Zooming out with a slow flash

Some days ago I tried this technique with some unsuspecting subjects at home... Gear: Nikon D700, AF-S 24-70 f2.8 lens, and a Nikon SB-600 flash set to bounce light from the ceiling.

Basically, it just takes setting the flash at Slow, and the ISO at 400 OR 640 (anything below 800, but then it also depends on the environmental light). With the camera in P exposure mode, I simply turn the zoom ring while the shutter curtains are open (which can be about 1 second). Here are the effects...

Edmund, the ghostly kid, prances about while I photograph him with a slow flash while zooming out a little. The effect is weird...

Here we go again... his head is blurred in the edges, as if he were a child in a Fringe episode.

This is the best of them; his head seems to blend with the book behind. He must have moved at the same time I shot, and if we add the slow zoom out, the effect is quite scary.

Why did I get into this? Because one evening, Mimi was keeping me company and it occurred to me that it would be a good moment to use her as an experimental subject. Which I did...

Unlike other warnings we find elsewhere... go ahead, try this at home. In fact, I'd like to do this at a wedding, just for the heck of it.

Of course, my other photos of Mimi on top of the chair may come up here later... just to show what happens when you point the flash head to the ceiling, or to the wall behind you.