| 摘要 |
PURPOSE:To obtain a sharp record and to eliminate an error in photography by providing a light quantity sensor which detects the quantity of light from an original and controlling a recording medium and the quantity of exposure of an image reading means on the basis of information on the quantity of light from the light quantity sensor. CONSTITUTION:In general, an original has variance in density individually and the variance in density of the original is measured by the light quantity sensor 24. Then, an aperture setting circuit 31 determines a proper aperture value on the basis of both signals from a film sensitivity setting switch 32 and the light quantity sensor 24 on the side of a microfilm F and the value is set by moving the level, etc., of a stop 25. Further, a readout part 15 varies the gain of an amplifier 27 with the signal of the light quantity sensor 24 to eliminate under-exposure and over-exposure, thereby outputting a proper signal even for a half-tone original, etc. Further, a slit for exposure adjustment is provided between a solid-state image pickup element 26 and a half-mirror 12 and the size of this slit may be adjusted with the signal of the sensor 24 independently of the stop 25 to obtain a proper read signal.
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