Quoting JC O'Connell <hifis...@gate.net>:
there were two versions of the tamron 90/2.5 macro adaptall lens.
do they both have this problem? (same optical design on the rear element?)
Don't know. Mine is the 52B which, I think, is the early version.
I did a few quick and dirty tests today using the lens on my *istDS
and K200D. Both showed the central 'hot spot' at f16 but it was hard
to pick up at f8. I also tried it with the adaptall 2x adapter and
with a short extension tube.
With the 2x adapter, there may have been a slight hot spot at f16 but
it was barely noticeable.
With the extension tube there didn't seem to be any hot spot at f16.
I've been using the lens on my *istDS for wildflower photography for 5
or 6 years and have never noticed the problem. Looking at a sample of
those images, I couldn't pick up any noticeable hot spot. I'm fairly
sure that in most real world situations, the lens will perform OK, so
I won't be replacing it just yet.
--
Cheers
Brian
++++++++++++++++++++++++++++++++++
Brian Walters
Western Sydney Australia
http://lyons-ryan.org/southernlight/
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