High zoom ratio lens
US6791762B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 1, 2002 |
| Grant date | Sep 14, 2004 |
| Priority date | — |
| Expiry date | Jul 1, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention is dedicated to a compact and lightweight high zoom ratio lens which is configured in 4 lens group zoom system with a deployment of positive, negative, positive, and positive refraction lens groups in order, being approximately 75 degree in shooting angle of view at a wide-angle end, approximately f/3 to 4 at the wide-angle end, and approximately f/6 to 7 at a telephoto end so as to implement an enhanced variable zoom power up to approximately 10. The zoom lens includes first to fourth lens groups each comprised of a plurality of lenses, the lens groups having respective refractive indices of positive, negative, positive, and positive levels in order from the closest to an object. In zooming from a wide-angle end to a telephoto end, the first and second lens groups have a space (air-filled) widened therebetween, the second and third lens groups have a space (air-filled) narrowed therebetween, and the third and fourth lens groups have space (air-filled) narrowed therebetween while the first, third, and fourth lens groups move toward the object, and in focusing, the second lens group alone move, under predetermined conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.