EXPOSURE CONTROL MECHANISM FOR IMAGE PICKUP DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent the deterioration of image quality in a middle state leading to the small aperture state from the open state of a diaphragm aperture, and to reduce the occurrence (deterioration) of what is called shading. SOLUTION: In this exposure control mechanism for the image pickup device where the diaphragm aperture is formed by moving diaphragm blades in a direction where they contact with/separate from each other on a plane orthogonal to an optical axis, and an ND filter is not attached to at least one diaphragm blade but an ND filter having at least two-stage transmittance is attached to other diaphragm blade; the moving speed of the diaphragm blade to which the ND filter is attached is made higher than the diaphragm blade to which the ND filter is not attached.