Canon EOS R6 Mark II Mirrorless Camera with 24-105mm f/4-7.1 Lens - Manual (Page 381)

Cards That Can Record Movies
See Card performance requirements (movie recording) for details on cards that can record
at each movie recording size.
Test cards by recording a few movies to make sure they can record correctly at your
specified size (
).
Caution
Before recording 4K movies, format cards by selecting [ Low level format ] in [ :
Format card ] ( ).
FAT32-formatted cards cannot be used when recording movies with a frame rate of
179.8/150 fps.
If you use a slow-writing card when recording movies, the movie may not be
recorded properly. Also, if you play back a movie on a card with a slow reading
speed, the movie may not be played back properly.
When recording movies, use high-performance cards with a writing speed
sufficiently higher than the bit rate.
When movies cannot be recorded properly, format the card and try again. If
formatting the card does not resolve the problem, refer to the card manufacturer's
website, etc.
Note
To obtain better performance with the card, formatting the card with the camera
before recording movies is recommended (
).
To check the card's writing/reading speed, refer to the card manufacturer's website,
etc.
381