Shutter speed is critical to catching motion, thus sports photography is often done in shutter priority mode or manual. A frequent goal is to capture an instant with minimal blur, in which case a minimal shutter speed is desired, but in other cases a slower shutter speed is used so that blur shows to capture the motion, not simply the instant. A particular technique is panning, where the camera uses an intermediate shutter speed and pans with the subject, yielding a relatively sharp subject and a background blurred in the direction of motion, yielding a sense of speed – compare speed lines.