This can be achieved by following these steps.

☛ Set the lens to full wide angle view.

☛ Set the physical focus of the lens to infinity (clockwise viewed from the front).

☛ Aim the camera at an object at least 30 Meters away.

☛ Release the camera back focus mechanism.

☛ Adjust the back focus to obtain optimum clarity.

☛ Zoom the lens in to full telephoto and focus on a nearby object.

☛ Keep this object in view as you slowly zoom out and if all is set correctly it should remain in focus (track).

☛ Secure the back focus mechanism.