| 摘要 |
<P>PROBLEM TO BE SOLVED: To realize a compact, high-performance zoom lens having an unprecedented wide angle and large diameter. <P>SOLUTION: A zoom lens is configured as follows: a positive first lens group I, a negative second lens group II, a positive third lens group III, and a positive fourth lens group IV are arranged in order from an object side to an image side, and a diaphragm S is arranged between the second lens group and the third lens group; each lens of the first or the fourth lens group moves in varying magnification from a short focus end to a long focus end in such a way that an interval between the first and the second lens groups increases, an interval between the second and the third lens groups decreases, and an interval between the third and the fourth lens groups increases; the third lens group III is composed of a positive lens, a first cemented lens obtained by cementing a positive lens having a projected surface on the object side and a negative lens having a recessed surface on the image side, and a second cemented lens obtained by cementing a positive lens having a projected surface on the image side and a negative lens having a projected surface on the image side, in order from the object side to the image side; the focal distance f3 of the third lens group and the focal distance ft of the entire system at the long focus end satisfy a condition (1). <P>COPYRIGHT: (C)2013,JPO&INPIT |
