| 摘要 |
PURPOSE:To extend the number of degree of feedom for selection of the power of each group and to enhance the capacity, by satisfying prescribed conditions in an optical correction type zoom lens where positive-negative-positive lenses or negative-positive-negative lenses are arranged. CONSTITUTION:In the optical correction type zoom lens consisting of positive- negative-positive lenses or negative-positive-negative lenses (a), (b), and (c), the middle lens (b) is fixed, and lenses (a) and (c) before and after the lens (b) are moved linearly in the same direction independently of each other to correct optically the variable power and the movement of the focus plane. Thus, the number of degree of freedom for selection of powers of respective lenses (a), (b), and (c) is increased and the optical correction type zoom lens having the enhanced capacity is obtained. |
