Patent
1976-12-07
1978-06-27
Hix, L. T.
354 59, 354154, G03B 708, G03B 1912
Patent
active
040978761
ABSTRACT:
A light meter for a SLR camera implements both initial exposure time display and automatic exposure time control using a single light sensing element 8. The reflex mirror 3is formed as a beam splitter or half-mirror. When lowered, some of the viewfinder light passes through the mirror and is reflected onto the sensing face of the element 8 by the shutter curtains 9 or 10 to enable the time display function. When the mirror is raised and the lens diaphragm 2 reduced, the light is again reflected from the curtains and/or film surface 11 onto the sensing element face to enable the time control function.
A hinged shield 13 may be provided to block light from entering the camera box 12 via the rangefinder lens 7 when the mirror 3 is raised, and dual sensing elements 8, 8' may be employed together with an additional reflecting mirror 15 and an angled or concave shield 13 ' to effect a uniform vertical light distribution sensitivity in both the display and control modes.
REFERENCES:
patent: 3165992 (1965-01-01), Ando
patent: 3730063 (1973-05-01), Kobayashi et al.
patent: 3791276 (1974-02-01), Ueda et al.
patent: 3842424 (1974-10-01), Tsunekawa et al.
patent: 3872484 (1975-03-01), Hashimoto et al.
patent: 3994001 (1976-11-01), Maitani et al.
Miyata Katsuhiko
Uno Naoyuki
Asahi Kogaku Kogyo Kabushiki Kaisha
Hix L. T,.
Perkey William B.
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