In a lens barrel of a zoom lens, a luminous flux is divided or its path is switched so that the same luminous flux is directed to both a taking optical system and a finer optical system. Focusing and camera shake compensation are performed before division of the luminous flux or switching of its path so that images observed through a finder are already in focus and compensated for camera shakes. The lens barrel has multiple movable segments to allow the taking optical system and the finder optical system to be moved out simultaneously. To achieve zooming, a holding member for holding both a focusing lens unit and other lens units is moved so that all these lens units are moved simultaneously. Adjustment of the focusing lens unit, necessitated as a result of zooming, is achieved by moving a part of the focusing lens unit within the holding member.