Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 331

AF Area Selection Modes (Viewfinder Shooting) Spot AF (Manual Selection) 1-Point AF (Manual Selection) AF Point Expansion (Manual Selection ) AF Point Expansion (Manual Selection: Surround) Zone AF (Manual Selection of Zone) Large Zone AF (Manual Selection of Zone) Automatic Selection AF Shooting Conditions That Make Focusing Difficult Caution The camera continues to switch the active AF point < > to track subjects when Automatic selection AF, Large Zone AF, or Zone AF is set to AI Servo AF, but tracking may not be possible under some shooting conditions, such as when subjects are small. Focusing with the AF-assist beam of a Speedlite may be difficult when using Spot AF. Focusing with the AF-assist beam of a Speedlite may be difficult when using a peripheral AF point or a wide-angle or telephoto lens. In such a case, use the center AF point or an AF point close to the center. Wearing polarized sunglasses or similar eyewear may make it difficult to see AF points in the viewfinder. Note With [ : Orientation linked AF point], you can set the AF area selection mode + AF point or only the AF point separately for the horizontal and vertical orientations ( ). With [ : Selectable AF point], you can change the number of AF points available for manual selection ( ). 331