Whether you’re shooting macro subjects like jewelry and flowers or landscapes on the latest high-resolution bodies, controlling depth of field can be essential. Focus stacking, where you combine multiple exposures at different focus points, can completely change the game when it comes to tricky depth of field situations. When you don’t have to worry about stopping down or picking what’s in focus, you can be even more creative. Fortunately, it’s easier than ever to properly focus stack. Check out this guide to the best field and post-production practices.
As mentioned, focus stacking involves shooting a series of exposures, moving the focus point a small amount between each shot. This set of exposures then contains a wider cumulative area of focus compared to even a significantly stopped down single photo, and these shots can then be combined in software to produce a final image.
Technique
The basic setup goes: choose an exposure and set it manually, disable adjustments like auto ISO, and move focus to the nearest point in your image that you want to be in focus. From here, trigger the shutter, then move the focus point back ever so slightly. Ideally, you’ll just be shifting the in-focus area back, not changing it entirely. Continue to move the focus point back and take photos at each point, until you’ve reached the farthest back point you want in focus. If you’re going to try again or shoot a similar composition, I like to take a random picture of the ground just to separate the different stacks in Lightroom.
There are a few things to keep in mind when shooting, regardless of which method you choose to capture the frames. The first is that you can’t take too big of a step between each frame. If you move the focus beyond the point where the two frames have the in-focus areas overlapping, you’ll end up with a subject that has alternating bands of focus and blurred areas. That stack is ruined, and you might not know until you get back to the computer, so err on the side of too small a movement, compared to too large.
The next is that if you’re shooting the stack by hand (not advised), make sure to lock in your exposure on the first frame. Each frame needs to be as consistent as possible, other than the focus point, and exposure changes can cause issues. Also, while you could shoot very small stacks handheld, it’s going to be much more difficult. When getting started, make sure you’re on a sturdy tripod, locked down.
Finally, consider the impact that focuses breathing will have on your composition. Focus breathing is the effect where changing focus will subtly change the focal length of the lens. A shot with focus as close as possible could show or conceal things at the edge of the frame compared to a shot with a focus set back. When setting up a composition, consider moving focus through the range while looking through the viewfinder to make sure that everything you want in the frame will still be there throughout the stack. Stacking is one instance where a little preparation goes a long way; with 20 shots in a stack, a settings mistake can mean a bunch of extra work.
To create this set of exposures, you’ve got a couple of options depending on your subject and gear. The easiest solution is to just manually move the focus ring a small amount between each exposure. For macro subjects, this might require a tiny adjustment between each shot, which is where a dedicated macro lens’s big, finely geared focus ring comes in handy. When photographing and stacking larger subjects, where you have more margin for error thanks to the greater depth of field, you can use any lens’s manual focus ring, or even just use autofocus to focus at a few different points throughout the frame. Professionals often use a sliding focusing rail.
If you have a newer camera, you may have a great option built right into your camera. Some newer bodies support focus stacking right in camera, with the camera’s focus motor performing the same steps that you would manually: capturing frames, adjusting focus, and repeating until finished. For example, my Nikon Z 7 supports focus stacking. Check your camera’s manual or Google for more information. Typically, the implementation will let you select the size of the focus steps, the number of frames, and additional perks like automatically locking the exposure on the first frame.
Processing
If you’re just getting started with focus stacking, Photoshop makes things easy. Photoshop supports blending a stack of images and does a pretty good job. As the stack gets more complex, larger, or you become more demanding in your workflow, there are some dedicated stacking tools, but first, we’ll just look at the Photoshop workflow.
In my workflow, I import and edit the images in Lightroom, performing the basic color and contrast adjustments. Lightroom makes it quick and easy to sync these changes across the images in the stack. Also, if you didn’t set a manual white balance in the camera, make sure you’re setting one now for your raw files. Remember that we’re trying to keep these files looking as similar as possible.
With the adjustments made, select all the files in the stack, right-click the selection, and choose Edit In, Open as Layers in Photoshop. Depending on the size of the stack, this might take a few seconds. Once it’s done, you’ll have a single file in PS with all the individual shots in layers. Shift-click the bottom layer to select all the layers, then Edit, Auto-Blend Layers. Select “stack images” if it isn’t already active, then click OK. From here, if the images are shot properly, Photoshop will go to work blending them.
The final result will be a set of layers, with each frame having a mask to reveal only the in-focus areas. While you can manually adjust these masks if necessary, I’ve found that the final result is usually good enough. To save time when making adjustments to the stacked image, I’d recommend you flatten the image. Flattening will collapse all the individual layers into a single one, drastically cutting memory usage.
Conclusion
Focus stacking doesn’t have to be complex. Cameras have made it very easy to shoot a clean, usable stack, sometimes with just a few clicks. At the same time, higher-resolution bodies have lowered the diffraction limit, making an alternative to stopping down to f/16 all the more useful. Lastly, faster computers and better software support have made stacks quick to process. When you’re photographing landscapes or 1:1 macros, consider shooting a stack next time! The result can be visually impressive, and it’s a great technique to have.
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