Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 514)

Troubleshooting Guide
514
ISO speed will be set according to the setting of [ Range for stills ] for
[ z 2:ISO speed settings ] (p.166) during viewfinder shooting and Live
View shooting, or the setting of [ Range for movies ] and [ Range for
H ] (p.330) during movie shooting.
If you change the shutter speed or aperture during movie shooting, the
changes in the exposure may be recorded.
Shooting a few test movies is recommended if you intend to perform
zooming during movie shooting. Zooming during movie shooting may
result in recoding images with changes in exposure or operation
sound, or images may be out of focus.
Flickering, horizontal stripes (noise), or irregular exposures can be
caused by fluorescent lighting, LED lighting, or other light sources
during movie shooting. Also, changes in the exposure (brightness) or
color tone may be recorded. In the <
s > or < a > mode, a slow
shutter speed may reduce the problem.
If you move the camera to the left or right (panning) or shoot a moving
subject, the image may look distorted.
High Frame Rate movies do not record sound.
The manually set ISO speed changes when
switching to movie shooting.
The exposure changes during movie shooting.
The image flickers or horizontal stripes
appear during movie shooting.
The subject looks distorted during movie shooting.
The movie does not record the sound.