Everyone has seen pictures like this with points of light in the background. The technique where shallow depth of field allows you to throw everything but the subject out of focus is known as Bokeh. What I’ve always noticed is the way points of light look in the out of focus area. I also learned that you can shape them, and when I finally got around to it I made my own:
For more info on how it works and all the nerdly stuff, hit the jump.