Variable focal length objective system has movable and fixed sub-groups that maintain first and second mutual separations in first and second variation regions

摘要

The system has several lens groups (10,20) that can be moved relative to each other to vary the focal length. At least one group is a changeable lens group with two or more lens sub-groups (S1,S2), of which one is movable along the optical axis with respect to the other. The first sub-group and the other sub-group maintain a first mutual separation in a first variation region and maintain a second separation in a second variation region that contains the first variation region and a different variation region.