The lens (also called objective) is an optical system which is attached to the camera used for the exposure. While a pinhole camera has a tiny hole, “regular” cameras use lenses for the exposure- and shutter-settings.

There are many different lenses to choose from. They can be distinguished from their focal length and lens speed. Depending on the focal length, they are called wide-angle lenses or telephoto lenses.

When it comes to point-and-shoot cameras, the lens is fixed on the camera, but the newer ones support replaceable lenses.

_{A typical lens for D-SLRs}

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