Lens barrel, photographic apparatus, and optical apparatus

摘要

A lens barrel has its collapsed length which can be further decreased and its extended length which can be further increased. A photographic apparatus incorporates the lens barrel into its body. A lens barrel is equipped with a first gear which is rotatably supported by a straight-ahead key ring and rotates being driven by rotation of a middle tube and a second gear which receives driving force from the first gear and retracts a second lens group to a predetermined retracted position off the optical axis of a zoom lens during collapse and advances the second lens group onto the optical axis during extension. The second gear lacks teeth in that part which faces the first gear when the second lens group is at the retracted position during collapse. Consequently, the first gear runs idle while facing that part thereby holding the second lens group at the retracted position.