Zoom lens
US5523888A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 30, 1994 |
| Grant date | Jun 4, 1996 |
| Priority date | — |
| Expiry date | Aug 30, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144507
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens comprising, from front to rear, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of positive refractive power and a fourth lens unit of negative refractive power, zooming being performed by varying each separation between the first to fourth lens units in such a manner that, as compared with the wide-angle end, when in the telephoto end, the separations between the first and second lens units and between the third and fourth lens units are shorter and the separation between the second and third lens units is longer, satisfying the following conditions: EQU D1w-D1t<D2t-D2w where D1w and D1t are the separations for the wide-angle end and the telephoto end between the first and second lens units, respectively, and D2w and D2t are the separations for the wide-angle end and the telephoto end between the second and third lens units, respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.