ASPH Lens

Hi, Bill -- Each aspheric surface used in a lens potentially can result in one less whole element being necessary, and/or that abberations can be better corrected, especially at wide apertures.

Fewer elements often results in less internal flare, better contrast, and potentially smaller and lighter. But I think most lens makers take advantage of one or more aspheric surfaces to improve performance.

In conjunction with asph surfaces, current designers seem to often use moving elements or groups that shift position in focusing to improve close-up performance and then construct the lens to focus closer.

The better correction of optical abberations seems to have the side effect of making out-of-focus areas somewhat less pleasant. So some avoid asph lenses in pursuit of the 'classical' aesthetic. :)
 
wwulfsohn said:
What is the advantage of getting an ASPH lens? Is it worth the exta money?

Thank you.

Bill

Well, instead of spending the extra money on an ASPH lens, you could dig a hole in your back yard and bury the money in it. But most photographers would feel your priorities were misplaced, and would say, "He doesn't know his ASPH from a hole in the ground."



Sorry, it's late and I couldn't resist. Doug's answer is very comprehensive and seems correct (although I suspect that harsh out-of-focus areas are not an inherent characteristic of aspheric designs, just a byproduct of a lens designer emphasizing sharpness and contrast above all else...)
 
The only way to tell if it is worth the money for you is to actually borrow or rent one and start using it.
On the other hand, if you have to ask this question, it might be a good idea to look at some of the excellent lenses Zeiss and CV offer.
Also, there is Sean Reids highly recommended website (not free) which will answer most, if not all of your questions.

http://www.reidreviews.com/reidreviews/
 
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