Zoom type of finder optical arrangement
US5448411A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 2, 1993 |
| Grant date | Sep 5, 1995 |
| Priority date | — |
| Expiry date | Jul 2, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B23/145
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention is directed to a zoom type of finder optical arrangement which, even when the magnification of finder is increased by changing the focal length of the eyepiece system, is less likely or unlikely to undergo aberration fluctuations and kept stationary in respect of the eye point location, and comprises an objective lens system a of positive refracting power, reflecting members b and d for image erection, and an eyepiece system of positive refracting power, said eyepiece system comprising a lens unit f of positive refracting power and a lens unit g of negative refracting power, and moved along the optical axis in such a way that the air separation between both the lens units becomes wider, thereby altering the focal length of said eyepiece system to change the magnification of finder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.