Hello Ken
Welcome back.
I'm really struggling with auto focusing when I use Nikon D810A.
The autofocusing works great with QSI683 but somehow it is not working well with D810A.
I'm not sure this is due to thee new aggressive binning done to accommodate slower PCs.
During autofocusing the image statistics report binning 800.
Another thing that I notice is that the number of stars found reduces a lot while the autofocus routine approaches to the best focus.
For example the number of stars are 300 when HFD is 4.5 but it starts reducing.
When the HFD is around 3.2, the number of stars are reduced down to below 70 near the best focus.
This seems to be skewing HFD by not using those smallest well focused stars.
I tried different minimum pixel sizes but it didn't really help me.
I'm not sure if my issue is the resolution of the images or the nature of DSLR images.
Thank you.
Donghun