Lighting: Distance, Part 2

I did the Lighting 102 exercise I mentioned previously, this image is the result. The exercise is a really powerful illustration of lighting control... the only differences between the four shots above are:

• the only light (one Alien Bees strobe) is half the distance to the subject in each image (beginning at approx. 77 inches in the first shot)
• the aperture is adjusted to compensate for the closer (and thus more intense) light source

Otherwise, the shots are identical. You can see the huge difference in the exposure of the background while the subject stays basically constant. The background is just a bright white foam core poster-board from Office Depot. Here's one cropped to look nicer: