I recently rented the A7 from LensRentals to gage whether it had all the requirements to replace my A850. Well, I was pleasantly surprised with the autofocus using the 35 f2.8. Even in low light I would describe it as reasonably good. However recently I have seen a number of descriptions stating that the A7R actually has more accurate low light AF than the A7. If that were the case I would probably prefer the A7R. If anyone has personally had both cameras in hand and tested the autofocus with the native lenses and has an opinion on low light capability I'd love to hear about it before putting in my order.