61-Point Af; The Number And Placement Of Cross-Type Points Used By The - Canon EOS-1DX Af Setting Manualbook

61-point AF (4)

The number and placement of
cross-type points used by the f/8
lenses
AF shooting is possible using the center AF
point even with a maximum aperture value of
f/8
When using an extender on the EOS-1D X, AF is possible
using the single center point in the viewfinder even on a
lens with a total maximum aperture of f/8.
This combination of a lens with a maximum aperture
value of f/4 + Ext EF2x and a lens with a main maximum
aperture value of f/5.6 + Ext EF1.4x belongs in group H.
For example, AF focusing is possible even when shooting
with an EF2x extender attached to an EF500mm F4LII
USM with a focal length of 1000mm, making extenders
even more useful.
EF500mm F4L IS II USM
Extender EF 2x III
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