Maxwell does not behave like real light. I don't think any commercial renderer behaves like real light. Renderers however do try to act similair to real light. My understanding is that Maxwell fires off a few rays to find out which bits are solid and then guesses the color values of the everything around it before doing a bit more raytracing to find out how good its guess was. That is hardly how real light behaves. If one wants to test the "realism" of Maxwell, one should write a renderer that traces the path of every photon and its interaction with air molecules, dust particles and the surfaces of materials at a molecular level and compare the results (after a few months of rendering at a large supercomputer) with Maxwell. I'm very confident that one will find the results to be different.

OK, what I just said sounds like technobabble from Star Trek, but I hope it does give an idea of how far Maxwell is from simulating real light.


Also, I suspect the reason why mental ray is so slow is becuase it wasn't tweaked. Tweaking is very important.