Well after a lot of positive emails about the previous post, I thought I would post another link to a very good explanation of Depth of Field. This one is a little more dtailed, naturally, but just as good a read.
Remember, DOF can greatly affect a photo. It helps to put the attention on a particular point. Also, it isn’t just things in the background that you can throw out of focus. Things in the foreground OOF can help a photo too. Here are a couple of examples.
This is a perfect example of the background thrown out of focus. I only wanted the sugar container in focus on that photo, so I set a low F stop, f/5.6, and focussed on the container itself.
You can still see the other sugar containers in the background, but they aren’t the focus of attention.
In this example, I have again gone for an f/4.5 and focussed on the musician on the right and the one to the left is out of focus (OOF)
I hope that helps. I know when I realised you could actually control this sort of thing, my photos started to look better.