John

Taking a look at your results, it is no wonder people have trouble doing this with cereal boxes and yard sticks.
I would have a problem just picking what number to use as an average.

Looking at your results with the 5D II and the 70-200mm they are similar to the results that I was seeing with the lensalign. If you were to graph the AF performance in relation to the lens length, initially to me it seems the lens has an elongated S curve the optimum AF point follows. The designers of the lens obviously know this. I wonder what point on the lens did they use to determine what point would be the zero point for optimum AF performance. Say if they use the point where the lens is extended to 145mm it would give the best average for the lens throughout. It would be nice to have this information, maybe if someone were to ask nicely Canon would tell us the best point to establish an AF adjustment point is at XXXmm......probably not....

Rick