| 摘要 |
PROBLEM TO BE SOLVED: To improve temporal resolution of an iris. SOLUTION: A mean luminance level is calculated, on the basis of an image pickup signal detected within a period, when a luminance level is measured from the imaging signal and opening/closing of the iris provided to an optical lens system is controlled, on the basis of the calculated mean luminance level. When multiplying the temporal resolution of the iris p fold, a value adding an actually measured average luminance level to a luminance level change for a measurement period, predicted by an iris change per unit time under reference illuminance and an external illuminance at that time, is used for the control signal of the iris. Furthermore, an opening/closing control period of the iris is set to 1/p. Since in this way, the measurement period can be reduced to 1/p, the iris can be controlled with very short cycles, the temporal resolution can be enhanced.
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