Canon MARK IV User Manual (en)

 Shooting Movies
You can take a still photo at anytime by 
pressing the shutter button completely, 
even during movie shooting.
The still photo will record the entire screen including the semi-
transparent mask.
The still photo will be taken at the exposure setting displayed when 
you press the shutter button halfway. If a still photo is shot during 
movie shooting in manual exposure mode, the still photo will be 
taken with the exposure setting set for the movie.
The still photo will be taken at the image size, JPEG compression 
rate, and Picture Style that have been set.
If you take a still photo during movie shooting, the movie will have a 
still moment lasting approx. 1 sec. The still photo will be recorded to 
the card, and the movie shooting will resume automatically when the 
Live View image is displayed.
The movie and still photo will be recorded to the card as separate 
files. If you use continuous shooting, the captured still photos will be 
recorded to the card.
If [Record func.] (p.57) is set to [Standard] or [Auto switch media], 
the movies and still photos will be recorded to the same card. If 
[Rec. separately] or [Rec. to multiple] is set, the movies will be 
recorded to the card set for [Playback]. And the still photos will be 
recorded at the image size set for the respective card.
Taking Still Photos During Movie Shooting
Any external Speedlite used will not fire.
AEB cannot be used.
Continuous still photo shooting is possible during movie shooting, but the 
captured images will not be displayed during the continuous shooting. 
Depending on the still photo’s image size, number of shots during 
continuous shooting, card performance, etc., the movie shooting might 
stop automatically.