Wide angle zoom lens
US5526187A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 19, 1994 |
| Grant date | Jun 11, 1996 |
| Priority date | — |
| Expiry date | Dec 19, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/142
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A wide angle zoom lens system. A first lens group has a positive refractive power, while a second lens group has a negative refractive power. The distance between the first lens group and the second lens group is changed during zooming. The first lens group includes a front group having a negative refractive power and a rear group having a positive refractive power. The front group includes a meniscus lens which is concave toward the object and has a negative refractive power, and the rear group includes at least four lenses which have positive or negative refractive powers, wherein 4.5<.vertline.f.sub.F /f.sub.W .vertline.<13; 0.005<.vertline.K/f.sub.F .vertline.<0.07; and 20<.vertline.(f.sub.bW .multidot.f.sub.F)/f.sub.W .vertline.<100 where f.sub.F is the focal length of the front group of the first lens group, f.sub.W is the focal length of the zoom lens at a wide angle position, K is the distance along an optical axis from the surface of the lens closest to the image plane to a rear principal point in the first lens group; and f.sub.bW is the back focus distance at the wide angle position.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.