Telephoto zoom lens system having four lens groups
US4848883A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 1, 1988 |
| Grant date | Jul 18, 1989 |
| Priority date | — |
| Expiry date | Feb 1, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A four-group type telephoto lens system including a super-telephoto range having a viewing angle (2.omega.) of less than 8.degree. and which includes a focusing lens in a first lens group. The lens system includes for lens groups. The first group is composed of a first sub-part having a positive refractive power, a second sub-group having a negative refractive power, and a third sub-group having a positive refractive power. The second group has a negative refractive power, the third group a positive refractive power, and the fourth group a positive refractive power. Zooming is effected by moving the second group, while focusing is carried out by moving only the third sub-group of the first group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.