Well the reel takes 5 meters, but the canister takes 3.6-5.2 meters depending on the base of the film.
So I just load till its full, I have specific 15 feet "bulk rolls" that I have to re-roll as they don't fit in the cans (must go to another kind of 70mm back) but there's always a little extra than 15 feet (4.6m) so I just shoot it all, most I've gotten was 64 shots.
Once the film came out of the spiral and wrapped around once more, but the emulsion faces inward so it didn't scratch the film and developed just fine. I wonder if the new spool takes less than 5 meters, I think it's the same just that the space between is tighter... We will find out soon.
~Stone
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk