A reader noticed that “the hot-shoe on the Leica S2 appears to be a Nikon pin-out configuration – Leica’s usual M-TTL hot-shoe has longer contacts towards the back of the body.”
Here is a comparison (Leica S2 vs Nikon D700):
A reader noticed that “the hot-shoe on the Leica S2 appears to be a Nikon pin-out configuration – Leica’s usual M-TTL hot-shoe has longer contacts towards the back of the body.”