Movies for TV - Early Television Foundation

88 FUNDAMENTALS
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the heat of the mechanism and cams. Put it in a can after
every use. Don't use reels which have bent flanges. Reels are very
cheap, and it is false economy to put off the purchase. If the edge
binds on film, it can prevent unwinding and cause the drive
sprocket to strip the perforations; if it is on the take-up sprocket,
it may cause film to spill into the magazine and tangle with the
take-up drive.
Sprocket teeth must be properly engaged before closing any
pressure pads; otherwise it is possible to cause holes in the picture
or the sound track. Improper threading can also cause the loss of
upper or bottom loops the bane of every projectionist.
Films must be kept at an even temperature and away from
excessive heat. It is best to keep a moist pad in the can to maintain
a slight amount of dampness in the film if it has to be stored in a
very hot, dry place.
New film, or "green" film as it is sometimes called, is always
a bother to project. Although it may feel dry, it is actually not
so and is still in the process of returning to its previous size. In a
reel of 100 feet, there may be as much as one foot stretch. It may
not seem much only 1 per cent but 1 per cent can make a lot
of difference between a smooth, well-fitting film passage
sticking gate.
and a
Focus Troubles Focus drift is a phenomenon which occurs
during projection and evidences itself by a gradual change of focus
throughout the showing of the film. It can cause headaches for
the shading technician as well as the master control engineer, for
it leads them to attempt electronic focus adjustments in the be-
lief that drift in the electronic equipment has occurred. It often
happens that a film is in perfect
focus at the commencement of
projection, but if it is not watched very carefully it may slowly
change. The error is not usually sufficient to be extremely annoy-
ing, unless it becomes very bad, but it will produce eyestrain for
the audience. It is probably more noticeable in theatre projection
than in television since most television screens are not too sharply
focussed anyway.