Four-group zoom lens
US6741399B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 18, 2002 |
| Grant date | May 25, 2004 |
| Priority date | — |
| Expiry date | Dec 18, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens is disclosed having four groups of positive, negative, positive, and positive refractive power, respectively, in order from the object side. The second lens group includes, in order from the object side, a biconcave or plano-concave lens, a biconcave lens, and a positive meniscus lens with its convex surface on the object side. The third lens group is a single lens having at least one surface that is aspherical. The fourth lens group includes a biconvex lens positioned between two meniscus lenses, and includes at least one surface that is aspherical. The first and third lens groups are fixed in position, the second lens group moves for zooming, and the fourth lens group moves for both zooming and focusing. A specified condition is satisfied to provide a zoom lens of small overall length, a zoom ratio that exceeds 6, a wide-angle of view, and favorably corrected aberrations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.