ZOOM ASSEMBLY HAVING IMPROVED CAM BARREL

PROBLEM TO BE SOLVED: To provide a very compact zoom assembly capable of conducting focusing in plural zoom positions, using only one mortor for zoom adjustment and the focusing. SOLUTION: This assembly 100 is provided with a zoom lens 10 having plural lens groups 12, 14, 16 to specify an optical axis, and a cam barrel 140 with its center positioned in the optical axis, and formed with at least one cam groove 175 to move relatively one lens group out of the lens groups 12, 14, 16 with respect to the other lens groups. The cam groove 175 has a set of a main zoom section having slopes inclined with respect to the optical axis in response to zoom positions, ans a set of an intermediate section between the zoom positions. The main zoom section includes sub-sets with the slopes of the same sign, and at least one zoom section with the slope of the sign contrary to them.