<< I didn't mean to imply you should not
I think I sounded a bit too testy about the tests. Fred from FM does a similar
analysis all the time and Roger thinks highly of him even if Roger only rarely
subjects a lens he has purchased to his 250K optical bench.
"Decentering" is rather broad and might mean a lens element or group are
slightly off axis, tilted or even bad spacing. Field curvature that may be
asymmetric especially in zooms can play a role and swapping lenses probably is
trading different defects. For this particular purpose of astro wide open lens
use with possible printing in mind, it is worth the modest effort to do some
tests, IMO. An obvious soft corner was not acceptable. Stopped down for a
landscape, one would never know.
Roger C from Lensrentals, Lord of the Lens, stated
"Fred is the most meticulous on-camera tester I know. Personally, I wouldn't
spend the time it takes him to do his tests, but I guarantee you he knows every
one of his lenses completely."
Almost done testing, but need clear skies, Mike
Themed Olympus Photo Exhibition: http://www.tope.nl/