Blurred background

[dsn]

Here are some shots I took with a D200 ... I wanted to try the blurred background while my daughter was on the swing. But because the swing was moving, some of the swings shots came out blurry. Any suggestions on how to get the moving swing right?

[suprspi]

I'm a new photo nut, but here is my take.

Blurred backgrounds are because the depth of field is narrow - this means the things that are in focus are in a small depth. (Someone has to explain this better.) Smaller F-Stop #'s (larger aperature, more light through lens) creates shallower depth of field, large fstop #'s (tighter aperature, less light through lens) creates deeper depth of field.

So, If you have shallow depth of field, and you are focused on a swing in it's midpoint, it will be clear, the background blurry. If the swing moves backwards or forwards out of your depth of field, it will become blurry. The solution is to have a fast shutter speed (for stopping motion) combined with focusing on where you want to the picture to occur (Back, middle, front of swing's arc) and then snapping the shot when the subject is in the correct depth of field.

Hmmm...I hope that made sense. There is a good tutorial around here explaining DOF, much better than I can.