well I have to disagree with you in a very large way on this one, PJF. many programs, most especially mental ray, Renderman, and of course Maxwell deal with light the same way that "real-life" renderers (our eyes, cameras) do. the physics behind photons, radiosity, and the "mechanism" you speak of have been calculated for decades, merely awaiting fast enough PC's to deal with them... the same holds true for ray-tracing algorithms, which were developed by hand in the '70's originally. take a Google at mental ray sometime, or Maxwell, and you'll find that radiosity is indeed just like real light. an object radiating visible light produces radiosity, thus the prefix. you will note that ray-traced "light" doesn't act anything like photons do. as for your disclaimer about what "professional" is and your indifference to it, my point was that for someone to make a profession out of Pro-Render would mean that their lifelong accumulation of final projects (money-projects, that is) would be limited in proportion to it's vastly, vastly slow render-times. so, a V-ray or mental ray user would finish several thousand more projects in their lifetime, and in turn pull in several thousand times the revenue. as a career choice, or a "profession", the math simply doesn't add up for Pro-Render. of course, one could just play it all off as Pro-Render being FOR rendering, such as Pro-choice people are FOR choice or, prohibition is FOR hibition whatever hibition might be!