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Achromat Lenses


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#1 CJ Henke III

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Posted 11 April 2009 - 04:13 AM

I understand that there a multi-coated and varies degrees to which these are manufactured, but when someone puts Achromat next to a lens does this always mean that it is a "Macro Lens" technically speaking? Or are there different types of Macro lenses.

Are these basically the same lenses? (Forget the obvious difference in Macro Strength and Brand/ Quality)

http://cgi.ebay.com/...ILTER-72mm-NEW-n-


http://cgi.ebay.com/...a...3:1|294:200


Thanks,
Concave - Convex is about all I know about lens shapes.
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#2 Adam Frisch FSF

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Posted 11 April 2009 - 05:13 PM

No, an achromatic lens has no relation to macro. An achromat is two lenses of different refractive glass (normally Crown and Flint glass) sandwiched together to get rid of chromatic aberration. There are five main aberrations in lenses; coma, astigmatism, distortion, chromatic aberration and spherical aberration.
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#3 Richard Sterndale Bennett

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Posted 12 April 2009 - 01:05 PM

Building on what Adam said, there's a fairly thorough Wikipedia article on this stuff if you'd like to learn a little more about it.

http://en.wikipedia....atic_aberration
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#4 Dan Salzmann

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Posted 12 April 2009 - 03:18 PM

No, an achromatic lens has no relation to macro. An achromat is two lenses of different refractive glass (normally Crown and Flint glass) sandwiched together to get rid of chromatic aberration. There are five main aberrations in lenses; coma, astigmatism, distortion, chromatic aberration and spherical aberration.




And when three or more lenses of different refractive glass are used it is an apochromatic lens.
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#5 Chris Keth

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Posted 12 April 2009 - 06:12 PM

Most modern lenses (including macros) will be achromatic and coated, if not apochromatic and multi coated.

Those correction properties and the macro focusing properties are not interrelated in any way. It's not a bad idea to read up on at least basic optics. It will help you to decode the terminology surrounding various types of lenses and their characteristics.
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