The skateboarders here represent just that. To decide which combination of shutter speed, panning, and flash pop worked best, I ran a range of shutter speeds, going from a conventionally fast 1/400 sec to an improbably slow 1/4 sec. I used the Canon EOS 20D with a Sigma 12-24mm set to around 12mm. In order to freeze facial expressions, I aimed an off-camera White-Lightning X3200 flash directly at the skateboarder's face, sharply capturing the eyes, while letting the rest of the image blur as it might. An additional bonus of using flash: It let the background darken, drawing attention to my subject. You may wonder how I was able to shoot at 1/4 sec in broad daylight without overexposing the scene. Answer: A 3-stop neutral density filter and f/11 aperture.