From: John Sheehy on 16 Feb 2010 17:59
bob(a)myhouse.com wrote in
> here is the ISO 12233 test for this lens, compared to others.
That's pretty bad. That wasn't even within my assumed range of
possibilities. Is this typical for this lens, do you know? CA starts
right near the center, and it is so strong that each color channel is
severely radial-blurred. I don't know if there are any good CA corrections
which work by promoting to more than 3 color channels, as three color
channels are too few, really to correct extreme CA. The 135 f/2 compares
quite favorably at 270mm with a 2x TC.