The stop-action shot
In order to give an image a stop-action look, you’ll either need to use your camera’s sports/action mode (indicated by the running figure on the basic shooting mode dial), or your shutter-priority mode to set a fast shutter speed. In this mode, denoted by the Tv (time value) or S (shutter) mode on your shooting dial, you set the desired shutter speed and your camera will automatically set the aperture to get the best exposure. By using a shutter speed of at least 1/500—and especially at 1/1000 to 1/5000 second—you can freeze nearly all activities, including those that happen too quickly to be perceived by the human eye. A person will appear to be suspended in mid-air, while water droplets seem frozen in space. You’ll also need good lighting in order to freeze motion, so it’s best to shoot these images in a well-lit interior venue or on a sunny day. I also advise using an ISO setting of at least 400 to help stop action as well.
~Lynne Eodice from her article How-To: Capturing Action & Motion