surface with more than one radius of curvature (i.e., the surface does not form part of a sphere). The aspherical elements of a lens help compensate for many lens aberrations common in simpler lens designs. Aspherical elements are particularly important for wide-angle lenses, since they are prone to distortion.
See “A Quick Guide to Digital Cameras” in the Quick Reference section of Webopedia.
See also Megapixel.net for news, reviews and a active community for digital camera and photography enthusiasts.