Canon MARK IV User Manual (en)

The camera can use a CF card and SD card. Images can be recorded 
when at least one card is installed in the camera.
If both card slots have a card, you can select which card to record 
images with or record the same images simultaneously on both cards 
(p.56, 57).
If you use an SD card, be sure the card’s write protect switch 
is set upward to enable writing/erasing.
Open the cover.
Flip out and turn the cover release 
handle as shown by the arrow.
Insert the card.
The left slot is for a CF card, and the 
right slot is for an SD card.
As shown in the illustration, face 
the CF card’s label side toward you 
and insert the end with the small 
holes into the camera.
If the card is inserted in the wrong 
way, it may damage the camera.
The CF card eject button will stick 
With the SD card’s label facing you, 
push in the card until it clicks in place.
Close the cover.
Press the cover until it snaps shut.
Installing and Removing the Card
Installing the Card
Write protect switch