Inverted-telephoto type wide angle lens system
US4806003A · kind A · utility
9Cited by
3References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 28, 1987 |
| Grant date | Feb 21, 1989 |
| Priority date | — |
| Expiry date | Aug 28, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/06
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An inverted-telephoto type wide angle lens system is provided which comprises from the object side to the image side: a first lens group of a negative refractive power; a second lens group of a positive refractive power; an aperture diaphragm; and a third lens group of a positive refractive power; wherein the second and third lens groups are shiftable to the object side along the optical axis of the lens system at different speeds from one another in a focusing operation to a closer object while the first lens group is stationary on the optical axis in the focusing operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.