Three-group zoom lens
US6785057B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 1, 2003 |
| Grant date | Aug 31, 2004 |
| Priority date | — |
| Expiry date | Jul 1, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143507
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A three-group zoom lens includes, in order from the object side, a first lens group of negative refractive power, and second and third lens groups, each of positive refractive power. The first and second lens groups include negative and positive components and the third lens group is a single lens component. All but one lens component may be a single lens element. When zooming from the wide-angle end to the telephoto end, the first and second lens groups move closer together while the second lens group moves farther from the third lens group. The third lens group remains stationary during zooming but moves for focusing. The second lens group includes a diaphragm on its object side. Aspheric lens surfaces are disclosed. The zoom lens satisfies certain conditions for the focal lengths of the zoom lens and a component of the zoom lens, and for Abbe numbers of two lens elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.