Telephoto and Zoom Lens
The telephoto lens
At the opposite end of the scale is the telephoto lens, loosely described as anything with a focal length greater than a standard lens. The telephoto is most useful for making distant subjects much bigger in your viewfinder and cropping out unwanted peripheral detail.
In addition to travel, sports and architectural photography, the telephoto is extremely useful for portrait photography, as little distortion occurs. All fashion magazine front cover photographs are taken with a long telephoto lens because an effect called foreshortening creates a very flattering result. With foreshortening, the physical distances between near and far elements become much more compressed and the opposite of the wide-angle effect is created.
Telephoto lenses are physically longer than standard or wide-angle lenses. With this increase in size comes extra weight and potential problems with the photographer’s balance. Focussed on a tiny object in the distance, an extended telephoto lens will start to wobble, making it essential to grip the camera steady or use an extra support like a tripod. For long lens work, a good idea is to choose a faster shutter speed like 1/250s to avoid the unwanted effects of camera shake.
The zoom lens
Many digital cameras are sold with a zoom, which has a variable focal length such as 7.85-32mm. A zoom lens lets a photographer have the freedom to frame subjects set at variable distances. Zoom lenses are essentially stepless, enabling the photographer to carefully frame and compose different subject variations from the same position.
This is particularly useful when close access to your subject is out of your reach – like detail on the upper reaches of a building. At the shorter 7.85mm end of this scale, the lens is wide-angle; at the longer 32mm end of the scale, the lens is telephoto. Many zooms have a maximum aperture that is not as wide as a prime lens, such as f4 instead of f2.8. In practical terms, this is less useful for shooting in low light and achieving shallow depth of field effects. The maximum aperture setting is rarely constant across a zoom’s range, often changing from f4 at the wide-angle end to f5.6 at the telephoto end. Macro zooms, another potential feature to look out for, are specialised lenses offering a tool for close-up photos.
