THREE-GROUP OPTICAL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a three-group zoom optical system which has good perfor mance with a smaller number of components by adequately arranging the compo sition of respective lens groups in spite of a small size, high variable power and wide angle of view. SOLUTION: The respective lens groups of the three-group zoom optical system move during variable power from a wide-angle end to a telephone end so as to increase the spacing between the first lens group and the second lens group and to reduce the spacing between the second lens group and the third lens group, in which the first lens group is formed by arranging a negative lens on the extreme object side and forming the second lens group, successively from the object side, of three lenses consisting of a negative lens having an aspheric surface on the aspheric surface, a positive lens and a positive lens. Such three-group zoom optical system satisfies the following condition equations 0.62-L11|<1.4, 1.1-L11 is the focal length of the negative lens arranged on the extreme object side of the first lens group, fw is the focal length of at the wide-angle end and h is the maximum height of the image. COPYRIGHT: (C)2003,JPO