So I see mentioned that only some af points work at smaller apertures.
Secondly: how do I know if a point isn't working, when it behaves as though it does, ie; it locks on and beeps.
Is this why so many of my f8 bird shots are not sharp?
I find it too hard to manually focus an AF lens without live view, as the plane of focus is so narrow (if the bird takes up a good portion of the frame at 600mm), with live view I often miss the shot as the birds move in and out of focus contantly on the branch (the D4 looks as though it locks on MUCH fater in live view, which is great).
It would be handy to have the MF 600mm 5.6. it's small, easier to manually focus and a stop brighter than my 300 2.8 with tc-20eiii (stopped down to f8), but I don't, so help would be appreciated.