The flash is created when a high electrical voltage is discharged into a slender glass tube filled with xenon gas. The electricity excites the gas and it outputs a blitz similar to lightning. This blitz is extremely short. The duration of the flash can be from 1/500 to 1/100,000 of a second. Most likely your unit operates around 1/2000 of a second. Because the blitz is fast, it is able to freeze fast action. High speed flash can freeze and thus capture such things as hummingbird wings. It is unlikely that your flash will accomplish this super feat, but it likely will freeze common sports activity.

The key to success is: The flash must synchronize with your camera’s shutter. Check your camera manual. There will be one shutter speed, usually marked with an icon of a lightning bolt. This marks the fastest shutter speed that is compatible with electronic flash. Likely, slower shutter speeds are also compatible.

One problem is: The designated max shutter speed might only be 1/125 of a second. This is not terribly fast. What can happen is: The flash fires and freezes the action, but the scene is also being illuminated by ambient light, so both light sources record the image. The result is much like a double exposure. The image of the frozen subject illuminated by the flash records as does an image illuminated by existing light. When this happens we sometimes get a frozen image superimposed atop a streaky image.

We get blur from subject motion and from camera motion. A fast shutter or a rapid flash mitigates. Combine a fast flash with a slow shutter and likely you will get both the streaky image combined with camera shake.

So the bottom line is: An electronic flash can and will freeze subject motion. You need to experiment and find out how subjects are rendered using this wonderful tool.