Aspherical (ASP)
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Not a continuous curve. Refers to non-spherical elements in lenses designed to compensate for distortion by having different curves on individual elements. Nikon introduced the first photographic lens with aspherical lens elements in 1968. Allows for more compact wide angle lenses, lighter and better performing than others with only spherical elements. When applied to Nikkor lenses the term implies excellent performance with absence of coma and other aberrations, even at their widest aperture.
