I assume the lower rail measurement is read via the inner edge of the upper rail base? I fine tuned it a bit more and am now at 57. Haven't followed the steps in the easypano link yet, but the bullseye mark on the top of the NN rotator is centered in camera viewport exactly if I rotate it around. Used this setting along with 92 for upper rail with the Samyang (Rokinon brand) for a pano shoot on Sunday and stitching in Hugin worked great. No seams or obvious parallax errors.