Thanks, I will check the Shoestring Shaders out. I'm new to Carrara, until now I just played with the Carvers Guild plug-ins. Basically that's for those plug-ins I wanted to do this project in Carrara, otherwise I could have that negative light in Poser, Vue or C4D. In fact I wanted to project a black light ray into the scene, darkening everything where it falls just like a real light ray would lighten them. Of course I can trick it a hundred different ways, probably including a invisible "ray object" and a proximity shader or just render with a real light ray and substract the result from the normal render in Photoshop ... I just wanted to do it in the clean way :)