Canon EOS-1DX MARK II Settings Manual page 97

2
Parameters during continuous shooting
[AI Servo 2nd image priority]
Equal priority
For 2nd and subsequent shots in a continuous sequence, this
setting gives equal priority to both focus and shooting speed.
The FPS rate of continuous shooting may slow down when it is
dark, or in low contrast.
Shooting speed priority
This setting gives priority to continuous shooting speed over
focus. Continuous shooting speed will not drop. Effective when
you want to shoot with an approximate fixed interval between
photos. A setting of [ - 2] will maintain continuous shooting
speed.
Focus priority
This setting gives priority to focusing over continuous shooting
speed. It will not shoot a picture unless it is in focus. It is
recommended when you want to shoot only after focusing on
the subject. This setting makes the most of AF low-light
performance with AI Servo AF, but when [ + 2] is selected the
continuous shooting rate will be reduced.
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