Ghostship is correct. 2nd_World you have a slight misconception happening. "Light Emitter" is indeed for light bounces not self illumination. It allows an object to diffuse incoming light back into the scene when Firefly rendering with indirect light. It is not about glowing objects. It is about light bounces and ambient light. The "light Emitter" option is to ensure the object is participating in IDL calculations. When you untick the option, you are removing IDL bounces form the object you are rendering. That is why your non light emitting parts render like that when you remove the option for IDL bounces. The Light Emitter box. Your plane is not part of the bounced light calculations. Just the initial light calculation and nothing more. Nothing to do with mesh lighting like your spheres above would seem to mistakenly surmise. Essentially, this is not Superfly problem that needs fixing, just a slight mistake as to the meaning of the option.