COLLAPSIBLE MOUNT TYPE LENS BARREL

摘要

PROBLEM TO BE SOLVED: To eliminate trouble that load for rotating a cam barrel is increased because the tilt angle of a cam groove becomes large in the case of making the diameter of the cam barrel smaller in a collapsible mount type lens barrel using the cam barrel. SOLUTION: Cam grooves 11 and 12 in which the cam pins of a 1st group lens frame and a 2nd group lens frame are fit are provided on the cam barrel 2. Three sets of cam grooves 11 and 12 are formed at the intervals of about 120 deg. respectively in the circumferential direction of the cam barrel 2. Furthermore, by forming the cam grooves 11 and 12 over the range of >= about 120 deg. in the circumferential direction of the cam barrel 2, the tilt anglesβ1 andβ2 of the cam grooves 11 and 12 to a plane perpendicular to an optical axis are made small.