Success! Thanks for the tips guys! I have ran a half dozen tests with various settings and the one that seems best is with Interpolation off and lighting quality set to Best, with lighting accuracy at 2 pixels. This gives a lovely result on my test piece. I seems that it renders much more quickly with Interpolation off, way faster. Anybody know what interpolation does and when it might be necessary to use it? Thanks for the help, Brian. By the way, I am a Rhino man for ever but I'm going to be using C4pro a lot as it now imports Rhino nurbs directly. Happy days ahead.

Brian

Fortitudine Vincimus - "by endurance we conquer."