Retrofocus lens system
US5745297A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 11, 1996 |
| Grant date | Apr 28, 1998 |
| Priority date | — |
| Expiry date | Jul 11, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/04
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A retrofocus lens system comprises, in order from a large conjugate side: a first lens group having a negative refracting power and including a plurality of lens elements; a second lens group having a positive refracting power; and a third lens group having a positive refracting power. Each of the lens elements of the first lens group has a negative refracting power. Following conditional expressions (1) to (3) are satisfied: EQU 1.3<D.sub.1 /f<1.8 (1) EQU 0.7 <f.sub.2 /f.sub.3 <1.1 (2) EQU 1.1 <.vertline.f.sub.1 .vertline./f<1.6 (3) where D.sub.1 is air gap between the first lens group and the second lens group, f.sub.1 is a focal length of the first lens group, f.sub.2 is a focal length of the second lens group, f.sub.3 is a focal length of the third lens group, and f is a focal length of whole lens system including the first to third lens groups.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.