Compact zoom lens
US5831772A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 4, 1996 |
| Grant date | Nov 3, 1998 |
| Priority date | — |
| Expiry date | Dec 4, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143103
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens is disclosed, comprising, from front to rear, a first, second and third lens units of positive, positive and negative refractive powers, respectively, all the lens units moving forward to effect zooming from the wide-angle end to the telephoto end, the first lens unit including at least one negative and at least one positive lenses, and the second lens unit including a negative lens whose front surface is concave, a positive lens and a cemented lens composed of a negative lens whose rear surface is concave and a bi-convex lens, and the zoom lens satisfying the following condition: EQU 0.2<.beta..sub.2W /.beta..sub.3W <0.5 (where .beta..sub.2W >0, .beta..sub.3W >0) where .beta..sub.2W and .beta..sub.3W are the lateral magnifications in the wide-angle end of the second and third lens units, respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.