Patent ID: 8660419

Claim:
A lens barrel comprising: a fixed portion in which an optical system including a focusing lens is placed; an operation member placed so as to be movable to a first position and a second position along an optical axis of the fixed portion and turnable around the optical axis at each of the first position and the second position; a turning member adapted to turn along with the operation member when the operation member moves to the second position, and not to operate along with the operation member when the operation member moves from the second position to the first position; positioning means which positions the operation member at the first position or at the second position with respect to the fixed portion, through a plurality of balls, wherein the positioning means includes a rib portion having a substantially triangular shape in a cross section along the optical axis and an elastic member which presses the balls against the rib portion, when the operation member is located at the first position, the operation member is urged in a first direction to be positioned at the first position by the plurality of balls being placed in abutment with the first sloping portion of the rib portion by the elastic member, and when the operation member is located at the second position, the operation member is urged in a second direction opposite to the first direction to be positioned at the second position by the plurality of balls being placed in abutment with the second sloping portion of the rib portion by the elastic member.