Patent ID: 7933082

Claim:
A lens device comprising: a lock mechanism, wherein the lock mechanism includes: a cylindrical operating ring that operates a position of a movable lens which is provided in an optical system for forming an object image or open/closed positions of an openable stop, the cylindrical operating ring being arranged so as to be rotated relative to an inner member provided therein; a hole that is formed in the operating ring so as to pass through an outer circumferential surface and an inner circumferential surface of the operating ring, the hole being elongated in a circumferential direction; a lock knob that includes a shaft portion having a screw portion that is inserted into the hole and is engaged with a screw hole formed in the inner member, and a knob portion that is held by an operator; and a spacer member that includes a convex portion that is rotatably attached to the shaft portion of the lock knob and can be fitted into the hole at a given rotation position, and a base portion having a seating surface that cannot be fitted into the hole and comes into contact with an outer circumferential surface of a peripheral portion of the hole of the operating ring, and wherein, when the lock knob is rotated to fit the shaft portion into the screw hole of the inner member and the seating surface of the base portion of the spacer member is pressed against the outer circumferential surface of the operating ring, the rotation of the operating ring is regulated and the position of the operating ring is fixed.