Patent ID: 8743474

Claim:
A lens apparatus comprising: an optical system that includes a movable lens unit; a lens barrel that houses the optical system and includes: a fixed barrel supporting the movable lens unit to be forwardly and backwardly movable along an optical axis of the optical system; and a cam barrel engaged with the movable lens unit, supported by the fixed barrel to be rotatable around the optical axis, and configured to forwardly and backwardly move the movable lens unit in accordance with the rotation of the cam barrel; a weight that is engaged with the cam barrel and forwardly and backwardly moves along the optical axis in a direction opposite to a moving direction of the movable lens unit in accordance with the rotation of the cam barrel, the weight preventing the movement of the movable lens unit when the lens barrel is slanted so that the optical axis is slanted to the horizontal direction, the weight having a circular shape and is fitted outside the fixed barrel to be supported to the fixed barrel, wherein the cam barrel has a first spiral cam groove for moving the movable lens unit along the optical axis and the weight has a second spiral cam groove for moving the weight along the optical axis, and the first spiral cam groove and the second cam groove are different from each other in spiral wrapping direction so that the weight moves along the optical direction in the direction opposite to the moving direction of the movable lens unit.