Action and Sports Photography
Capturing great action and sports shots is all about freezing the action at the right moment. This means using a fast shutter speed of at least 1/250 second and, usually, 1/500 second or faster. To get these fast shutter speeds, you need a lot of light to reach the sensor. This is easy if you are photographing during the middle of the day in very bright sunlight, but it can become a problem when shooting in the evening or indoors in lower light.
To be able to shoot sports and action shots in low light, you need to use lenses that have a wide maximum aperture, like f/2.8 or f/4.0. These lenses can be rather expensive (some cost over $10,000), but for this type of photography you really need one for two reasons. First, if you want to freeze the action and use the higher shutter speeds, you need the large amount of light that these lenses allow.
Second, a wide maximum aperture enables you to create images with a shallow depth of field to make the main subject stand out against the background. Another perk of shallow depth of field is that it enables you to photograph through chain-link fences, which is very useful when photographing baseball or softball. Get as close to the fence as possible with a 100mm lens or longer and focus through it on the subject, making the fence essentially disappear.
Using a wide aperture lens close to a fence is a technique that also works well when photographing at a zoo.
Along with fast shutter speeds, having knowledge ...