To focus a camera on objects at different distances, the converging lens is moved toward or away from the image sensor, so a sharp image always falls...

To focus a camera on objects at different distances, the converging lens is moved toward or away from the image sensor, so a sharp image always falls on the sensor. A camera with a telephoto lens (f = 320 mm) is to be focused on an object located first at a distance of 3.5 m and then at 50.0 m. Over what distance must the lens be movable?