How I Do Focus-Stacking Photography

John Neel employs this creative technique with his Tamron macro lenses to achieve a final image with enhanced depth-of-field.

Article by Jenn Gidman

Images by John Neel

Focus stacking is one way that John turns the photographic process on its head. This digital technique increases the depth-of-field in a photo by capturing a series of shots at different points of focus and then combining them using stacking software. John, who has used the technique in his landscape and HDR photography, most often uses focus stacking in his macro work, which he usually accomplishes with the Tamron 60mm, 90mm, and 180mm Macro lenses.

"In macro, the depth-of-field is usually really shallow, which means your images won't have much depth sharpness," he explains. "But with focus stacking, you as the photographer determine the amount of depth-of-field. You can have everything sharp, or you can simply make the existing depth-of-field a bit larger."

To effectively pull off a macro focus stacking shoot, you need to have a subject that's small and doesn't move, as well as a tripod. "You're doing these shots over time," John says. "For the best results, you need your images to be perfectly in line. When it's bright and sunny outside, there are some interesting things you can do handheld, but in most cases, you'll want the camera on a tripod to keep everything stable."

There are three ways to take the images you need for the focus stacking technique: Adjust the focus with the focus ring of the camera; move your subject in increments toward or away from your fixed camera (you can also place the subject on a movable object, such as a large piece of paper, and pull the object toward you in increments); or move your camera toward the subject.

Moving the camera is the technique John used for a recent photo shoot in which he captured his own camera collection. "You should see my office," he says. "I've probably got close to 200 to 300 cameras, most of them old folders, rangefinders, and box cameras. They're all interesting to me because of their history." In this method, the camera was moved on a trajectory toward John's subject (an old-time camera) along a series of focus points. The settings on the camera stay the same for each picture, and all the final shots are layered together in stacking software.

Figuring out how far apart your points have to be to get the best focus-stacking shot is critical to the process. "Depending on the size and scale of your subject and the lens you're using, you have to think about where your focus is and use your lens at a large aperture," John says. "Sometimes I'll stop down a couple of stops just to make sure I have enough depth-of-field to carry me through to the next point of focus. You want overlapping points of focus - meaning there's enough depth-of-field in each slice you're taking to carry you into the next one. While obtaining a greater depth-of-field can be accomplished with a small aperture, the use of a large aperture allows me to control the parts I want to be out of focus."

John might take 30 or 40 shots for each session, which means he'll typically photograph his subject, move it a fraction of an inch or maybe only a fraction of a millimeter, photograph it again, and continue the process until he arrives at what he's determined to be his final focus point. He uses an automated macro rail to help him do the math. "The points need to be close enough to provide a seamless transition between shots," he says. "The macro rail takes the total distance between the first point and last point of focus and moves your subject in increments according to the number of shots you think are necessary. When I'm doing outdoor photography, it's not always possible to use the automatic macro rail, because it needs to be powered, so I'll use a non-automatic rail that moves the camera back and forth with knobs."

After he's got all of his images of the subject, John imports the images into a stacking software and blends them into one image with an extended range of focus. "I'll typically overshoot the number of focus slices and then only process those images that provide the desired range of sharpness," he says.

The best part about John's focus stacking forays? "With macro work, I don't even have to go very far," he says. "I can head into my backyard and spend all day within the same 5 feet."

To see more of John's work, go to www.pixiq.com/user/jneel.