Canon EOS R5C Manual page 443

Specifying the Range of Images to Convert
1.
Select [Select range].
2.
Specify the range of images.
Select the first image (start point).
Next, select the last image (end point). A checkmark [ ] will be
appended to all the images within the range between first and last
images.
To select other images, repeat step 2.
3.
Press the < > button.
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