Technique for determining whether to use fill flash illumination

Details Technique for determining whether to use fill flash illumination Technique for determining whether to use fill flash illumination

1990-09-20

1992-06-09

Perkey, W. B.

354422, 354432, G03B 1503

Patent

active

051211556

ABSTRACT:
Apparatus, and an accompanying method, for use in a photographic camera for determining whether to utilize fill flash illumination in photographing a current scene. Specifically, fill flash illumination is used if both an initial value of the scene lighting contrast, based upon measured near primary and distanct primary (or background) subject lighting levels, indicates that a distant primary or background subject is lighter than a near primary subject and use of fill flash illumination will reduce the scene lighting contrast from its initial value. Fill flash illumination will be inhibited if the distant primary or background subject will not be adequately illuminated to generate a proper exposure thereof or if the near primary subject will be excessively illuminated relative to the distant primary or background subject so as to cause a reversal in the scene lighting contrast to occur. However, if an energy saving flash unit is being used, the output power of the flash can be appropriately reduced to a level sufficient to eliminate a reversal. Alternatively, a programmable shutter, if it is available, can be set to a different opening for a flash exposure than for an ambient exposure in order to prevent the scene lighting contrast from reversing.

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