Real image type zoom finder
US5216457A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 30, 1991 |
| Grant date | Jun 1, 1993 |
| Priority date | — |
| Expiry date | Aug 30, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B23/145
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A real image type zoom finder has a Porro prism for an erecting image arranged between an objective lens system and an eyepiece system, and a reflecting mirror or a movable prism constituting a portion of the Porro prism. The reflecting mirror or the movable prism is moved in a direction of an optical axis of the lens systems in accordance with distance information about a photographed object from a focal length detector, and/or information about the focal length of a zoom lens from a zoom focal length detector, thereby correcting parallax. The reflecting mirror may be composed of two overlapped mirrors constructed by a first mirror as a semi-transparent mirror arranged on the side of an objective lens and a second mirror composed of a total reflection mirror. In this case, the second mirror can be moved in the direction of the optical axis of the lens systems by a moving amount according to information about the focal length of the zoom lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.