If you have a Sony camera and you’re in the market for a 70-200mm F/2.8 lens, check out this comp. Right now, I’m comparing the Sony and Tamron models, but plan to add the two Sigma’s (HSM and HSM OS) when I get them done, hopefully next month.
Optically, the results show a toss-up in my opinion. The Tamron can definitely hold its own against the Sony, and even slightly exceed the Sony in off-center performance if you look closely. If focusing speed and build quality are important, the Sony is the clear winner.