i'll just chime in real quick with a stills guy perspective, some of our lighting rigs sole purpose is to hide the hot spot of the actual lamp in order to avoid sharpness of shadows, for instance the octabank (literally an octagonal light about 6ft in diameter) in which the head is rigged facing away from the subject bouncing into a silver umbrella type affair and then running out through a full diffusion silk creating a very even spread across the diameter of the light. another example is the beauty dish, a much smaller light source about 20in in diameter has the head hidden behind a small disc in the centre which bounces light back into the dish which can be silver or white depending on the sharpness of shadow required. these both achieve a very even shadow termination i.e highlight to shadow is a smooth transition, then the distance to source determines the rest as already mentioned. g