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.