Patent ID: 8602664

Claim:
A lens barrel comprising: diaphragm blades each having a cam engagement part; a holding member that holds the diaphragm blades so as to be rotatable in directions to open and close an aperture; an energizing member that energizes the diaphragm blades in a direction to close the aperture; a moving member that has cam surfaces that engage the cam engagement parts of the diaphragm blades, and that moves in an optical axis direction so as to rotate the diaphragm blades in a direction to open the diaphragm blades by cam actions between the cam engagement parts and the cam surfaces against energizing force of the energizing member; and regulation parts that regulate the operation of the diaphragm blades in the direction to close the aperture by the energizing force of the energizing member so that at a position where the aperture becomes a minimum, the cam surfaces do not engage the cam engagement parts.