| 摘要 |
PROBLEM TO BE SOLVED: To decrease the light quantity in the outer periphery part of a circle of confusion by performing the photometry of a subject and arithmetic operation and opening/closing a diaphragm in the midst of totally opening a shutter based on an exposure value decided according to shutter opening time, the opening/closing speed of the diaphragm and a diaphragm value in a camera equipped with an iris diaphragm and a shutter independently. SOLUTION: The camera is turned toward a subject so as to perform the photometry and arithmetic operation, thereby, the appropriate exposure value is set according to the shutter opening time, the diaphragm opening/closing speed and the diaphragm value. By pressing a shutter button, a diaphragm mechanism provided with a motor for turning a diaphragm blade and capable of controlling the diaphragm opening/closing speed and the diaphragm value acts according to a shutter opening signal informing that the shutter is opened by a synchro contact, for example, and closing the diaphragm at set speed is started. After attaining the set diaphragm value, opening the diaphragm is started. After the lapse of the shutter opening time, the diaphragm is restored to an open state with the closing of the shutter. Thus, the light quantity at the center part of the circle of confusion is made large and the light quantity is made smaller toward the periphery thereof.
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