I'm not an expert on negative light but I recall Bruce had it. Anyway, it removes illumination rather than adds it. Birn showed an example of using it to fake a shadow (so as to speed render time). Say you had a ball. You could light it from the front with a normal light. You could then setup an anti-light that doesn't cast shadows (so it shines through the ball) and also have the anti-light not illimunate (or in this case darken) the ball (apparently some apps allow that?). When I saw it added to Bryce 4 or 5, I didn't really know what to use it for. Birn has a few examples but it still doesn't seem absolutely necessary. Marc (Digital Lighting & Rendering by Jeremy Birn, George Maestri (Editor) )