PURPOSE:To make an automatic focus adjustment with high precision, by providing a focus matching device in a feedback loop, and adjusting minutely the optical path length between a subject and the photodetection surface of an image pickup element, and making the amplitude of a high frequency component obtained from the image pickup element maximum. CONSTITUTION:The vertical synchronizing signal of the synchronizing signal generator 10 of the automatic focus matching device is frequency-divided by (n) through a frequency divider 19 for reference signal generation and an oscillator 20 is operated by its frequency division output to minutely move an optical-path length varying element 21 which is arranged between the lens 6 and image pickup tube 7, and uses glass and varies the optical path length. The minute movement causes variation in amplitude at a reference frequency obtained by dividing the frequency of the high frequency component of the output signal of the image pickup tube 7, its amplitude component is detected by a reference frequency component detecting circuit 16, whose detection signal is detected synchronously to verify the driving direction of the focus matching device. Then, the feedback loop is constituted so as to make the high frequency component maximum, and while focus matching is stabilized, the focus is adjusted automatically with high precision.
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