Canon EOS-1D X Mark III Advanced User's Manual page 950

Multiple exposures
Shooting method
Number of multiple exposures
Multiple-exposure control
HDR shooting (still photo HDR PQ)
Recording format
Bit depth
Color sampling
HDR specification
Shutter
Type
Shutter mode
Shutter speed
Function/control priority, Continuous shooting priority
2 to 9 exposures
Additive, Average, Bright, Dark
HEIF
10-bit
YCbCr 4:2:2
ITU-R BT.2100 (PQ)
Electronically controlled, focal-plane shutter
Viewfinder shooting: Mechanical
Live View shooting: Mechanical, Electronic 1st-curtain, Electronic
Mechanical/Electronic 1st-curtain set: 1/8000 sec. to 30 sec., Bulb
Electronic set: 1/8000 sec. to 0.5 sec.
Max. shutter speed with flash sync: 1/250 sec.
* Setting range differs when recording movies
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