Zoom lens system
US4516839A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 29, 1985 |
| Grant date | May 14, 1985 |
| Priority date | — |
| Expiry date | Jun 29, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144511
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens system comprising a first lens group of a negative refractive power, a second lens group of a positive refractive power located on the image side of the first lens group with a first variable air space, a third lens group of a negative refractive power located on the image side of the second lens group with a second variable air space and a fourth lens group or unit of a positive refractive power located on the image side of the third lens group with a third variable air space is provided. The first and third variable air spaces are reduced and the second variable air space is increased in accordance with the increase of the focal length of the whole lens system during the zooming. The absolute value of the focal length of the third lens group is greater than that of the second lens group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.