Wide-angle zoom lens
US5724192A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 25, 1995 |
| Grant date | Mar 3, 1998 |
| Priority date | — |
| Expiry date | Sep 25, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143103
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A wide-angle zoom lens system which can reduce variation in aberrations and obtain a sufficient back focus distance at the wide angle position by making the view angle wide at the wide angle position and making the whole length of the optical system short at the telephoto position. The wide-angle zoom lens system, includes a first lens group having a positive refractive power; a second lens group having a positive refractive power; and a third lens group having a negative refractive power, the distances between the first lens group, the second lens group, and the third lens group change during zooming, wherein the first lens group includes a first lens having a negative refractive power with a shape of a meniscus lens concave toward an object, a second lens having a positive refractive power and a third lens having a negative refractive power, the first, second and third lens groups are made of spherical lenses, the distance between the first and second lens groups is increased, and the distance between the second and third lens groups is reduced; and wherein the zoom lens system has the following characteristics: -0.5<(R.sub.1a1 +R.sub.1a2) / (R.sub.1a1 -R.sub.1a2)<-2.0 wherein R.…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.