Single-lens reflex camera light measurement and exposure control

Details Single-lens reflex camera light measurement and exposure control Single-lens reflex camera light measurement and exposure control

1981-01-23

1982-03-30

Hix, L. T.

354 31, 354 60E, G03B 310, G03B 7099, G03B 726

Patent

active

043221424

ABSTRACT:
An electrical shutter type TTL single-lens reflex camera, with a movable mirror diagonally located within the photographic optical path to project object light to a viewfinder system during object observation and retractable from the optical path during photographic exposure, incorporates a light measurement device with a first light measuring element arranged for average light measurement of the light reflected from the movable mirror during object observation, at least part of the movable mirror being made transparent, or of a half mirror, to divide the object light into reflected light and light projected through the plane of the mirror. A second light measuring element is located to carry out spot metering on an object from the light projected through the plane of the movable mirror during object observation. A third light measuring element is located to receive reflected object light from a shutter curtain surface and/or the film surface for selection of average light measurement and spot metering on the object during photographic exposure. A manually operable selector selectively connects either the first or second light measuring element to an exposure information indicating device. The third light measuring element is adapted to be changed from average light measurement or to spot metering and to provide respective outputs representative thereof, such that exposure control with average light measurement or spot metering is obtainable from an exposure control circuit responsive to either output of the third light measuring element. In response to the selection of the first light measuring element by the manually operable selector, the third light measuring element is changed over for average light measurement, and in response to the selection of the second light measuring element, the third light measuring element is changed over for spot metering.

REFERENCES:
patent: 4019191 (1977-04-01), Miyata
patent: 4075640 (1978-02-01), Veda et al.
patent: 4083056 (1978-04-01), Nakamura et al.
patent: 4104654 (1978-08-01), Maitani et al.

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