Subjects in Motion – Zoom Bursts
Another great technique is to physically zoom the lens barrel during the exposure. You’ll need to experiment, but start with a shutter speed of half a second or longer and, if possible, use a tripod. Try different zooms such as 28-80mm or 70-300mm, and vary the zoom range and starting point for different effects.
Nikon D2x, 110mm, 1/10sec @ f/10, ISO 200 Tim Gartside