Zoom lens system
US5973854A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 25, 1997 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | Nov 25, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/145129
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens system has first to fifth lens units from the object side. The second lens unit has a negative optical power. The other lens units have each a positive optical power. During zooming, the first, third and fourth lens units move along the optical axis to vary the distances between the lens units. The zoom lens system fulfills the conditions 0.01.ltoreq..vertline.f2/fT.vertline..ltoreq.0.20 and 25.ltoreq.(fT/f34W).times.Z.ltoreq.300, where f2 represents the focal length of the second lens unit, fT represents the focal length of the entire zoom lens system at the longest focal length condition, f34W represents the composite focal length of the third and fourth lens units at the shortest focal length condition, and Z represents the zoom ratio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.