Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 509)

509
Troubleshooting Guide
Regarding the AF points lighting up or blinking when you press the
<
S > button, see page 95.
The registered AF point at its position is blinking (p.95, 450).
The manually-selected AF point (or zone) and the registered AF point
are displayed (p.94, 450).
Set the AF operation to One-Shot AF (p.88). Note that focus lock will
not work in the AI Servo AF mode (p.89).
The continuous shooting speed for high-speed continuous shooting
may become slower depending on the power source type, battery
level, temperature, ISO speed, flicker reduction, shutter speed,
aperture, subject conditions, brightness, lens, flash use, and shooting
function settings. For details, see pages 148, 149.
If you shoot something that has fine detail such as a field of grass, the
file size will be larger, and the actual maximum burst may be lower
than the number listed on page 158.
If [ Rec. separately ] is set and different image sizes are set for the CF
card (Card1) and CFast card (Card2), the maximum burst for
continuous shooting will decrease.
The AF point is blinking or two AF points are displayed.
I cannot lock the focus and recompose the shot.
The continuous shooting speed is slow.
The maximum burst during continuous shooting is lower.