Patent ID: 7473042

Claim:
A light-amount adjusting apparatus comprising: two aperture diaphragms that move in such a direction that the two aperture diaphragms come close or get away with respect to an optical axis of an incident light to adjust a size of an aperture opening; and a holding unit that holds the aperture diaphragms, wherein at least one of the two aperture diaphragms includes an optical filter having a predetermined light transmittance characteristic, wherein the optical filter freely advances and retreats in a direction of the aperture opening in conjunction with a movement of the aperture diaphragm which has the optical filter, wherein the holding unit includes rotating shafts that guide the aperture diaphragms, wherein each aperture diaphragm includes guide holes that are engaged with the rotating shafts, and wherein the optical filter includes a rotation center hole that is engaged with one of the rotating shafts so that the optical filter rotates about the one of the rotating shafts.