Movies for TV ([1950])

MOVIE-MAKING EQUIPMENT 91 Fig. 3-18. Use of single perforated film introduces complica- tions 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—the emulsion on the outside. The same thing applies 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 opera- tion 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