Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 520)

Troubleshooting Guide
520
Depending on your card reader and computer OS, large-capacity CF
cards and CFast cards may not be properly recognized. In such a
case, connect your camera to the computer with the interface cable,
then transfer the images to the computer using EOS Utility (EOS
software, p.552).
41 and 61 images cannot be processed with the camera. Use
Digital Photo Professional (EOS software, p.552) to process those
images.
With this camera, you cannot resize JPEG 6 images or 1 / 41 /
61 images, or frame-grab images from 4K movies saved as still
photos (p.399).
1 / 41 / 61 images and frame-grab images from 4K movies
saved as still photos cannot be cropped with the camera (p.401).
White, red, blue, or other colored dots of light may appear on images if
the sensor has been affected by cosmic rays, etc. Their appearance
may be surpressed if you perform [
Clean now f ] under [ 5 3:
Sensor cleaning ] (p.404).
My card reader does not recognize the card.
I cannot process the RAW image.
I cannot resize or crop the image.
Dots of light appear on the image.