Zoom lens and imaging system incorporating it
US7382549B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 8, 2005 |
| Grant date | Jun 3, 2008 |
| Priority date | — |
| Expiry date | Dec 28, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention relates to a high-performance, high-zoom-ratio zoom lens that is reduced in length upon received at a collapsible lens mount. The zoom lens is a four-group zoom lens comprising a first lens group G1 of positive refracting power, a second lens group G2 of negative refracting power, a third lens group G3 of positive refracting power and a fourth lens group G4. For zooming from the wide-angle end to the telephoto end, the 1st G1 to the 4th lens group G4 are each operable to move with a change in the space between adjacent lens groups. The second lens group G3 comprises three lenses, and an aperture stop S located between the second lens group G2 and the third lens group G3, wherein the aperture stop is positioned nearer to the image side at the wide-angle end than at the telephoto end. The zoom lens satisfies conditions (1) and (2).7<(β2t·β3t·β4w)/(β2w·β3w·β4t)<15 (1)7<(β2t·β3t)/(β2w·β3w)<15 (2)Here, βnt is the magnification of an n-th lens group at the telephoto end, and βnw is the magnification of the n-th lens group at the wide-angle end.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.