Photographing action in poor light presents a significant challenge. The lower the level of the light and the faster the action, the more difficult photography becomes. The approach a photographer chooses will inevitably depend upon the type of images required. Freezing rapid movement in low light conditions may be possible only with a high ISO setting and wide-aperture lenses. Prime lenses may be a better choice than zooms from this point of view.
Movement can sometimes be "stopped" by using the fastest possible shutter speeds, but this approach implies the use a high ISO speed, a wide aperture and limited depth of field. Blurring can also be reduced by careful panning of the camera during the exposure. A shutter speed of 1/500 second used in conjunction with smooth and appropriate panning may be sufficient to produce a sharp image of a racing car or an aircraft in flight, yet still render the background blurred to retain the impression of movement.
Flash can also be used to freeze movement. The pulse of light emitted by a standard flashgun is of very short duration - perhaps only 1/10,000 second. Provided the subject is within the range of the flashgun, it is therefore possible to effectively freeze quite rapid motion. Rear-curtain flash is useful to record any ambient light blurring as a trail which follows the subject in a natural manner.
Another approach is to accept that a subject will be blurred and use this as a feature of the image to convey the impression of speed. The amount of blurring recorded is determined not only by the shutter speed and the speed of movement of the subject, but also the direction of the movement relative to the camera. Movement across the field of view will produce more blurring than the same motion towards or away from the camera.
Achieving sharp focus on a fast-moving subject in poor light is another significant challenge. Where the movement of the subject is predictable and repeated, as in the case of a pole-vaulter, the best approach is to manually pre-focus the lens on the peak of the action. The shutter release must then be pressed a split-second prior to the athlete reaching the required position. Waiting until the peak of the action is seen in the viewfinder will prove too late. An alternative approach is to learn to follow the movement of the subject whilst adjusting the focus. Some modern cameras are equipped to perform this function automatically. Autofocus may work well in some cases, but may prove ineffective in others. Inevitably, practice and experience are crucial.