Canon EOS-1DX Instruction Manual page 95

-2/-1: Shooting speed priority
Priority is given to the continuous shooting speed instead of achieving
focus. With -2, decrease of continuous shooting speed can be better
prevented than with -1.
+1/+2: Focus priority
Priority is given to achieving focus instead of the continuous shooting
speed. The picture is not taken until focus is achieved. Although focus
can be achieved easier in low-light conditions with +2 than with +1,
continuous shooting speed may decrease.
If focus cannot be achieved in low-light conditions when [0: Equal priority]
is set, setting [Focus priority] to [+1] or [+2] may give better results.
23: One Shot
USM lens electronic MF
You can set whether and how to use the electronic focusing ring when
using one of the electronic focusing ring-equipped lenses below.
EF50mm f/1.0L USM
EF85mm f/1.2L USM
EF85mm f/1.2L II USM
EF200mm f/1.8L USM
OFF: Disable in AF mode
When the lens' focus mode switch is set to [AF], manual focusing is
disabled.
EF300mm f/2.8L USM
EF400mm f/2.8L USM
EF400mm f/2.8L II USM EF28-80mm f/2.8-4L USM
EF500mm f/4.5L USM
: Enable after One-Shot AF
If you keep pressing the shutter button
halfway after AF operation, you can
focus manually.
: Disable after One-Shot AF
Manual focusing is disabled after AF
operation.
3 Customizing AF Functions
EF600mm f/4L USM
EF1200mm f/5.6L USM
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