Movies for TV - Early Television Foundation

MOVIE-MAKING EQUIPMENT 89
This defect is found in two forms: random focus drift which
happens for no apparent reason in a release print which is pre-
sumably new, or at least in good condition (of course, when it
occurs in a reel made up of odd trailers or shorts the reason is
obvious) ; and the regular drift already discussed.
It is not caused by buckled film, for this defect is caused by
projection, and focus drift can occur in a brand new reel straight
from the film laboratory. One cause which seems the most logical
and reasonable is film curl. Once it has formed, there is not much
that can be done to correct it in the case of long reels. However,
for short lengths of film the cause provides the solution. Film curl
is caused by film being continuously wound in the same direction
so that it becomes set. Thus even on an apparently straight section
such as one frame, in the gate, there is a very slight radius. A short
length can be cured by rewinding very tightly in the same direction
as originally wound but with the emulsion direction reversed. If
fastened securely and left for a week or so, the curl will be re-
duced.
Incidentally, the safety films are considerably more prone to
this effect than the inflammable film and it is one of the most prev-
alent faults found. Moreover, since 16 mm safety film comprises
most of the film stock used on television, this becomes a point to
which more attention could well be paid by users as well as
processors.
As was mentioned previously "green" or new film, undergoes
considerable change in the first few weeks after it has been proc-
essed. Although it is apparently thoroughly dry when received,
it contains, in reality, a large amount of moisture absorbed during
its passage through the various developing, fixing, and hardening
baths and the numerous washings it receives. The passage through
the processing equipment is also fraught with tension changes, for
speed variations plus differing adjustments of the rollers all act to
apply varying tensions to the film. These affect the film more
easily when it is warm and wet and only slowly are discarded as
it finishes the drying out process.
Film in storage, especially new film, should be rewound