A true lens is a single piece of glass (or other transparent substance) having one or more curved surfaces used in changing the convergence of light rays. What we commonly call a photographic lens is more accurately and technically called an objective, an optical device containing a combination of lenses that receive light rays from an object and form an image on the focal plane. However, dictionaries have come to accept the usage of the term lens to mean the entire photographic objective itself. A photographic lens will always be called a lens, even though it is not a lens, but has a lot of lenses in it. A camera lens collects and focuses rays of light to form an image on a digital camera s sensor or a traditional camera s film.Photo Tips
An imaginary straight line through the center of a lens.
The part of a lens that is cylindrical and that holds the lens elements.
A thin layer of transparent material applied to glass surfaces in a lens to control light reflections, reduce flare, and increase image contrast.
An accessory that attaches as a collar to the front of a lens to prevent stray light from striking the surface of the lens, causing flare. Many experienced photographers ensure that lens hoods are on their lenses at all times when in use, with the added benefit of protecting the lens from being accidentally scratched or damaged.