I'm intrigued by this remark regarding the fudging of results through f-stop variation (f9 vs f5.6 ), so I did some shots myself at ISO12800 (JPEG).
Certainly not defending DPR (which I don't trust at all), but I really want too see how bad the selection of f-stop can be.
Camera was mounted on a tripod.
Lens is a A50/1.4 with hood on. (Sorry don't have a FA50/1.4)
Focusing was MF using LV at x8 mag.
NR OFF
f5.6
f9
I can't fault the use of f9, though I do find fault with the sharpness reported on DPR.
Of course the results can be affected by may things like a lack of hood and poor focus, so we will never be sure.
Repeat : I certainly think I see better than what DPR has put up.