I tried to AFMA the 1.4xTC III on my 100-400 with my 5DIII using FoCal, and the software gave up! I consider anything under 600mm on the 5DIII as not long enough. As my 5DIII is going in for repair, I have used for the past few days the old 7D for bird photography. Its noise has virtually been eliminated at 640-1250 ISO using DxO PRIME. It's slow but miraculous. The noise just goes away with no perceptible loss of resolution of details of bird plumage.