When we set out camera to P (Program) or Auto the camera will select the best (it thinks) apertures and shutter speeds. But what if we want to freeze movement – for example to a swishing cane?
When something in your photograph is moving a slower shutter speed will allow it to blur as the movement continues during the exposure. Faster shutter speeds may freeze the motion; depending on how fast the object is going. See Beginners Guide to Spanking Photography