Zoom lens having three movable lens groups
US4306776A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 3, 1979 |
| Grant date | Dec 22, 1981 |
| Priority date | — |
| Expiry date | Dec 3, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/1441
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In the disclosed zoom lens of the mechanical compensation type, a first movable lens group, a second movable lens group, a third movable lens group and a fixed lens group are located in sequence from the object end. The first, second and third lens groups are simultaneously moved along the optical axis independently of each so as to change the focal length. The first movable lens group is placed closer to the image at the end of the wide angle position rather than at the end of the telephoto position, while during zooming, the axial movement of the first movable lens from the extreme wide angle position to the extreme telephoto position is smaller than that of the third movable lens group. On the other hand, during focusing, the second and the third lens groups are fixed, while the first movable lens group is moved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.