D'après mes rechercher sur le net, l'information doit être fournie par l'objectif :
This is the answer I got from Canon Support:

"The EOS 7D does record subject distance to be used in comination with the external flash. However, it does this only when the lens supports reporting the focusing distance.

All lenses introduced before 2004 do not have this capability, and for newer lenses,only the professional and more high-end lenses do have this function. The EFS 18-55 does not have it, because it is not a professional or high end lens. The EFS 17-55 does have it, but the 100-400mm does not because it was introduced before 2004."
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Pour l'avoir dans LR, il faut sélectionner "All" comme indiqué ci-dessous :
In LR, it should show up underneath the "Lens" tag as "Subject Distance" if you have "All" selected to display in the Metadata tab. If you use a lens that has it, like the 85mm f/1.8, there should be a value listed.
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