A wide range of camera lenses are available for every type of photography and are vital to capturing great shots.
A camera lens is a vitally important component in photo quality. It gathers light and is used to focus on a particular subject. Different types of photography often call for certain lens characteristics. Lenses may form an integral part of the camera body or come separately. The lens functions together with the film or digital image sensor to capture an image.
Fixed Lenses
Most compact point-and-shoot cameras feature a built-in lens that cannot be removed from the camera. This is usually a zoom lens that offers a certain level of optical magnification. It is sometimes possible to fit additional lenses or filters on the front of fixed lenses. These may offer wide-angle, telephoto or macro shooting or affect the quality of the light entering the camera.
Interchangeable Lenses
Most film and digital SLR (single lens reflex) cameras can be fitted with a range of lenses. Each camera has a specific mount system. Any lens designed for that mount can be attached. Converters are available allowing otherwise incompatible lenses to be fitted. This may cause automatic camera functions to stop working correctly. Manufacturing quality varies greatly. Larger lenses using higher quality parts are usually more expensive. Most lenses have a thread at the front for attaching lens hoods and filters.
Focal Length
Every lens has either a fixed or minimum and maximum focal length. This determines the angle of view and magnification. Single focal length (prime) lenses have a single focal length. Zoom lenses cover a focal length range. Most fixed lens cameras operate the zoom lens internally while SLR cameras allow the user to adjust the focal length of a zoom lens by rotating the barrel by hand. This offers adept photographers more accurate and faster control. Lenses with different focal length ranges are often categorized as wide angle, standard, telephoto or super telephoto, offering a quick guide its primary use.
Aperture
The aperture of a lens determines how much light can enter it. Wider apertures allow more light into the camera. A wide aperture is often associated with a narrow depth of field. This is characterized in photographs by a blurred background (bokeh). Narrow apertures produce a wide depth of field with much more of the image appearing in focus. Aperture also affects shutter speed. Lenses capable of very wide apertures are often called "fast" lenses. They are usually much more expensive.
Cropping Factor
The cropping factor is an important consideration in digital photography. It compares the size of the camera's image sensor with that of 35 mm film. The cropping factor affects the equivalent focal length of a lens. Compact cameras often have a very high cropping factor. SLR cameras without full frame sensors have a moderate cropping factor. A camera with a cropping factor of 1.6 would cause a 50 mm lens to function as an 80 mm one. A high cropping factor is advantageous in telephoto lenses but can make wide-angle lenses far less effective.
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