Movies for TV - Early Television Foundation

MOVIE-MAKING EQUIPMENT 91
Fig. 3-18. Use of single perforated film introduces complications
when different systems are used such as reversal, or posi-
tive/negative printing. In order to have sound and picture
emulsions on the same side when printing A- and B-winds are
required. An "A" wind has perforations towards the observer
with the film coming off the top, and round reel hole towards
the observer. "B" wind has the perforations away from the
observer under the same conditions. Emulsion is in in each
case. (Based on a proposed American Standard.)
impregnated with camphor by dissolving a block in some quick
vaporizing liquid such as amyl acetate, acetone, or alcohol. If
poured on the pad, the liquid will evaporate, depositing camphor.
A water and glycerine solution in the proportions of about twenty
to one is then sprinkled on the pad to moisten it.
Safety film may be treated in the same way except that only
the water and glycerine solution is needed. If one treatment does
not cure it, it may be repeated.
One would think that a simple little thing like winding a film
could not be complicated but it is. Of course, for 35 mm film
there is only one way
thing applies
the emulsion on the outside. The same
to 16 mm silent film. But when 16 mm sound film
is considered, it is found that there are two methods of winding it
the A-wind and the B-wind. These are illustrated in Figure
3-18. These two methods exist due to the various modes of operation
of current equipment. Due to the use of reversal film, care
must be used when recording by the double system to ensure that
the type of film-winding used matches the position of the emul-
sion of the picture film. Some idea of the complications which
arise may be obtained from this : if a negative picture is made the