Bokeh

Canon EF 50mm f/1.8 II Lens, F-stop: 3.5

When using a small compact camera in a 'standard' way, most of the time much of the foto is in focus. This is because the sensor of such a camera is small, and mostly, the lens is as well.
With a DSLR, things are very different. Because of the bigger sensor and bigger lenses with a larger aperture, a much shallower 'depth of field' can be created. In other words: a very small part of the image, for instance your subject, can be in focus, while the rest is blurry. This method can be used to draw the viewers attention to the subject. Now, the quality of these out-of-focus areas (especially light points) is described as 'Bokeh'. As you can see in the photo on the right, Hellen is nicely in focus while the Christmas tree is blurry and has become a cool 'Bokeh-tree' in the background :-)
To create a nice bokeh-effect you need a lens with a large aperture, for instance the Canon EF 50mm f/1.8 II. The bokeh photo's in this blog were made with one of these. A smaller F-number means a larger aperture, or larger 'opening' of the lens, and this results in a shallower depth of field (so more blurry-ness in the background...).

If there is no lens available with a low F-number, you can get the same result (more or less) with a zoom lens. However, in order to get the effect you have to zoom in on your subject that is relatively close to the lens while the background needs to be pretty far away. Using this method you can even get the effect with a simple kitlens.

Christmas tree bokeh filter construction

Bokeh filter

Christmas tree shaped bokeh

The shape of the bokeh is highly dependant on the construction of your lens. However, there is a fairly simple way to influence this. With a black, dark or non translucent piece of paper, a sharp knife and some sticky tape you can make your own bokeh-filter. Just cut out the desired shape from the black paper, for instance a christmas tree. Then fold the paper is such a way that you can use it as a lens cover. Put this cover over your lens and shoot. Truth be told, the resulted image shown here isn't the best photo possible. It was a quick 'n dirty test of the bokeh-filter principle, and for such a small experiment it was a quite successful one. As you can see the bokeh-lights now have the shape of tiny Christmas trees.

On the web, you will find a lot of discussion about what good/poor bokeh really is. I think it's about your personal taste and what you are trying to get. So go ahead and shoot some 'Bokehlicious' photo's!