| 摘要 |
PROBLEM TO BE SOLVED: To precisely control the exposure of photosensitive film for each exposure by using a shutter being a simple mechanism actuated by a simple driving device. SOLUTION: The received light quantity of light passing through a subdiaphragm is detected by providing apertures 23 and 24 for the subdiaphragm at shutter blades 11 and 12, and driving force at each time is gradually changed so as to increase the received light quantity of an opening process in accordance with a specified function. The operation of the shutter blades 11 and 12 is inverted at a stage where the integrated value of the received light quantity reaches a threshold value, and succeeding shutter speed is set in accordance with the integrated value obtained till completing a shift to a closing process, so that the dispersion of the exposure in accordance with the inversion of the shutter blades 11 and 12 is cancelled in the closing process. In the case that the level of ambient light is high, small reciprocating operation to a maximum aperture by slow shutter speed is automatically selected, and in the case that the level of the ambient light is low, large reciprocating operation to the maximum aperture by fast shutter speed is automatically selected, so that unintentional excess exposure and camera shake are prevented. |
