| 摘要 |
PROBLEM TO BE SOLVED: To hold an ND filter arranged in a photographing optical system and provided separately from a diaphragm blade in order to adjust light quantity in a holding frame for turning so that the sudden change of an image may not be caused when the ND filter is put in and out of an optical path. SOLUTION: The ND filter 3 is attached to a mount part 5b provided with a U-shaped aperture opened to the moving direction side of the holding frame 5 at its edge, and surely adjusts the light quantity. Then, the rotary shaft 5a of the holding frame 5 is pivotally supported nearly in the horizontal direction of an optical axis being the aperture part 11 a of a bottom board 11, and the end face 3a of the filter 3 is made a straight line facing toward the rotary shaft 5a. |
