jrista said:
he major difference with the A7s is the massive increase to SNR...it's about double or so compared to even the vaunted 1D X, on top of the huge DR increase (6.6 stops 1D X, 8.8 stops A7s, at ISO 51200). THAT is HUGE for high ISO IQ. Massively huge. It means a literal one-stop or greater improvement in noise, which I didn't even think was possible (and I still don't know how they did it....other than the fact that their sensor just seems to suck up light like it was candy.)
To be fair, the 6D scores, using NORMALIZED

;D results (I will give you that you are not a fanboy though as you stick to no normalization for DR whether it makes any particular brand look better or worse, but I think if you looked at normalized results you might be a touch less puzzled over how they pulled it off, because, IMO, SONY didn't really pull off something to the degree you think they did in this case) gives 6.93 at ISO51,200 and Sony A7S gives 8.19 so the difference is 1.26 stops not 2.2 stops (which, maybe you'll agree is an improvement that is easier to fathom, it's still a nice improvement though, 1.26 stops is hardly nothing and compared to the 5D3 we are talking 6.29 vs 8.19 or 1.9 stops, a pretty decent bit more. So it has like 2 stops better DR at very high ISO and about the same at low ISO (it actually fairs a bit poorly compared to other Exmor sensors for low ISO DR though). It's large pixels make the grain larger than the 6D or 5D3 though.
Also, I think you accidentally used the 21,560 info instead of 51,200?? Not that it matters.