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I wanted to ask, can you use the ambient light square WITH a spotlight, or must this square be used by itself to get the effect that you've demoed?

Automatic conversion is no good idea. Use light-emitter where you can. I did a lot of tests with light. If you want real light, avoid standard-lights and use environmental-light and/or light-emitters. 

By the way: It makes a difference wether you us a "flat" square as lightsource or a geometry with a more or less bend surface (up to a sphere).

Or try a square expanded in the X-direction. With a bit experience you will get really good images. Because lighting is most important (more than a texture).

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