Mastering Motion Blur—04/11/11
Blur can be a useful tool to communicate speed and motion in pictures
When we’re learning the basics of photography, we’re usually taught that motion blur is bad, but that’s an oversimplification. Motion blur is only bad when you don’t want motion blur. It can actually be a tool in the photographer’s arsenal to help communicate more clearly. Here are a few tips for putting motion blur to work in your favor to create better pictures.
When you want to instill the feeling of motion, nothing works better than motion blur. This can be achieved in several ways, but two of the most common are panning with a fast-moving subject and letting a fast-moving subject turn into a blur. The first approach creates a sharp subject and blurry background. Think racecar photography, where this panning method is necessary to render a tack-sharp subject at 200 miles per hour. Panning with fast subjects may require a shutter speed as slow as 1/8th of a second, or as fast as 1/250th—it all depends on the speed. Generally, though, shutter speeds slower than 1/60th are better for making motion blur. The second approach, where the subject itself is blurry, is much easier to achieve. It simply requires a steady camera via a tripod with a long shutter speed. The faster the subject’s moving, the faster the shutter speed can be. It’s a great way to show motion in context—when the story is less about the racecar and more about the track, so to speak. The approach you take all depends on what will help tell your story.
The racecar example actually illustrates many principles about motion blur. For instance, when a subject is traveling toward you it’s much harder to create motion blur. Why? Because the relative size and position on the sensor doesn’t change as rapidly as it does when the subject is moving laterally across the frame. In practice, that means when you want to freeze a fast moving racecar, position yourself so that the car is moving toward you when you want to photograph it. To make motion blur, position yourself so that the car is moving across the frame so that you can pan with the car or let the car streak by. It may go without saying, but this approach also works with bicyclists and runners and crawling babies and just about any other moving subject you can envision.
When working with a flash, your motion blur options open up a bit. A typical flash fires immediately when the shutter opens—at the beginning of the exposure. With a longer shutter speed, that means any motion that happens after the flash fires will create blur that carries forward from the sharp flash-exposed subject. This can look quite odd, especially when the motion is key to the image. Ideally, a motion blur would happen before the tack sharp subject, as if the blur is leading into the shot. Fortunately many modern flashes offer what’s called Rear Curtain or Second Curtain flash sync. This fires the flash at the end of the exposure, just before the shutter closes. It’s a subtle difference in technique, but it can make a huge difference in terms of effective motion blur.
Look for lights. It may sound simple, but moving lights are a powerful way to convey a sense of movement, as well as to create graphic interest, in almost any photograph. Long exposures with moving lights from cars, planes, helicopters, stars, fireflies, Ferris wheels and flashlights are sure hits. And if you can find a way to combine a long shutter speed with a scene illuminated by many lights, creating motion blur of a moving, illuminated subject, followed by a rear-curtain flash sync to freeze the moving subject just may create the perfect motion blur photograph.
If you’re desperate to make motion blur and your stationary subject just isn’t cooperating, you can always move the camera instead. Sure, it’s a whole different approach to motion, but the little bit of blur from a subtle camera movement can add the perfect amount of dynamism to an otherwise static shot. Fashion and beauty photographer Douglas Dubler once told me that he often uses a slow shutter speed technique to deliberately add subtle motion blur around the edges of models he photographs—specifically because the motion added a sense of depth and vitality to the images. Other photographers have gone so far as to throw their cameras into the air to create abstract images of nothing but motion blur. I’m not suggesting you toss your D-SLR into the air, but the principle can apply more safely too. Move the camera yourself in conjunction with a slow shutter speed and you can create your own blur. It’s the perfect way to get blur if you absolutely needs motion and the subject just won’t do it for you.