A lens barrel includes a stationary member; a rotary input shaft; a manual operating ring rotatably supported by the stationary member and rotated by the rotary input shaft via a gear mechanism; an optical element movable along the optical axis by rotation of the manual operating ring; a hollow-cylindrical...http://www.google.com/patents/US6879445?utm_source=gb-gplus-sharePatent US6879445 - Power/manual lens barrel having a manual operating ring
