Slow panning is a fantastic way to convey movement, especially in low light levels when freezing the action isn’t a possibility. Some subjects cry out for this treatment. Photograph a moving vehicle with a fast shutter speed and it will look parked; use a slow shutter speed and it will render as an unrecognisable smudge. Panning, or moving the camera to keep up with a moving subject, will create motion blur in the background but your subject will be more or less sharp, depending on the nature of the movement. The shutter speed you need depends on the speed of the thing you are panning. Anything from 1/2 to 1/30 sec is a good starting point, but experiment so you are familiar with the technique. Panning with a telephoto will give a flatter effect, while panning a subject coming towards you with a wide lens will make it appear to explode! The ability to select slow speeds at will is one of the main reasons why I never use Auto ISO.
EXPOSURE 1/125 sec, f/7.1, ISO160
LENS Nikon 17-35mm f/2.8