In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. Photographers call this effect bokeh.
This abstract was created by shooting a peacock feather slightly out of focus with a very narrow DoF. I then accentuated the bokeh slightly using Photomatix.
Color Me a Rainbow – September 2011
Nikon D7000 | Lens AF-S Micro-Nikkor 105mm f/2.8 IF-ED
f/4.5 | 1/60 | ISO 200 | RAW