and a plate with an opening of these dimensions may be used if the projection angle is low so that the small amount of picture keystoning that occurs might be taken care of by the screen masking. In the case of steep projection angles, it will be necessary to obtain an aperture plate with somewhat smaller dimensions of the opening to permit shaping of the aperture to correct the larger amounts of picture keystone. The method of correcting for horizontal and vertical keystone is the same as now practiced whereby the top

edge of the aperture is made shorter than the bottom and the sides sloped to meet the lower edge. In addition it may be found desirable also to correct for the projector offset from the screen center line, and in this case, one side or the other will be longer. With a curved screen as used f0r CinemaScope, the bottom, and often the top, of the screen picture will be curved. Should this curvature be considerable it is also desirable to shape the aperture top and bottom to obtain picture edges parallel to the masking. Exaggerated drawings of typical plates are shown in Figure 4. Because of the large magnification in the horizontal direction filing of the plate for correction must be very carefully done. For example, a picture 50 feet wide is about 600 times the film image size, therefore, ten thousandths of an inch in the horizontal direction on the plate would make a six-inch change in picture.

Also, in some cases,.due to the larger aperture, there may be obstructions to the light path in the projector. These will be observed as loss of light or fuzzy edged shadows around the picture periphery. In some projectors the ob plied by all manufacturers will be installed between the upper magazine and the top of the projector casting. Because of this arrangement, the picture precedes the sound on the composite film and a standard displacement of 28 frames has been adopted. Therefore, adaptor plates must be used on the film path length, between the picture aperture and sound pickup head, adjusted to meet this offset on the various models of projectors. It may also be necessary to change the upper magazine type or use an adaptor plate to fit the magazine to sound head. The specific equipment situation should be investigated at the time of ordering sound heads and other parts to avoid later delays and troubles. In some cases, as with old or orphaned equipment, the installation may require some mechanical work on the projector to permit the installation of the sound head.


It is presumed that the respective equipment manufacturers will furnish parts or instructions to the theatre installer or service man to take care of peculiarities in their designs which


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FIGURE 3 SHOWS that the sin and placement of the CinemaScopo image on the film in different from the present sin and position, and hence a new cpcrluto plate is required for proper projection.

struction can be the light baffles or the light beam openings in the castings or housings. Correction may require minor mechanical work to clear these openings.

With the CinemaScope attachment on a long focal length lens it may be found necessary to extend the front shutter and/or shutter guard on some projector models; or, if it is more convenient, a single rear shutter could be usad as has been done in the past.

Sound Heads

The magnetic sound heads to be sup might damage the magnetic sound tracks, result in excessive wear or cause abrasions or other marks in the picture area.

Film Handling Equipment

Film splicers ordinarily are equipped with register pins and these must be changed or new equipment obtained to handle CinemaScope film. The exhibitor may undertake to make the small mechanical change himself, using the facilities of some local shop or by returning the apparatus to the manufacturer, or

1954-55 Theatre Catalog, 12th Edition, Page 258