I have a Nikon n80. 1) I want to take pics of a car passing by. I want to blur the car and have the background remain sharp. Naturally, I will use a tripod. What shutter speed (1/15, 1/30?) should I set the camera to, and how fast should the car be traveling. (5mph/10mph?) 2) I also want to pan and blur, where the passing car is somewhat sharp, and the background is totally blurry. How fast should the car be traveling, and what shutter should I use. I probably will not use a tripod for this. This will be a controlled environment, and I will not just be taking pics of random passing traffic. 3) Lets say its a person running. Most people run at around 5-10 mph (guessing). So If I want to do these pan and blur tricks, what shutter speed is appropriate? Any tips are welcome. Thanks.