| 摘要 |
PURPOSE:To obtain always stable picture quality by providing an aperture value detecting means extracting a detection signal in response to the aperture of a lens system and a picture quality adjusting circuit whose frequency characteristic is controlled variably by the detection signal and outputting an image pickup signal while providing the frequency characteristic. CONSTITUTION:The frequency characteristic of the picture quality adjusting circuit 9 is controlled variably so that the relative level increase of a high frequency to a low frequency is larger as the F value of the aperture is increased. The change in the frequency characteristic of the picture quality adjusting circuit 6 has nearly opposite characteristic in the relation between the aperture and modulation MTF. A video signal extracted from a video processing circuit 5 is fed to the picture quality adjusting circuit 9, after the frequency characteristic as shown in figure is obtained, the result is outputted to an output terminal 8. The frequency characteristic of the picture quality adjusting circuit 9 is controlled variably by the output signal of an aperture drive circuit 7, and the output signal of the aperture drive circuit 7 is a signal having a level in response to the F value. Thus, the frequency characteristic of the picture quality adjusting circuit 9 is controlled variably in response to the F value. |
