I have find some time to determine the optimal setting for Sigma 8mm F3.5 Canon and Nikon on R1.
Here is a table to show the settings.

I would appreciate if users can test the validity by making a pano using my value(s).
I will make integrated rail plate for selected tilt angles. I will give 10 free copies for responders (one each) of each mount. $10 in value.