Quote Originally Posted by Sean Setters View Post
AF acquisition and accuracy is also something to consider between the two lenses. The Tamron produces good image quality at 400mm, but if it can't lock on to a target in time, then the EF 100-400mm L IS II may prove worthy of its price premium over the budget-friendly Tamron.
This is true. AF will rule supreme over IQ in many cases.

Looking at the charts I have decided the 100-400mm is not a lens I will want to own, at least yet anyway. I am selling my 300mm f/2.8L and will need something in that range.