Photometric device built into viewfinder system for a single len

Details Photometric device built into viewfinder system for a single len Photometric device built into viewfinder system for a single len

1975-09-11

1977-05-03

Gonzales, John

354 56, 354155, 354225, G03B 708

Patent

active

040218236

ABSTRACT:
A through the lens (TTL) photometric function is provided by apparatus built into a viewfinder system for a single lens reflex (SLR) camera. As to the viewfinder function, an optical path is defined between the SLR focusing screen and a viewfinder eyepiece. A first prism, forming part of the optical path, has a plurality of faces, two of which serve to internally reflect light entering the prism so that the light emerging from the prism has been twice reflected. As to the photometric function, at least one separate optical path is defined for light emerging from the first prism at a peripheral position outside the finder field. In each separate optical path there is a second prism and a light receiving element with the second prism being arranged between the first prism and the light receiving element.

REFERENCES:
patent: 3513759 (1970-05-01), Kondo
patent: 3563149 (1971-02-01), Suzuki
patent: 3631784 (1972-01-01), Jurenz
patent: 3710699 (1973-01-01), Mitani
patent: 3788202 (1974-01-01), Wiessner
patent: 3864699 (1975-02-01), Tsunekawa et al.
patent: 3864702 (1975-02-01), Sugiyama et al.

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