Optical system for indication in the viewfinder of single-lens reflex camera
US4118722A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 20, 1976 |
| Grant date | Oct 3, 1978 |
| Priority date | — |
| Expiry date | Oct 20, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B17/20
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The disclosure describes a compact and inexpensive optical system to be built in the viewfinder of a single-lens reflex camera for reading, in the viewfinder, an optical image of an indication element provided on the outside of the viewfinder. The optical system comprises a pentagonal Dach-prism having a light transmitting portion provided thereon, a first reflecting member and a second reflective member. The first and second reflective members have a specific positional relation to each other and also relative to the light transmitting portion of the prism so that an information carrying light beam coming from the indication element may reach the eyepiece of the viewfinder along a shortest possible light path.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.