Abstract: There is provided an optical device which comprises a fixed barrel, a movable cam ring, and collars and abutments. The movable cam ring is shifted relative to the fixed barrel to move an optical unit, the movable cam ring being fitted to the fixed barrel. Collars and abutments can be engaged with each other when the movable cam ring is in a predetermined positional relationship with respect to the fixed barrel. The collars and abutments preventing the movable cam ring from being disengaged from the fixed barrel and displaced in a direction along an optical axis relative to the fixed barrel.

Abstract: An apparatus, such as an image pickup apparatus, includes an optical unit a moving direction of which changes from one of a drawing-out direction and a drawing-in direction to the other of the drawing-out direction and the drawing-in direction in process of varying a focal length from one of a shortest focal length end and a longest focal length end to the other of the shortest focal length end and the longest focal length end, the optical unit having possibility of receiving an external force in the drawing-in direction, a driving device which drives the optical unit, and a control device which controls the driving device.