Bokeh simply means fuzzy or out of focus, and it is used to refer to the effect of shallow depth of field that creates a pleasing blur of color. There’s no better time to play around with bokeh effects than right now. Christmas lights are the perfect bokeh backdrop. (No colored lights on my tree this year… vibrant colored lights produce the best backgrounds for the bokeh effect.)
A shallow depth of field can be achieved by widening the aperture (the size of the hole in your lens) — remembering the smaller the number, the larger the aperture. If you don’t have access to a lens that allows you to blur the background as much as you’d like for the bokeh effect, try positioning your subject of focus farther away from the background of lights.
Around Christmastime in 2010, I explained how to use a piece of thick paper to create an interesting bokeh technique that adds distinct shapes to the background lights. If you didn’t try it back in 2010, I hope you give it a whirl this year!