I know this has been done before, but here's my first attempt at it. I was looking at Crux on Saturday night and decided to have a go at capturing the star colours by taking several images while pushing the lens more and more out of focus. The out-of-focus starlight is no longer overexposed, and the colours are therefore revealed. Here is an image made up of several 15 second exposures stacked in PS7.
Maybe try de-focusing in smaller increments too and get a more smooth effect? I think it would look awesome.
