I was skeptical at first ..
I wanted the 70-200 f2.8 exchange for my Canon f4 because my maximum aperture of F4 was not sufficient.
At first a little disappointed because the Tamron at open aperture something was very soft but happy now.
One has as already wrote a get to know the objective to deal with it.
Now after a few days I wish to never give up photo there, it is not as crisp sharp as the Canon but the 2.8er open aperture can be easily more leeway and you get images that could not be realized with the Canon so can.
Therefore my conclusion.
Who knack sharpness in fine weather will takes f4 to Canon.
Those looking for an all-rounder, with which you can take pictures "lightweight" sports, animals and portraits even in bad light reaches for Tamron.
And who has the wherewithal, looking to crack sharpness in any situation is operated 2.8er well with the Canon.
I am satisfied with the Tamron and can highly recommend for this price too!