The 5D Mk iii can correct aberrations, etc with this function enabled and for lenses that it recognizes. Canon also says that with third party lenses one should disable the function because it may confuse a third party lens with a canon lens and apply the wrong correction. I find that tough to buy, but it begs the following questions:
1. I assume your tests are with this function disabled. If that's true, and I turn it on, for lenses that it recognizes, does it improve the score?
2. After seeing the Sigma prime results, I would like to purchase them, but I'm not happy about turning off the corrections for my Canon lenses. What would you do? Disable the correction?
3. I assume if I use DxO optics Pro (about to buy it), that it would apply the corrections in any event- true?
Thanks, Bob (everything I do is RAW. Have a 1Dx and am about to purchase a 5D Mk iii)