| 摘要 |
<P>PROBLEM TO BE SOLVED: To realize a zoom lens of an inner focus system having small size and high performance, a small travel of a focus group, a half field angle of 41 degrees or more at a wide angle end, a variable power ratio from 2.8 times to 3.5 times, and resolution corresponding to an image sensor having pixels exceeding 5 million-10 million. <P>SOLUTION: A zoom lens is arranged with: a first positive lens group I, a second negative lens group II, a third negative lens group III, a fourth positive lens group IV and a fifth positive lens group V in an order from an object side in an optical axis, and an aperture diaphragm S between the third and the fourth lens group. When varying power from the wide angle end to the telephoto end, all lens groups are moved so as to increase an interval between the first and the second lens group and an interval between the second and the third lens group, and decrease an interval between the third and the fourth lens group and an interval between the fourth and the fifth lens group. The third lens group is constituted of one negative meniscus lens with a concave surface facing the object side, and focusing is performed by moving the third lens group in the optical axis direction thereof to satisfy conditions (1)-(3). <P>COPYRIGHT: (C)2013,JPO&INPIT |
