How to Pan in Photography (by Kim Linton, eHow Contributor):
#1 - Choose a subject. The object or subject of your photo must be in motion in order to create the pan effect. Subjects like moving cars, roller coasters and marathon runners make great pan shots.
#2 - Designate a focus point. Pick a focus point to determine when you will take the photo as you pan. It could be as the subject passes a certain object, like a tree or road sign for example.
#3 - Set the shutter speed. To focus on a moving object you must use a very slow shutter speed. For example, a good shutter speed for a marathon runner would be 1/30 of a second. Adjust the shutter speed as necessary for objects that are moving faster or slower.
#4 - Set up your tripod. Use a tripod to keep your camera level while panning. Simply rotate the camera left or right to pan with a tripod. If you don't use a tripod, and your hand is not steady, you will produce a vertical blur and ruin the shot.
#5 - Take your shot. When you see the subject coming, hold your shutter down half way and follow the movement of the subject. Lock your feet, swivel with your upper body, then hit the shutter when the subject reaches your focus point. Always follow through and keep your movements smooth to produce the best results.