1) Does an illusionary light produce actual radiance, allowing one to see inside a darkened room? Or, is the radiance illusionary, and the things seen within the light radius an illusion too?
2) Can a person use illusion to turn themselves invisible? What happens, then, if you turn a door or wall invisible to look through and see what is on the other side? Is what you see real, or just an illusion?
3) If you create a telescope or periscope with illusion, can you see distant things as if they were closer? Can you look over a wall with the periscope to see what is on the other side?