Canon EOS-1DX Af Setting Manualbook page 47

Tip for AF setting
Change the level of "Accelerate /
decelerate Tracking" and "AF point auto
switching" for the appropriate for
shooting result.
"Accelerate / decelerate Tracking" and "AF point
auto switching" are part of the Camera's automatic
functions. Therefore it is not always possible that
these automatic functions reflect 100% of your
intended idea. If you feel unhappy with shooting
result, try to change the effect level of their
functions.
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