Exposure control apparatus for lens-shutter type camera

Details Exposure control apparatus for lens-shutter type camera Exposure control apparatus for lens-shutter type camera

1989-02-27

1990-02-06

Perkey, W. B.

354435, 354137, 35419511, G03B 7097, G03B 1716, G03B 1503, G03B 500

Patent

active

048991910

ABSTRACT:
A first table for storing a correspondence between an exposure value and a shutter-blade aperture time and a second table for storing a correspondence between an exposure value and an effective exposure time are prepared at a specific focal length. A correction circuit corrects the exposure value for the first and second tables in accordance with a focal length of a lens. A comparator compares the corrected exposure value for the first table with a full-open exposure value to determine whether correct exposure can be obtained before or after a full-open of the shutter blades. A selector supplies the corrected exposure value to the first table when correct exposure is obtained before the full-open of the shutter blades, and supplies the full-open exposure value when correct exposure is obtained after the full-open. The shutter-blade aperture time and the effective exposure time output from the first and second tables are input to a shutter-close timing calculator. When correct exposure is obtained before the full-open of the shutter blades, a shutter-close timing is determined using the shutter-blade aperture time. When correct exposure is obtained after the full-open, the shutter-close timing is determined using a sum of the effective exposure time and a half of the shutter-blade aperture time obtained from the first table on the basis of the full-open exposure value.

REFERENCES:
patent: 4724455 (1988-02-01), Suzuki et al.

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