How to add sound to amateur films (1954)

double-perforated stock, you can use reversal film in any camera. Moreover, you can have your silent films striped and add sound to them without making expensive duplicates. Unfortunately, there is a danger of sprocket modulation with shrunken films. This is due to the variable curl in the film next to the perforations. As each perforation goes by, the stripe moves in and out of contact with the record/ playback head. Consequently the sound is modulated by an unpleasant throbbing. This trouble is considerably reduced when a spring-loaded roller presses the film firmly on to the record/playback head. HalfTrack Half-track is another way of striping a 16-mm. film. It consists of a 50-mil (0-05 inch) stripe applied to a singleperforated optical sound film. The stripe covers half the width of the optical track, leaving the other half free to be scanned in the usual way. Thus you can always choose between playing the optical track or sound recorded on the magnetic stripe. For professional purposes this is frequently useful. For the amateur, the system has limited appeal. However, it does mean that without renouncing your ability to use the original track on a film you have bought, you can provide sound better suited to your personal requirements. Sound recorded magnetically in this way is good. It is, in fact, better than sound from a striped double-perforated film. On the other hand sound from the optical track suffers to some extent, even if the type of optical recording lends itself to the process. Variable density recordings can be half-striped successfully. Variable area recordings can be half-striped provided they are symmetrical about the centre of the track. They will, however, suffer an increase in noise and distortion. Unsymmetrical or unilateral variable area recordings are not suitable for half-striping at all. Before having a film half-striped, make sure the type of optical track is the same throughout. Title music, for 104