Well this is kind of a letdown for me. I have one on order and I will see what I think of it when it comes but this comparison says its not any better than what I have at 400 and not what I want at 600. It still looks to be good for what its supposed to do but here's a flash bulletin, it's not a substitute for the 600ii, dang!
I can't tell if you were being sarcastic. Was anybody really thinking it would be a substitute for the 600 II? It's 1/12th the price. Anyway, other tests show significant sharpness gains if you stop down at 600mm, and by f/11 its just as good as at 400mm.
I know it seems to be a remarkable product for the price but I was hoping it would be better wide open at 600. My present 600mm option is the sigma 120-300 plus 2xiii which has adequate sharpness but the AF won't keep up with bif. I hope ths one can, if not it still seems to be a good travel and hiking long zoom.
Ya if you have the 120-300 2.8 that makes things tricky. I think that lens (+ext) vs. this Tamron is the big question for those looking to get into the super-tele range on a budget.
When the new lens comes I will do a comparison and post for anyone that is interested.