I create a simple scene with overlying spheres. Each sphere has #000000 transparent material mixed with grey diffuse. No matter how I set factor on mix shader (even if it should be completely transparent), there are pitch black “things” in places, where spheres are overlapping. Why is that?
Blender 2.71, cycles GPU. Effect persists no matter how I change light, bounces etc.
untitled.blend (497 KB)