***FINAL GATHERING ***

Im still a newbie, but if you use mentalray when doing ONLY FG, you would (best i think) want to push the accuracy to over 1000 (1000-4000).

-With min-radius equal to a tenth of the max-radius;
If you dont get the results you like, try these settings;
Min-radius = 0.01
Max-radius = 0.1

or even better

Min-radius = 0.01 (or 0.001)
Max-radius = 0.01

-If radius is set too low, it produces a "low-quality-jpeg" pic, i think. (correct me if I am wrong)



***GLOBAL ILLUMINATION***

-For production results with GI ALONE, i usually push accuracy to max (usually 30000, on my machine).

-Radius can be set automaticly by setting it to 0.
-Raduis is relative to scene size i think.
-Else try to testrender, and start off with small radiuses, AND exposure to 1 (not 2 like in "realistic exposure")
-The exposure = 1 lets you see more clearly the size of the area lit by the individual photon.
-If you increase the number of photons in a shoot, i guess the radius can be smaller, contra a scene with fewer photons.


***GI FG COMBO***
I have tried this once but i do not render much these days. And I am NO expert in mentalray (hard to find anything useful on the net, unless you code you shaders yourself i feel).

-With limited processor power/time, I think I will explore the combo solution sometime in the future. Meaning a "medium" FG WITH a "medium" GI, a little of the both.

-Still FG radius would have to be set good, i think.

-GI accuracy setting can be lowered good, but not the radius, i think.

and...

-FG accuracy setting can be lowered good, but not the radius, i think.

I think this would produce decent renderings in shorter time. But let me know if you want to add anything, as I am puzzled by mentalray settings myself.