Zoom lens system
US6028717A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 12, 1998 |
| Grant date | Feb 22, 2000 |
| Priority date | — |
| Expiry date | Jun 12, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/143105
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Sequentially from the object side: a first lens unit having positive optical power; a second lens unit having negative optical power; and a third lens unit having positive optical power, wherein said first and second lens units normally move in opposite directions whereas the third lens unit moves linearly to the object side during zooming from the wide angle end to the telephoto end, and wherein the following conditional equation is satisfied: EQU 0.2<M1/Z<2.0 where M1 represents the amount of movement of the first lens unit during zooming from the wide angle end to the telephoto end, Z represents the zoom ratio (fT/fW), fT represents the overall focal length of the total system at the telephoto end, and fW represents the overall focal length of the total system at the wide angle end. Alternatively, the first lens unit moves to the object side, said second lens unit is stationary, and said third lens unit moves linearly to the object side during zooming from the wide angle end to the telephoto end, and wherein the following conditional equation is satisfied: EQU 0.2<M1/Z<3.0.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.