Quote:
Originally Posted by troypiggo
What's the purpose of the external aperture? Controls diffraction spikes maybe?
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In my case (Canon 200mm FD) it was both chromatic aberration and spikes.. Same lens, internal iris f5.6 and external aperture f5.6.
The difference was drastic.
see here:
http://www.iceinspace.com.au/forum/a...se.php?a=66128