Zoom lens apparatus of two-lens group structure
US5267085A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 1992 |
| Grant date | Nov 30, 1993 |
| Priority date | — |
| Expiry date | Jan 6, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/142
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In a zoom lens device of a two-lens group structure, positive and negative lens groups are sequentially arranged from a photographing field side. The zoom lens device has a controller for controlling a rear focusing operation for moving the negative lens group on a high magnification side. The controller also controls one of an entire drawing-out focusing operation for moving the positive and negative lens groups, and a front focusing operation for moving the positive lens group on a low magnification side. The high and low magnification sides are respectively set to telescopic and wide angle sides. A focal length of the zoom lens device is increased on the high magnification side and is decreased on the low magnification side. Thus, a zoom ratio is increased and a lens drawing-out amount is reduced on the telescopic side so that the zoom lens device can be made compact.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.