An auto-focus system for a video camera having a zooming function includes an auto-focus signal generator for generating an auto-focus signal of the video camera. In particular, unlike conventional systems, auto-focus is accomplished by moving a master lens of the zoom lens system. A motor is coupled to at least a part of the master lens for this, and a motor controller performs the auto-focus operation by controlling the motor in accordance with the auto-focus signal. Further, a switch is provided which is changeable selectively between a first and a second mode instructing photographing over a normal distance range and over a macroscopic range respectively. A master lens controller controls the motor controller to decide a movable range of the master lens in accordance with the selected mode of the switch and to thereby control the motor controller to move the master lens within the decided movable range.