International projectionist (Jan 1963-June 1965)

Record Details:

Something wrong or inaccurate about this page? Let us Know!

Thanks for helping us continually improve the quality of the Lantern search engine for all of our users! We have millions of scanned pages, so user reports are incredibly helpful for us to identify places where we can improve and update the metadata.

Please describe the issue below, and click "Submit" to send your comments to our team! If you'd prefer, you can also send us an email to mhdl@commarts.wisc.edu with your comments.




We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.

Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.

INTERNATIONAL PROJECTIONIST Volume 38 November, 1963 Nymber 1 1 Takeup Action Important To Good Projection By ROBERT A. MITCHELL The lower-magazine film takeup of projectors are only rarely a serious concern to projectionists. It is more or less assumed that, somehow, the film will wind up properly on the takeup reel. This assumption is not always warranted. We have found that incorrect and erratic takeup tension, together with worn holdback sprocket teeth, are frequent causes of print damage. Some of the projectors made during the first decade of motion-picture projection — 1896 to 1906 — had no takeups at all! A large canvas bag was hung underneath the projector stand to catch the film as it issued from the machine. Without the bag, a full 1000 feet of dangerously inflammable nitrate film ran out onto the floor in a loose pile! It is not difficult to imagine the condition of the film after being scratched, trampled upon, and soiled by such rough treatment. Principle of Film Takeup The problem of designing a satisfactory and dependable film takeup was complicated by the variable rate at which the lower reel of a motion-picture machine must FIG. 1 — Conventional type of takeup clutch assembly used in nearly all projectors. The drive pulley, run by a belt from a pulley in the soundhead, is not fastened directly to the takeup spindle, but runs freely on a steel sleeve. In the Simplex, the pulley turns a flange which communicates its rotation to the takeup spindle via a leather slip-disc which allows the reel to revolve more slowly as the film, fed to it from the holdback sprocket, retards its rotation. The tension of the coil-spring which couples the flange and friction disc is adjustable by means of a locknut near the end of the takeup spindle. 4 turn. It is obvious that the rotation of the reel must decrease in speed as the diameter of the film roll increases. This problem was successfully solved in the motionpicture camera by devising a friction-clutch arrangement which allowed the takeup reel to be retarded in its rotation by the film itself. The tension of the clutch was adjusted so that the reel revolved at all times, but without placing undue strain on the film being fed to the reel. The same type of friction-disc clutch was adapted for use on projectors at an early date; but whereas oldtime movie cameras handled only relatively small and light-weight rolls of film (250 to 500 feet), projectors had a film capacity of 1000 feet, soon increased to 2000 feet in order that 2-reel "features" might be shown without an interruption for changing reels. The principal difficulty encountered with projector film takeups was, and still is, the large difference in the diameter and weight of the film roll between the time that the showing of a reel has just begun and the time when nearly all of the film has been wound up at the end of the run. A 200-ft. roll of film wound on a 4-inch diameter core or reel hub. for example, has an outside diameter of 14 in. and a weight of approximately 9 lbs. — plus the weight of the empty reel. The takeup unit must accordingly accommodate a large variation in the weight of reels of film and also be able to wind the film without fail at the end of the run while taking it up without undue strain in the sprocket holes at the beginning when the roll diameter is still small. These difficulties have been aggravated in recent years by the use of 300-ft. 35-mm reels for half-hour TV programs, the increasing popularity of 4000-ft. reels for theatre use (originally introduced for the now defunct double-strip 3-D process), and 4000-ft. reels for 70-mm film ( weighing about 36 lbs. when fully loaded ) . We hesitate to comment on the 13.000-ft. reels of the amazing Philips Solo projector except to express admiration of the engineering ingenuity responsible for the endless parade of cinematic wonders emanating from the Philips factories! Except for special modifications involving separate motors for driving the takeups, the classical frictiondisc clutch still remains standard equipment for transmitting rotary power to the takeup reel. International Projectionist November, 1963