This is a test of the 1D Mark II + 550EX flash using the 85mm f/1.8, 50mm f/1.4, 16-35mm f/2.8, and 70-200 f/2.8. The camera was in Manual Mode, f/5.6, T=1/60. The camera CFn14 was tested as 14-0 and 14-1. The ambient lighting was 1.3s at f/5.6. I was very surprised at the consistency of the results. I had gotten results yesterday using the 24-70 in a museum that were all underexposed by 1/2 to 1 stop.