The shapes of the surfaces of virtually all glass lens elements from the
beginning of optics have been sections of spheres. Optical designers
realized from very early on that other shapes could be used to improve
lens performance and/or reduce elements. However, there was never any
process developed to produce them at commercially sustainable prices
until recently. It was also not practical to design complex
non-spherical surfaced lens elements until the advent of relatively
powerful computers. I believe the biggest use in photography is in
molded plastic lenses in disposable cameras and cheap point and shoots.
Disposables might not exist without this technology which allows
incredibly cheap lenses to form sharp images. At the other end of the
spectrum, aspherical elements are used in many recent zoom designs. I
think they are also molded, but glass. Even now, most surfaces in even
the most sophisticated designs are still spherical.
Moose
nizora wrote:
Could any one help with the explanation of what aspherical element is.
Many thanks inadvance,
Rob
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