Inverted telephoto type wide angle lens system with a rear focusing unit
US4759619A · kind A · utility
5Cited by
7References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 10, 1985 |
| Grant date | Jul 26, 1988 |
| Priority date | — |
| Expiry date | Dec 10, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/04
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An improvement of an inverted telephoto type wide angle lens system having, from the object to the image side a front lens group of a negative refractive power which is left stationary upon focusing, and a rear lens group of a positive refractive power which is shiftable for the purpose of focusing is disclosed. The improvement is characterized in that the lens system fulfills the following condition: EQU 2.65<.vertline.f.sub.F .vertline./f.sub.R <7.5 wherein f.sub.F represents the focal length of the front lens group, and f.sub.F represents the focal length of the rear lens group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.