| 摘要 |
Here is disclosed a range finder utilizing a line sensor of charge accumulation type, wherein photosensitive monitoring means is provided to monitor luminance of a scene to be photographed, an appropriate amplification factor is selected on the basis of integral value of charge accumulated by the photosensitive monitoring means, a video signal output from the line sensor and reflecting the luminance of the scene is amplified at the selected amplification factor, then the amplified video signal is computed and thereby a period required for charge accumulation in the line sensor is shorten independently of the scene's luminance. The amplification factor is selected on the basis of the period elapsing before the integral value exceeds a predetermined reference value, or by detecting a particular one of plural reference values that has been reached within the predetermined period or by resetting every time the reference value is reached and by counting the number of times by which the reference value has been reached within the predetermined period so that the relatively low amplification factors may be selected for the scenes of relatively high luminaries and the relatively high amplification factors may be selected for the scenes of relatively low luminaries.
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