According to the Efke pub, the 820c is equivalent to the old Maco 820c film, which I loaded very successfully many times in very subdued light in my Leica Ms. (although I always loaded Kodak HIE by feel in a changing bag). It has an anti-halation backing, so it's thicker and stickier. This may make it a special case for the IIIf as far as your normal leader trimming and spindle attachment routine is concerned -- at least something to think about. Good luck.