PURPOSE: To photograph a picture without blur, by detecting the relative movement between a subject and an image forming medium, and changing the exposure time to the image forming medium in accordance with said movement.

CONSTITUTION: Signals read out from the 1st horizontal transfer register 5 and the 2nd horizontal transfer register 8 are supplied to a comparator 52 respectively. The output of the comparator 52 is supplied to an integrating circuit 54 through an absolute value generating circuit 53. When the output of the integrated circuit 54 exceeds a fixed value, a comparator 55 decides that the blur of the picture signal is severe and supplies a signal to increase the shutter speed to an exposure controlling circuit 51, a means to control the exposure time. When the signal to increase the shutter speed is inputted to the exposure controlling circuit 51, the opening angle θ of a shutter 44 is changed so as to be decreased and a diaphragm 43 is opened.