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what is aspherical lens

ethan hong , Jun 06, 1999; 04:25 a.m.

i've been seeing lots of P&S w. aspherical lenses. can anyone provide more info on this rising phenomena. what's the hype?

Responses

Dave Evans , Jun 06, 1999; 05:29 a.m.

Spherical lenses have surfaces, which are defined by the radius of a given sphere. They are relatively easy to manufacture using equipment, which can generate that consistent curve on the surface of the lens through grinding and polishing.

Aspheric lenses have a surface curve, which is not spherical. They are usually made up of a series of convex and concave curves. These lenses are difficult to make via grinding and polishing. Today most of them are made through a molding process.

One aspheric lens can often take the place of three spherical lenses in a lens design, saving weight and space. They can also be used to reduce certain kinds of distortion.

Charles Miller , Jun 06, 1999; 12:36 p.m.

In my opinion, and merely as a general rule, the term "aspherical" is mostly hype. Expensive lenses with regular elements usually out perform inexpensive aspherical lenses, for instance.

Darron Spohn , Jun 07, 1999; 01:17 a.m.

This is answered in the static content. Click on the Optics link on the main photo.net page. The Ask a Question page sugests "You might also want to browse the static articles in photo.net and/or do a full-text search through the static photo.net articles..."

If you had done this you would have found the answer to your question.

Vadim Makarov , Jun 07, 1999; 10:09 a.m.

Canon's explanation of this technology, used in their wide-angle and ultrafast lenses.

Vadim Makarov , Jun 07, 1999; 10:17 a.m.

Philip G's explanation (look under "Why you might want that fancy zoom P&S")

Nelson Tan , Jun 08, 1999; 06:52 a.m.

Just to add to the info already given:

Most consumer-level lenses have molded aspherical lenses, which are plastic aspherical layered over spherical glass elements. It leads to cheaper production, and approximates the true grounded-glass aspherical elements. But the more expensive lenses (eg. Noct Nikkors) still use the grounded version for more precision. Does anyone know if there is any visible difference in the pictures taken by lenses using the two different techniques?

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