| 摘要 |
PURPOSE:To correct aberrational variation of focusing over the entire power variation range by providing the 1st movable lens group which has negative refracting power and the 2nd movable lens group which has positive or negative refracting power to a relay lens group which is fixed on the whole during zooming, allowing both lens groups to meet specific requirements, and moving the both along an optical axis associatively. CONSTITUTION:The focal length of the 1st movable lens group A is denoted as fA and the focal length of the 2nd movable lens group B is denoted as fB; and the quantities of movement of the 1st and the 2nd movable lens groups A and B from positions in infinite-distance focusing on a body at an optional distance with optional focal length are denoted as XA, and XB. Further, the composite focal length of the relay lens group R in focusing on an infinite- distance body is denoted as fR, the composite focal length of the relay lens group R in focusing on a shortest-distance body at the telephoto end is denoted as fR', and the composite focal length of a zoom lens at the wide-angle end is denoted as fW. In this case, inequalities I, II, and III hold. |
