Inner focusing zoom lens system
US5528423A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 19, 1994 |
| Grant date | Jun 18, 1996 |
| Priority date | — |
| Expiry date | Oct 19, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/144113
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention relates to a zoom lens system used for photo-taking in a 35 mm single lens reflex camera. The zoom lens system consists of, from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power. Zooming from a wide-angle side to a telephoto side takes place by moving all of the first lens unit through the fourth lens unit to the object side. Focusing on an object at a short distance is performed by moving the second lens unit to the object side.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.