Zoom lens
US5100223A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 21, 1990 |
| Grant date | Mar 31, 1992 |
| Priority date | — |
| Expiry date | Jun 21, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens of this invention comprises in successive order from the object side a first group having a positive refractive power and fixed, a second group having a negative refracting power for effecting a variation of image magnification by moving on the optical axis, a third group having a positive power for effecting a light condensing action and fixed, and a fourth group moving on the optical axis so as to keep an image surface position to be changed in response to a move of the second group and a move of the object in a constant positional relation with the reference surface. Comparatively large air space is provided between the third and fourth groups of the zoom lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.