LIGHT QUANTITY CONTROL APPARATUS, IMAGE PICKUP APPARATUS, AND LIGHT QUANTITY CONTROL METHOD

摘要

PROBLEM TO BE SOLVED: To provide a light quantity control apparatus capable of easily controlling the quantity of light incident on an image pick up element, less in the effect of diffraction in aperture stop and small in wavefront aberration even in use of an ND filter; and to provide a control method thereof.

SOLUTION: The light quantity control apparatus includes an aperture stop 26 which has a fixed aperture and which controls a luminous flux of incident light, a light quantity diaphragm 24 which controls the quantity of light transmitted therethrough by varying the size of an opening by the movement of a plurality of aperture blades, and an ND filter 25 which has a transparent area and a light interception area and which is arranged to be movable between a first light interception state in which the transparent area is opposed to the fixed aperture of the aperture stop 26 and a second light interception state in which the light interception area is opposed to the fixed aperture. The movement of the ND filter 25 is carried out when the area of the opening of the light quantity diaphragm 24 is maximum.

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