Canon EOS 5D Mark III Instruction Manual page 183

FAQ
Are there any restrictions on the image-recording quality?

All JPEG image-recording quality settings can be selected. If 41 or
61 is set, the merged multiple-exposure will be a 1 image.
Image-Recording
Quality Setting
JPEG
1
41/61
1+JPEG
41/61+JPEG
Can I merge images recorded in the card?

With [Select image for multi. expo.], you can select the first single
exposure from the images recorded on the card (p.181). Note that you
cannot merge multiple images already recorded on the card.
Are multiple exposures possible with Live View shooting?

With [On:Func/Ctrl] set, you can shoot multiple exposures with Live
View shooting (p.197). Note that [z4: Aspect ratio] will be fixed at [3:2].
What file numbers are used for saving merged multiple-

exposures?
If all images are set to be saved, the merged multiple-exposure image file
number will be the serial number coming after the file number of the final
single exposure used to create the merged multiple-exposure image.
Will auto power off take effect during multiple-exposure

shooting?
As long as [52: Auto power off] is not set to [Disable], the power will
turn off automatically after 30 min. of non-operation. If the auto power off
takes effect, multiple-exposure shooting will end, and multiple-exposure
settings will be canceled. Before starting the multiple-exposure shooting,
the auto power off will take effect as set with the camera, and multiple-
exposure settings will be canceled.
Single Exposures
JPEG
1
41/61
1+JPEG
41/61+JPEG
P Multiple ExposuresN
Merged Multiple-
Exposure
JPEG
1
1
1+JPEG
1+JPEG
183