Canon EOS-1DX Af Setting Manualbook page 88

Improvement of AF performance in low light
with AI servo is possible through new
parameter settings
One of the major changes to the new firmware V2.0 is
improved low-light limit performance. Low-light
performance for the first frame of continuous shooting
AI Servo AF (and while holding down the shutter button
halfway) are improved through a updated algorithm.
This is especially effective when shooting individual shots
using AI Servo AF. AF precision is improved for dark
subjects in low-light situations. The new [+2] parameter
added to [AI Servo 2nd image priority] is maximized
during continuous shooting with a focus on low-light
performance. Because focusing takes priority, continuous
shooting speed drops.
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