| 摘要 |
A photographic camera includes exposure control apparatus for determining automatically if the camera is adjusted to achieve a suitable exposure. This determination is made taking into account the exposure latitude of film in the camera. The control apparatus includes film data-retrieval apparatus for receiving both film speed and film exposure latitude data. A light-level sensing circuit determines scene brightness, and diaphragm and shutter control mechanisms provide data relating to the aperture size and shutter speed, respectively, at which the camera is set. A microprocessor computes an exposure value that is based on scene brightness and film speed. The microprocessor then uses the computed exposure value to compute a range of acceptable exposure values corresponding to the film exposure latitude. The microprocessor also computes an exposure value that is anticipated based on the aperture size and shutter speed at which the camera is set. The microprocessor compares this anticipated exposure value to the computed exposure value range and provides for activation of an indicator to signal a camera operator as to whether or not the camera is adjusted so as to achieve a suitable exposure.
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