One criteria almost all of my photos need to satisfy is that they have to be “sharp.” In photography that means that they need to be properly focused and that the shutter speed needs to be set so that the subject isn’t blurred.
But sometimes I break the rule. This photograph is an example. I intentionally set the a low shutter speed and then I moved the camera by following the bicyclist as he moved across my field of view. In this particular case, I knew that blurring – both of the bike and of the background – would lend a feeling of motion to the photo.
Canon 5DII 1/10s f/13.0 ISO100 58mm