In another topic here Dale B wrote about a book by Jeremy Birn. He's a technical lighting director at Pixar: "Probably the first, and classic cheat he shows in passing is the table lamp and shade. Lots of newbies get frustrated with this kind of mesh; they think all they have to do is plop a point light where a bulb would go in real life, and it works just like the real thing. Except it doesn't, due to facts like light bulbs are acting as diffuse scattering shells for a source of light that is actually linear (look at a filament; not just a point in space, is it). Lampshades typically have white interiors of translucent cardboard, reflecting much of the light from the bulb back inwards (and bleeding some light through for decorative purposes, depending on the kind of shade it is. How much time would it take to model that shade with optically accurate materials or shaders applied to the required layers?), to eventually win free out the top or bottom of the shade, where interactions with the atmosphere and particulates create the perceived cones of light (and I'm not going to even try to get into atmospheric interactions....) The most common cheat? A point light and two spots, one pointing up, one down. The point basically just illuminates the shade for the bulb 'hotspot' and provides a bit of fill; the spots are what actually generate the light cones, and you have far more control over what is actually happening regarding your scene (you want a party environment? Keep the lamp spots at the same intensity, or make the upper one slightly brighter, to give a smoother fill to a scene. Need a dramatic desk shot? Dim the upper and increase the lower so that the eye is drawn towards the brighter area)." Hope that helps you (I know it was useful to me!).