How to Keep Your Subject in Focus When Shooting Long Exposure Photography

Have you ever taken a long exposure at dusk only to find you snapped a shot filled with amazing light trails and a blurry subject? Most photographers agree this can be a tricky scene to shoot, especially if you’re trying to keep a main subject in focus and shoot without a tripod.

Photographer Joe McNally ran into this type of lighting situation when he visited the central business district of Beijing to capture graphic pictures of the new skyscrapers being built. After hanging off the ledge of a building 65 stories in the air, clipping a flash to a steel beam, and creating a makeshift light blocker, he created this tutorial to teach you how to get that perfect shot:

McNally explains the driver in this situation is the ambient light level resulting from the darkening city. The lower light level will naturally result in a longer shutter speed, which will ultimately risk his subject (the welder) being out of focus in the photo.

Ideally, McNally says he wants to showcase the tracer lines created by the showering sparks and moving traffic, but he also wants the focus of the photo to be the welder.

“But what’s the danger zone? Your picture will be very unsharp if shot using the available light. I’d have a very unsharp mess on my hands.”

To remedy the situation, McNally mounted a Nikon SB-910 TTL AF Shoe Mount Speedlight Flash on a Manfrotto 175F1 Spring Grip Justin Clamp, attached it to a nearby beam, and focused the light directly on the right side of the welder.

night photo flash

The final photograph combining the light trails of the traffic and sparks with the welder in focus. (Focal length: 12mm, ISO: 100, Aperture: f/6.3, Shutter: 2 seconds)

“So, the mechanics are fairly simple. One flash–freezing my subject, or sharpening the subject, and then the rest of it becomes an available light exposure. The challenge for me is to hold my camera steady during that time, and let the flash do its work of sharpening the image for me.”

McNally said the only other issue he encountered was the bright light resulting from the actual welding itself. He moved a piece of steel over to cover the welding site and even out the exposure.

“And that’s it. One light and the power of the speed of light. Flash gives you a chance to stay sharp. Even when you’re hanging off a building with one hand and a two second hand-held exposure.”

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