Patent ID: 7885016

Claim:
A light quantity adjusting device comprising: first and second diaphragm blades shiftably provided to adjust a size of a diaphragm aperture; a neutral density filter blade provided shiftably in the same direction as the first and second diaphragm blades and having a neutral density filter adapted to cover the diaphragm aperture to reduce a quantity of light passing through the diaphragm aperture; and a drive mechanism adapted to shift the first and second blades and the neutral density filter blade; wherein the drive mechanism is configured to include an actuator, a first cam groove formed in the first diaphragm blade, a second cam groove formed in the second diaphragm blade, a third cam groove formed in the neutral density filter blade, an arm pivoted by the actuator, a first cam-pin provided on the arm so as to project therefrom and engage both the first and third cam grooves, and a second cam-pin provided on the arm so as to project therefrom and engage the second cam groove, and the first, second and third cam grooves are formed such that the arm is pivoted to shift, via the first and second cam-pins, the first and second diaphragm blades oppositely to each other to adjust the size of the diaphragm aperture and such that in a state where the aperture diaphragm is formed at a predetermined size, the neutral density filter blade is shifted between a use position where the neutral density filter covers the diaphragm aperture and a withdrawal position where the neutral density filter is withdrawn from the diaphragm aperture.