Compact zoom lens system
US5726811A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 12, 1996 |
| Grant date | Mar 10, 1998 |
| Priority date | — |
| Expiry date | Dec 12, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/142
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A compact lens system is disclosed which includes a first lens group and a second lens group. The first lens group, which has an overall positive refractive power, includes a first meniscus lens, convex toward an object, and having a positive refractive power. Also included is a second biconcave lens having a negative refractive power, and a third biconvex lens which is connected to the second lens and which has a positive refractive power. The first lens group further includes a fourth biconvex lens which has a positive refractive power. The second lens group has an overall negative refractive power, and includes: a fifth concave lens having a positive refractive power; a sixth concave lens having a negative refractive power; and a seventh lens having a negative refractive power. The magnification of the system can be changed by varying a distance between the first and the second lens group in accordance with the following condition: EQU 1.1<(f.sub.bT -f.sub.bW)/(L.sub.T -L.sub.W)<1.24 where L.sub.W is the length of the zoom lens system at a wide angle position, L.sub.T is the length of the zoom lens system at a telephoto angle position, f.sub.bT is the back focal length at the te…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.