6.7. TELEPHOTO LENSES
Telephoto lenses are perhaps Canon's most distinctive products, easily recognized wherever they are used. Whether it's a group of photographers at the Olympic Games or on the sidelines of the Super Bowl, photojournalists at a presidential press conference, or camouflaged war photographers in a battle zone, the long, white barrels are ever prevalent and always noticeable in every important and prominent event involving photography.
A telephoto lens is not always a zoom lens, although the terms are frequently used interchangeably. A telephoto lens can be a prime, or fixed, device, or it can be a zoom that ranges between minimum and maximum focal lengths. Telephotos, however, always magnify distance to make it seem closer than it is; furthermore, the longer the distance they magnify, the more compressed the images appear. They are excellent at creating narrow depth-of-field shots from far away, as in 6-20. The amount of telephoto magnification you need depends on how close you can get to your subject. If you're shooting at the sidelines of a football game, for example, you'll need a lens that's at least 300mm or more; pro field sports (for example, football and soccer) and wildlife photographers often use super-telephoto lenses of 400mm or higher because it is more difficult to get close to their subjects. On the other hand, if you're using a telephoto lens at a wedding, you probably won't need it to be longer than 200mm.