Optical exposure measuring system for photographic cameras
US4181412A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 15, 1978 |
| Grant date | Jan 1, 1980 |
| Priority date | — |
| Expiry date | Feb 15, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B7/09972
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical system for the metering of illumination in photographic cameras, in particular mirror-reflex cameras, which makes use of a photodetector with a light-sensitive surface small in comparison to the image area to be metered and which is mounted in the lower camera space. A honeycomb mirror consisting of a multitude of convex or concave mirror elements is mounted behind the reflex-mirror which is partly transmitting. The honeycomb mirror when it is in the metering position is located in front of the film plane and is moved together with the reflex-mirror out of the way of the beam path before the picture is taken, the mirror elements of the honeycomb mirror being slanted so that the center of every individual element reflects the principal rays toward the photodetector. The curvature of the mirror elements is such that the outermost peripheral rays from the objective are reflected from the rims of the mirror elements toward the photodetector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.