I am slightly annoyed with Bryce 5 because it takes so much longer to render. An image that took 5 hours to render in 4 would be approximately double that in ver 5. I would advise to stay away from volumetrics unless you can afford to leave your p.c. sit and render for a few hours-days. World Builder seems to be more powerfull and is a lot faster in render times....if you are serious about imagery.