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.
December, 1930
Motion Picture Projectionist
37
sprocket, the film is liable to jump out of place and ride over the teeth, whereas, if they are set too close they will ride the film, causing creasing, especially on the lower sprocket which acts as a brake on the friction takeup. The small lock nuts on all idler adjusting screws should always be kept tight.
Failure to observe this rule will allow the idlers to drop, not only caus
FIG. 8. The teeth of this
sprocket have been undercut
because the take-up was too tight.
ing creasing but otherwise weakening and permanently marking the film.
It has been found that the safest distance to set an idler from a sprocket is the thickness of two pieces of film. Some manufacturers recommend the thickness of one piece of film but this is insufficient as the distance between the sprocket and idler is too small to allow the average splice free passage.
When the idlers are properly adjusted, it should be possible to move any idler from side to side without danger of touching the sprocket teeth. Badly worn idlers mark the film and should be replaced immediately.
Intermittent Film Guide
The intermittent film guide is for the purpose of holding the film snugly against the intermittent sprocket but otherwise has nothing to do with the
□ □
O O
D Q
FIG. 9. The arrow shows where the teeth have been grooved to a knife-like sharpness by coming in contact with the wall of the film guide. This will ruin film.
steadiness of the picture. Filing the openings in the film guide holders is sometimes necessary to insure the proper amount of side clearance for the sprocket teeth. Moving the film guide from side to side while the projector is running will determine whether or not the teeth have sufficient clearance. Figure 9 shows the results of the wearing of the teeth against the wall of the guide, thereby developing sharp edges which cut into the film.
There is a right and a wrong way to install this film guide in the holder. Figure 10 shows the proper installation— pointed end down. If in the
AUTOMATIC REFLECTOR ARC LAMPS
Silently, Automatically
Producing — Crisp
White Light
FOR SALE BY INDEPENDENT SUPPLY DEALERS
Che Strong Electric Corporation
2501 LaGrange St., Toledo, Ohio
♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦
The HEART of Your Sound Equipment
VISITRON
Type "A" Photoelectric Cells
HIGHER SENSITIVITY — lower fader settings —
BETTER REPRODUCTION
LONGER LIFE — fewer replacements — less servicing
—ECONOMY
LABORATORIES
1803 GRACE ST.
CHICAGO, U. S. A.
♦♦♦♦♦♦^♦♦♦^♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦4