Hey Javier,
I just received a Tamron MC7 TC but still haven't given it a good test. I recall you saying you have a Tamron 2x TC but don't remember which one. Is it the MC4 or MC7? I remember you saying yours left your images flat. I'm going to try to get out today if we get some sun here in Seattle and test in good light. Will let you know the outcome.

BTW, thanks again for directing me to the Sigma 100-300 f/4. I love it! Great versitility and IQ and cann't beat the price.

Peace,
Oren