PURPOSE: To use a DC driven automatic iris lens under a high illuminance without providing a mechanical stopper by suppressing hunting for the high illuminance.

CONSTITUTION: The output signal of a CCD 2 has the noise eliminated by an S/H circuit 3 and is processed by a process 4 to output a video signal 5. The output of the S/H circuit is detected by a detector 6 and is subtracted from a set voltage E2 by a subtractor 7, and this output voltage E3 is applied to a coil L1 of an automatic iris lens 1 to drive and open/close an iris. The detection output of the detector 6 is inputted to comparators 8 and 9, and if it is higher than a set voltage E4 or lower than a set voltage E5, comparators output signals respectively, and OR is operated in an AND operating circuit 10 after integration, and the output is integrated by an integrator 11 and is applied to the base electrode of a transistor 12. The driving voltage E3 from the subtractor 7 is so limited that it is not reduced to the emitter voltage of the transistor or lower, and the drop of the voltage applied to the coil L1 is suppressed, and a stop is controlled to prevent the occurrence of hunting.