Zoom lens system
US5978152A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 12, 1998 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Feb 12, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/173
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A very compact zoom lens system is provided which has a zoom ratio of 10.times., a bright f-number of 1.4 and a wide angle of view of 59 degree or greater although having a fewer number of lens. The zoom lens system comprises from the object side to the image side: a fixed first lens unit having a negative power lens, a positive power lens and a positive power meniscus lens; a second lens unit having an aspherical surface, having a negative power lens, a negative power biconcave lens and a positive power lens and performing zooming by moving; a fixed third lens unit having an aspherical surface and having a positive power lens, a positive power lens and a negative power lens; and a fourth lens unit having an aspherical surface, having positive power and moves according to zooming and a movement of an object point. The image side surface of the most image side lens of the third lens unit is a concave surface having strong power to the image side. When the focal length at the wide-angle limit is fw, the angle of view at the wide-angle limit is .omega., the focal length of the first lens unit is f1 and the focal length of the second lens unit is f2, the following condition is satisfie…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.