I've been meaning to try some smoke photography ever since I saw it here.
There are some great instructions at that link if you're interested. It looked like a lot of fun. I was messing around in the studio today and I realized that I had a black background already set up and I had incense and everything else I needed right at hand so I had a go at it. It's simultaneously a blast and very frustrating. The smoke does all sorts of wonderful stuff and the flash freezes the incredible shapes, but holy cow is it hard to get it in focus. It hurts to see that you captured some unbelievable shape only to find that it's not in focus. Getting the stuff in focus is very, very difficult. Click on the photos to see more detail.
These first three shots are just straight photos of smoke. The color is natural, but I goosed the saturation up some in Photoshop.
The following shots have the color "inverted"... that is, they are actually negatives of the originals. The color has been played with a little bit using the "Hue" control in Photoshop.
All in all I'd say it was a pretty successful afternoon's tinkering. I'm totally fascinated with the shapes created by air currents. I'm sure I'll do some more of these. The results are so beautiful I think they'd make good art for the walls at home.