[Klaus]

Well, in a fair comparison you would have to crop the results of the 100-400L and then interpolate the image size back to the same resolution. I have some doubts there. However, the 100-400L + 1.4x may be an option that is worth to consider though. The 5Ds can AF till f/8 for instance. 

 

That all being said I doubt that the Tammy is the best fish in the pool. As mentioned in the review I am considering this to be a budget lens (in this class). The Sigma 150-600 Sports is next ...