if it is in the off state the control routine advances to step s10 in step s10 the state of the first switch 1 is checked once again if the first switch 1 is turned on the control routine returns to step s4 and if it is in the off state the control routine goes back to step 1 in step s5 the photographing lens 15 is initially driven on the basis of the first range value 1 l 0 in usual cases 300 msec are required for driving the lens 15 and this occupies most of the time lag in the autofocus camera in step s6 when the initial driving of the photographing lens 15 is completed the ired 9 is lighted once again and the range finding operation is performed thus obtaining a second range value 1 l 1 this second range value is stored in a memory m 1 not shown in step s7 when the range finding operation is completed the time count in step s3 is simultaneously stopped and the timer means outputs a time count value time count data u03b4t representing the time between the first and second range finding operations in usual cases since the amount of movement of the lens 15 varies in accordance with the object distance the velocity of the object can exactly be found on the.