High zoom ratio lens
US6437923B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 2, 2001 |
| Grant date | Aug 20, 2002 |
| Priority date | — |
| Expiry date | Jul 2, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention is directed to a compact and lightweight high magnification zoom lens utilizing a 4-element zoom layout of positive, negative, positive, and positive in refractive property, which is approximately 75 degrees in shooting angle of view at a wide-angle end, approximately F/3 to F/4 in F-number at the wide end, approximately F/5 to F/6 at a tele end, and approximately 6 to 7 in zoom ratio. The zoom lens includes first to fourth elements each comprised of a plurality of lenses, and the elements have respective refractive powers of positive, negative, positive, and positive levels in order from the closest to a subject. Only the second element of lenses is moved for focusing while the conditions described as follows are satisfied:0.065<&phgr;T/|&phgr;2|<0.085  (1)0.35<&phgr;T/|&phgr;1<0.55   (2)0.25<&phgr;T/&phgr;4<0.35  (3)0.75<|&bgr;2T|<0.95  (4)
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.