Taking control of the shutter speed gives you the ability to freeze or blur motion
Choosing whether to capture moving subjects as sharply as possible, or with some blur, is a critical. For maximum sharpness you’ll need a fast shutter speed, usually 1/500 sec or less. At these speeds there needs to be plenty of light, or you have to increase the ISO (see page 38). appear static, so you need to use this technique with care. For the best results there needs to be some aspect of the subject that implies movement, so look for moments when your subject leaves the ground, kicks up dust or spray, or is in a position that would be impossible if it were standing still.
When using fast shutter speeds to freeze movement, you need to watch the aperture displayed in the viewfinder, and if it starts to flash (and the exposure scale displays a negative value), it means that there isn’t enough light for a correct exposure, even at the widest aperture available on your lens. In this case you will need to set a higher ISO – do it in stages until the display stops flashing. Nikon SLRs offer maximum shutter speeds of 1/4000 sec or even 1/8000 sec, but these speeds are rarely useful in real-world situations. Most moving subjects can be frozen by speeds of 1/2000 sec or slower, and you’ll need extremely bright conditions, a wide aperture and a high ISO setting to use shutter speeds faster than this. It’s much better to use high-speed flash to freeze subjects like water splashes or other extremely fast-moving objects.