| 摘要 |
PURPOSE:To prevent delay of indication of low illumination due to a blind sector by detecting an image pickup signal corresponding to the limit of illumination of an object responsively, and indicating low illumination. CONSTITUTION:While the illumination of an object is decreased in the range of correction of a gain controlling circuit 11, image pickup signals to an operational amplifier 12 are controlled to nearly fixed level and do not become more negative than reference voltage E2. Output of the operational amplifier 12 when the gain of the gain controlling circuit 11 is maximum is restricted not to become larger than E1-VF by conduction of a diode D1. Accordingly, the operational amplifier 12 does not perform low illumination indication at the time of correcting operation. On the other hand, when the illumination of the object becomes lower than a certain level, the gain controlling circuit 11 does not amplify the image pickup signal to the limited value of correction. Accordingly, output of the operational amplifier 12 exceeds E1-VF, and shifts at a stretch to the maximum output voltage determined by the gain of the amplifier 12. Consequently, a light emission diode D3 conducts and emits light and indicates that illumination of the object is too low for photographing.
|
