Just wanted to add a comment on the method that might be useful for 1D MkIII owners. Firstly, I found this approach very useful - so my thanks go to the OP who posted the link and also to the original author - Arash.
Now, the methodology applies to EOS bodies that allow Quick AF within Live View. 1DIII has LV but no AF in LV. Though when using EOS Utility in a tethered set up, microadjust steps are still available. So if you want to MA your 1DIII, all you need to do is to connect the camera to EOS Utility, perform AF using shutter or back button (or remote cable), then bring up LV in 200% view and perform MA steps. It worked well for me.
Now my observations using this method to MA for my 50L:
- I needed -8 on both 1DIII and 1DIV (previously I had set it at -11 on 1DIII and -8 on 1DIV)
- I needed -4 on my 5DII (previously set at -6)
- I needed 0 on my 7D (previously -2)
I checked the MA at 20X (1 m) and 40X (2 m) of focal length using f/2.2 to find the best balanced MA.
Not needing MA with 7D now means I need to check a couple of other lenses with it to make sure it doesn't front focus.