PURPOSE: To make the automatic dimming of an incident light quantity to a photoreceptor element possible and to effectively prevent a blooming phenomenon by controlling the transmitting light quantity of a liquid crystal filter in accordance with the level of an output signal from the photoreceptor element.

CONSTITUTION: An optical image formed on the image pickup surface of a solid- state image pickup element 4 is converted into electric signals corresponding to each picture element and supplied to a video processing section 6 and, at the same time, supplied to an A/D converter 13 where the electric signals are converted into digital signals in accordance with their level. The digital signals are converted into 4-bit signals by an encoder 14 and the 4-bit signals are added to a multiplexer 15 where the 4-bit signals are switched four pieces at a time and inputted into a liquid crystal driving circuit 12. The output voltage of the circuit 12 is applied to a liquid crystal filter 8 installed to the front face of the image pickup element 4 and the light shielding section of the filter 8 is controlled. Thus the incident light quantity is adjusted.