| 摘要 |
PROBLEM TO BE SOLVED: To provide a diaphragm mechanism, by which the optically necessary minimum opening diameter is realized by a usual blade diaphragm mechanism, while suppressing cost with a structure which is made as simple as possible. SOLUTION: In the diaphragm mechanism which possesses a fixed frame 3 for supporting a plurality of diaphragm blades 1a freely rockably and a movable frame 4 fitted freely turnably at the fixed frame 3 and engaged with the plurality of diaphragm blades 1a, and by which the opening diameter formed by the plurality of diaphragm blades 1a is changed by turning the movable frame 4, a regulating member 5 for regulating the turning range of the movable frame 4 is provided at the fixed frame 3 or the movable frame 4, and also the changing range of the opening diameter is made adjustable, by adjusting the position of the regulating member 5 relative to the movable frame 4 or the fixed frame 3.
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