Zoom lens system
US5872659A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 21, 1997 |
| Grant date | Feb 16, 1999 |
| Priority date | — |
| Expiry date | Jan 21, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/145113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom lens system of the present invention comprises, from the object side, a first positive lens unit, a second negative lens unit, a third positive lens unit, a fourth positive lens unit and a fifth negative lens unit, wherein all of the lens units move toward the object during zooming from the shortest focal length condition toward the longest focal length condition, and said zoom lens system meets the following conditions. EQU -0.30<f2/f1<-0.10 (1) EQU 1.25<.beta.5T/.beta.5W<2.00 (2) EQU 0.25<(.beta.5T.multidot..beta.2W)/(.beta.2T.multidot..beta.5W)<0.65 (3) EQU -1.20<f12W/fw<-0.60 (4) where, f1: focal length of the first lens unit; f2: focal length of the second lens unit; fw: shortest focal length of the entire system; .beta.5W: horizontal magnification of the fifth lens unit in the shortest focal length condition; .beta.5T: horizontal magnification of the fifth lens unit in the longest focal length condition; .beta.2W: horizontal magnification of the second lens unit in the shortest focal length condition; .beta.2T: horizontal magnification of the second lens unit in the longest focal length condition; and f12W: combined focal lengths of the first lens unit and the second l…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.