The Classic Zoom During Exposure Trick
One of the reasons for using the classic “zoom during exposure” technique is that it helps eliminate background clutter but the main reason is that it’s fun. Using a digital camera makes it easier because you can immediately evaluate your exposure and make any needed corrections instead of waiting for film to be processed.
Tip #1: Do it in-camera. Pick a subject and make your exposure reading but select the smallest possible aperture in order to produce a slow shutter speed. You may need an ND filter to slow the shutter speed even more. If you want some things in the image to be sharp use a tripod. Immediately after you start moving the zoom ring, trip the shutter and keep zooming after the shutter is closed so the overall effect will be smooth. If you zoom in from the longest focal length to the shortest the effect will be different than if you zoom out from the shortest to the longest.
Caption: This unmanipulated image (above left) was captured in the akihabura section of Tokyo using a Canon EOS Digital Rebel T2i and an 18-55mm zoom lens. Exposure was 1/6 sec at f/29 in Aperture Preferred mode and ISO 400. A minus one and one-third stop exposure compensation was applied. ©2012 Joe Farace
Tip #2: Do it in Photoshop: Create a duplicate layer in Photoshop then choose the Radial Blur filter placing the originating point where you wanted the zoom to start. Next use the Eraser tool on the new layer to remove areas you want to be clear and let the original image show through the background layer.
Caption: Using a similar non-zoomed akihabura photograph (at right) that was made with an exposure of 1/25 sec at f/22 and ISO 400, I applied a duplicate layer with Radial. Since the effect is different when used with a light background than a dark background, you’ll need to experiment. And isn’t that what photography is all about? Have fun! ©2012 Joe Farace