Abstract: A lens-driving cam mechanism includes a zoom cylinder rotatable about the optical axis of the lens and a zoom cam ring incapable of rotation about the optical axis provided on the peripheral surface of the zoom cylinder. A front cam portion and a rear cam portion are formed on the zoom cylinder. Cam followers which contact with the front cam portion and the rear cam portion are formed on the peripheral surface of the zoom cylinder. When the zoom cylinder rotates, the zoom cam ring is moved along the optical axis by the cooperation of the cam portions and the cam followers. The zoom cam ring has on the inner surface thereof a cam follower-inserting groove for permitting one of the cam followers to pass therethrough so that the zoom cylinder and the zoom cam ring can be assembled.

Abstract: A holding mechanism for holding an optical element comprises a holding frame and a retaining member. The holding frame includes first and second positioning portions. The optical element is positioned in one direction along parallel to the optical axis by the first positioning portion and is positioned in a direction perpendicular to the optical axis by the second positioning portion. After inserting the optical element and the retaining member into the holding frame, supersonic vibration is applied to generate heat and produce a high temperature at a contact portion of the holding frame and the retaining member, so that the contact portion welds due to the high temperature for establishing another positioning portion positioning the optical element in an opposite direction along to the optical axis. The retaining member is molded from a thermoplastic resin, and the holding frame can be made of a metal material as well as of a thermoplastic resin.