So... you stand on a pier on a dark night. You point your camera towards the city lights across the bay. You set it up for a loooong, sloooww exposure. Then, when you trip the shutter you simultaneously twist the zoom collar on your lens. Ok, I was nearing the end of a long drive, I wasn't happy with the moon shots I originally stopped at this pier for, so I said "what the heck - let's have some fun!"