Justin Hunt

There are some basic concepts to be understood with photons

1) Photons are multi bounce, this is controled by the max trace depth in the photon settings. This number is the number of bounces, I usually use 30

2) FG is 0 bounce, if you set it higher, they are still calculated but then disregared at rendertime, open the message window and it will tell you as much. So leave FG at 0. The density, number of samples and intoplate are still relevant

3) Be sure to check the light photon settings, these will give you control for individual lights. Just switch between Automatic (which use the render setting numbers) and Maual, where you specify energy, number of photons and decay.

4) The physical scale in the exposure control panel is important as this sets the energy scale for the lights.

Overall Phons with FG is very quick. It does give different results than FG only rendering, Such as more colour variation in shadows. It may take a little time to get just the right numbers but its worth it in the end.

As to the darkening/more contrast. This is correct as with the more photons being shot, the more accurate the lighting solution will be. Another effect is more saturated colours

jhv