Hello. For those who asked, here's what I did.
I tested several lenses for wide-open sharpness/lack of distortion
using a star field as the test subject. The star field for most tests
contained the very bright object, Jupiter, as well as more modest
magnitude stars.
Results: (Blank is did not test) All lenses MC unless noted.
Wide Open One stop down
21/2 - Some Coma Good
21/3.5-(SC) Slight Coma
28/2 - Slight Coma and
very slight blue fringing Good
35/2 - Some Coma Good
50/1.2 - Coma
50/1.4 - Coma,slight blue fringe Good
50/2 macro - Good
85/2 - (SC) Some blue fringing
90/2 macro - Good.
100/2 - Slight coma
The 50/2 and 90/2 were the only lenses that proved sharp and
distortion-free when used wide open.The 50/2 macro wide open was
slightly better than the 50/1.4 at F/2. The distortive effects were gone
for all practical purposes on all lenses when closed down one stop.
The 21/3.5 was much better than the 21/2 wide open. However, the 21/2
at F/2.8 was better that the 21/3.5 at F/3.5.
The worst coma was exhibited by the 50/1.2 and 50/1.4
The blue fringing, of course, is chromatic aberation. I was less
surprised to see it on the SC 85/2 than on the MC 28/2.
The coma was seen mainly on the very bright objects - Jupiter and a
bright star of magnitude 1 or so. Lesser magnitude objects showed no
visible coma (thru an 8x loupe.)
That's it. Hope this is useful. .
take care
george
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