| 摘要 |
A photographic apparatus having a structure for automatically determining the exposure aperture according to the lighting conditions. An electrical circuit is provided with a switch for opening and closing the circuit. A photosensitive resistor is connected with the circuit for influencing the current flowing therethrough according to the intensity of the light which is received by the photosensitive resistor. An adjustable diaphragm is provided to determine the size of the exposure aperture, and this diaphragm has a fully closed position where no aperture is provided. A moving coil instrument is operatively connected with the circuit and with the diaphragm for automatically adjusting the latter according to the intensity of the light which is received by the photosensitive resistor. When the switch opens the circuit, the moving coil instrument automatically places the diaphragm in its fully closed position, so that when the structure is not used, with the circuit open, no light will pass through an objective with which the diaphragm coacts.
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