Currently I have a 7D, but, with the 100-400 it will not autofocus with the 1.4x.
By my calculation- max reach is 640mm.
I also have the 5D2 which is starting to annoy me with so very few focussing points.
I am thinking of selling it and getting a used 1D series which will autofocus the 100-400 with the 1.4x. Working out- max reach I would get 728mm
Would I see the difference between 640 and 728? Am assuming I can crop more heavily with the 1D's
mainly for wildlife
or shall I not bother!