| 摘要 |
PROBLEM TO BE SOLVED: To variably set the response speed of dimming by a user's desire, etc. SOLUTION: The optical image formed on an image pickup element 2 by the light from an object made incident through a diaphragm 6b of the automatic dimming circuit 1 is subjected to photoelectric conversion and is converted by a DC conversion means 3 to a signal of DC which is then inputted through a changeover means 4 to a phase correction section 5. In this phase correction section 5, a dimming signal subjected to the phase correction with the time constant by one phase correction circuit selected from the phase correction circuits 5A to 5D set at the time constants respectively varying the response speed at the time of dimming via a control means 7 from an instruction means 8 by a user is formed and is inputted to an operational amplifier 6a constituting the dimming means 6. The opening and closing quantity of the diaphragm 6b is regulated by the output signal compared with a reference value Vref, by which the operation of the dimming is executed in the phase correction circuit of the time constant selectively instructed by the user in the instructing means 8.
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