So, per the DP review description,
"The 5D Mark III loses out to the Nikon D4 and D800 when it comes to use with slower lenses or long lens/teleconverter combinations, in that its cross-type points can only be used with lenses that are F4 or brighter (and the double-crosses with F2.8 and brighter lenses)
. Canon says there's a trade-off to be made and that its approach allows the sensor to be more accurate with the large aperture lenses it expects its customers to use, and allows the F4 cross-type sensors to be placed further towards the edge of the frame."
So, the middle AF point (and indeed much of the center column) is double cross type. All points in the center three columns are either cross or double-cross points.
Does that mean that, if I'm using an f/5.6 lens (say 100-400 at max focal length), I would only be able to use points from columns 1, 4, 8 and 11? Or will the higher accuracy points function with less fidelity? Can I not use the center point with my 25-105?
Seems kinda foolish to force focus off center for slower lenses.