Super-telephoto zoom lens
US5442486A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 17, 1994 |
| Grant date | Aug 15, 1995 |
| Priority date | — |
| Expiry date | Aug 17, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143105
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An internal focus super-telephoto zoom lens comprises, in succession from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a third lens unit having positive refractive power. During vari-focusing from the wide angle end to the telephoto end, the first lens unit is fixed relative to the image plane and the second lens unit and the third lens unit are moved on the optical axis thereof so as to narrow the air gap therebetween. The first lens unit has, in succession from the object side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power. The lens group having negative refractive power is moved on the optical axis to thereby effect focusing. The super-telephoto zoom lens satisfies various predetermined conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.