Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 68)

Attaching/Detaching Lenses
Attaching a Lens
Detaching a Lens
All EF lenses can be used. The camera cannot be used with RF, EF-S, or EF-M lenses.
Caution
Do not look at the sun directly through any lens. Doing so may cause loss of vision.
When attaching or detaching a lens, set the camera's power switch to <
>.
If the front part (focusing ring) of the lens rotates during autofocusing, do not touch
the rotating part.
Tips for avoiding smudges and dust
When changing lenses, do it quickly in a place with minimal dust.
When storing the camera without a lens attached, be sure to attach the body cap to
the camera.
Remove smudges and dust on the body cap before attaching it.
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