Compact-size zoom lens system
US5153777A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 1990 |
| Grant date | Oct 6, 1992 |
| Priority date | — |
| Expiry date | Dec 5, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/1421
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A compact-size, light-weight, low-cost zoom lens system with high optical quality is achieved by using a ray restrictor placed at the most object side of the zoom lens system. In one type, the ray resistor shifts toward the object at a speed different from that of the most object side lens of the zoom lens system as the zoom lens system is zoomed toward the longest focal length, which effectively blocks harmful rays causing coma flare in the peripheral area. In another type, the aperture diameter of the ray restrictor varies according to a zooming operation. The ray restrictor of any type is especially effective when used in a zoom lens system composed of two lens groups. By introducing one or more aspherical surfaces satisfying a certain condition (or conditions) in the zoom lens system, various aberrations are further favorably corrected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.