Four-group lens
US4319810A · kind A · utility
3Cited by
2References
4Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Dec 18, 1979 |
| Grant date | Mar 16, 1982 |
| Priority date | — |
| Expiry date | Dec 18, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/24
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A four-group lens comprises, in succession from the object side, a first group, a second group, a diaphragm, a third group and a fourth group. These four groups are formed substantially symmetrically with respect to the diaphragm. The air space between the first and second groups and the air space between the third and fourth groups are variable in accordance with a change of the photographing magnification.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.