Thanks Neuro! I appreciate the detail of the answer. I just learned a lot about how my camera works (BTW - Where would one go to find such detailed information about camera firmware?). I have seen a couple of reviews of the 70D with the Sigma 18-35 1.8 and it performed nicely with the DPAF. Obviously the new Sigma would use a newer Canon LensID so I imagine that is why it is performing well.