Canon EOS 1Ds Mark III Instruction Manual page 74

Selecting the Media, Folder, and Recording Method
3 Setting the Recording Method
You can set how the image is recorded to the memory card.
Standard
When both memory cards are in the camera, the selected card will
record the images.
Auto switch media
When both memory cards are in the camera, the selected card will
record the images. Then when the card becomes full, the camera
will automatically switch to the other card to record images.
Rec. separately
Each image is recorded to both the CF and SD cards. The image
size (3/4/5/6/1/9) to be recorded can be set individually
for each card. (p.52) For example, you can record a JPEG image to
both cards or a RAW image to one card and sRAW to the other card.
Rec. to multiple
Each image is recorded to both the CF and SD cards
simultaneously. 1+JPEG or 9+JPEG can also be selected.
(p.52)
74
Select [Record func+media/folder
1
sel.].
Under the [5] tab, select [Record
func+media/folder sel.], then press
<0>.
Select [Record func.].
2
Turn the <5> dial to select [Record
func.], then press <0>.
Select the recording method.
3
Turn the <5> dial to select the
recording method, then press <0>.