FFMPEG command differences possible?

[WoutStandaert]

I've just encoded a bunch of H265 10-bit files to ProRes using FFMpeg, so your results have me slightly worried that I'm losing dynamic range.

I used different encoding options though:

ffmpeg -hwaccel cuda -i inputVideo.mp4 -c:v prores_ks -profile:v 3 -vendor apl0 -bits_per_mb 8000 -pix_fmt yuv422p10le proRes422_output.mov

In particular the pix_fmt parameter is supposed to force proper 10-bit output, but probably this parameter is automatically selected, since you are measuring values "higher than 8-bit" anyway. Do you think this would give a different result than your tests?