Originally posted by Frogfish Again very interesting - thanks dgaies. More food for thought !
At present I'm using the Tamron BB 500mm Mirror for my long range shooting (manual focus of course) so having to do that with the AFA doesn't bother me at all since it locks in really fast once you're in the ballpark. My experiences with the Tamron 1.4x on other lenses are identical to yours - it seems to work well with everything - however it does focus hunt a lot.
Without getting too far off topic (as this thread is about the 60-250), I will say that the Tamron 1.4x works very well with the Tamron 70-200 in terms of IQ. Focus still hunts a bit depending on the situation, but overall they work better together than the 1.4x does with the DA* lenses.