Disappointingly, it didn't work for me. My 300mm f/2.8 is +8 on FoCal and sloping ruler tests, but +2 on the Dot. With a 2xTC, it is +6 on FoCal and slope and -8 on the dot. For the latter, the actual image at +6 was the same quality as live view and -8 out of focus.
The method did work spot on for the 100-400mm L. The series II telephotos do have sophisticated focussing algorithms and perhaps they don't work so well with the manual focussing dot. It is surprising that the green dot lights up over a range of 20 units.
« Last Edit: February 14, 2013, 06:36:25 PM by AlanF »
5DS R, 7D II, EOS-M, Powershot G3 X, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M 18-55, f/2 22, 11-22