| 摘要 |
A transport mechanism for the advance of a motion-picture film in a camera is controlled by a photometric circuit to stop the advance of the film for a predetermined number of shutter revolutions, in the event of insufficient lighting, whereby each frame is exposed a number of times depending upon luminous intensity. The photometric circuit includes a photosensor periodically illuminated by a reflective shutter surface; the resulting voltage pulses may be fed to a pulse counter, which reactivates the transport mechanism after a manually or automatically selected number of cycles, or may charge a capacitor to trigger a threshold sensor after a sufficiently long cumulative exposure. A servomotor for the control of an iris diaphragm ahead of the shutter is controlled by the photometric circuit to reduce the incident light, under conditions of nearly sufficient illumination, to prevent overexposure of a frame due to successive exposures at full aperture.
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