| 摘要 |
PURPOSE:To reduce the size of a zoom lens, by arranging a lens group which has small refracting power and moves associatively with magnification varying operation behind a variable power part, and performing focusing by the movement of part of the lens group. CONSTITUTION:The focusing lens group F having the small refracting power is arranged behind the variable power part consisting of a lens group V for magnification variation and a lens group C for compensation. When the variable power part performs zooming operation from a wide-angle end to a telephoto end, the lens group F is moved in an object-side direction. Then, a lens group having negative refracting power on the image plane side of the lens group F is moved from an infinite distance object to the clsest object in the image-plane direction to perform focusing operation. Consequently, the difference in the extension amount of the lens group for focusing is reduced. Further, the need to increase the overall length of the lens system is eliminated and the size of the zoom lens system is reduced. |
