Kibo informs me that "Don" stated that:

Folks

I have been trying to use the Tamron SP AF TeleConvertor 300F-CA 2X with my
400 F5.6 L series lens but the results are dismal. I obviously was aware I
would have to manual focus but I haven't been able to get a sharp shot or
even a keeper for that matter yet. Any one has any ideas or similar
experience or would care to comment and assist me if I am doing something
wrong. I have tried from F11 to F14 on tripod etc.

I also have a 10D, & I've found it impossible to get a good manual focus
in general, due to fuzziness of the & lack of focussing aids on the
viewfinder. I'm guessing that you're running into the same problem.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
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