Zoom lens and zooming method
US5574599A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 16, 1993 |
| Grant date | Nov 12, 1996 |
| Priority date | — |
| Expiry date | Nov 16, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143503
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens comprising, from front to rear, a first lens unit of negative refractive power, a second lens unit of positive refractive power and a third lens unit of negative refractive power, wherein during zooming from the wide-angle end to the telephoto end, at least the second lens unit and the third lens unit move axially forward, and the following conditions are satisfied: ##EQU1## where f.sub.W and f.sub.T are the shortest and longest focal lengths of the entire system, respectively, f.sub.1 is the focal length of the first lens unit, f.sub.2 is the focal length of the second lens unit, and f.sub.3 is the focal length of the third lens unit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.