Abstract: A lens barrel comprises a lens unit movable in an optical-axis direction of the lens barrel, and a lens holding drum, having a sliding portion protruded in the optical-axis direction at its end portion, for holding the lens unit. The lens barrel also comprises a fixed drum having the same diameter as that of the lens holding drum and provided with a guiding portion at its end portion, for accommodating the sliding portion and rectilinearly guiding the sliding portion in the optical-axis direction, and a driving mechanism for driving the lens unit with action upon the lens holding drum.

Abstract: A lens barrel including a lens holding cylinder holding a lens unit and rotatable about the optical axis of the lens barrel, and a holding cylinder rotating mechanism for rotatively moving the lens holding cylinder to thereby move the lens unit along the optical axis, the holding cylinder rotating mechanism having a rotatable portion disposed outside a fixed cylinder and effecting rotational motion, a rotational motion transmitting portion for transmitting only the rotational motion about the optical axis of the rotational motion of the rotatable portion to the inside of the fixed cylinder, and a holding cylinder rotating portion for transmitting the motion of the rotational motion transmitting portion along the direction of the optical axis and rotating the lens holding cylinder.

Abstract: A zoom lens barrel comprises a holding drum for holding a stop mechanism and a lens unit, a driving mechanism for making the holding drum move back and forth in an optical-axis direction to adjust a focal length of an optical system, and a stop compensating mechanism for compensating an aperture diameter of the stop mechanism by rotating the holding drum about the optical axis, corresponding to the movement of the holding drum in the optical-axis direction. The holding drum has a rotation permitting portion for enabling a portion for holding the lens unit make a rotational motion about the optical axis with respect to a portion for holding the stop mechanism.