High-aperture-ratio inner-focus telephoto lens
US5490014A · kind A · utility
19Cited by
3References
13Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Dec 16, 1993 |
| Grant date | Feb 6, 1996 |
| Priority date | — |
| Expiry date | Dec 16, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143105
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A high-aperture-ratio inner-focus telephoto lens comprises a first lens group of positive refracting power, a second lens group of negative refracting power and a third lens group of positive refracting power arranged in the named order from the object side, in which the first lens group and the second lens group form a substantially afocal system, focusing is effected by moving the second lens group along the optical axis, and the first lens group has a front group of positive refracting power and a rear group of weak positive refracting power arranged in the named order from the object side.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.