288 THREE-DIMENSIONAL PHOTOGRAPHYspeeded up to the same speed. The camera is equipped with a
stereo reflector and a half-speed oscillating selector shutter which
impresses the rights and lefts alternately upon the film. The pro-
jector has a similar oscillating shutter with Polaroid films set at
right angles in the two halves, thus the right and left images are
projected in succession at double speed. When viewed with the
polarizing spectacles, the stereo relief is experienced.
- The projector and each spectator is supplied with a flicker
shutter which mechanically obscures the two stereo images alter-
nately. The shutter may be rotary, rocking, or sliding, and may
be actuated by rotary motors, magnetic motors, or solenoids. A
shutter geared to the fan motor of the projector and actuating the
individual viewers through solenoid control, is simple and eff ec-
tive.