How to focus stack landscape photos in Photoshop
“One of the most appealing attributes of landscape photographs is sharpness from front to back. Everything is in sharp focus in the foreground, middle, and background, allowing the viewer to be pulled into the image as if they were standing right there.” – Max Foster
Generally speaking, sharpness throughout the image, that is from foreground to background, is far easier to achieve with an ultra-wide-angle lens (UWA) than with a tele. However, even wide-angle lenses have their limitations. If you place a UWA lens only a few centimeters from the foreground object, you can get it in focus. The background, however, will fall outside the depth of field and be blurred. The same goes if you focus on a very far object.
You may stop down to a very narrow aperture, like, for example, f/22. It will make it easier to get everything in focus. You will get a decently sharp foreground. However, the middle ground and background will be soft due to diffraction.
There is a better way: Focus stacking.
What is focus stacking?
Focus stacking is when you “stack” many similar photos together and use only the parts that are “in focus” from each of the frames. This is a common technique for macro photography when the depth of field is very narrow.
For landscape photography, you would use it when you can’t get both the foreground, the midground, and the background all in focus in a single frame. I, for example, primarily use focus stacking when I go low and place the camera very close to a foreground object. I have tried to focus stack my way through a scene handheld. That was a nightmare, so a tripod is a must.
How to focus stack for landscape?
Below you will find my “recipe”. It provides an excellent base; feel free to use it as it, to adapt or to change it entirely depending on your needs.
If the light is good, I start by shooting the background. I do this, just in case, the light will change during the focusing process. Next, I set the camera to live-view with focus peaking turned on. I make sure my immediate foreground is in focus first. After I have made the shot, I turn the focus ring a little further and shoot the next exposure. The further I move out into the scene, the larger are my focusing adjustments. The near foreground is usually most critical. It requires incremental focusing adjustments. Needless to say, that when you focus stack, you should set the camera or lens to manual focus.
There are now cameras on the market, like the Nikon D850, which have automated the stacking process. No manual labor involved for the photographer. Some camera models with a touch screen, like the Canon 5DmkIV, implemented a touch-to-focus functionality. This, of course, also simplifies focus stacking in the field.
If you need a fast shutter speed (because of wind, for example), you can increase the ISO or open up the aperture. Take into consideration that the more open the aperture, the more exposures you’ll need. Getting a sharp image at f/5.6, for example, will require more exposures than f/11.
An open aperture offers less depth of field than a narrow. When possible, you can try shooting at f/22 for the immediate foreground and perhaps at f/11 for the rest of the scene. This approach demands a stationary foreground object, and no wind if the foreground consists of flowers or foliage.
A narrow aperture allows less light to the sensor and will increase the exposure time accordingly. This is, of course, very unfortunate if it is windy.
A telephoto shot with many elements in the frame, each at a different distance from the camera, will most likely also require a focus stack.
An example frame
The photo above was taken at a lake in Ringerike, Norway. It is afternoon. Sunsets are early in January. The light is fantastic. Frost smoke diffuses the light from the setting sun. The atmosphere is magical.
I have already shot the scene from various angles, and decided that I wanted a very low photo. I placed my tripod as close as possible to that foreground bush. I first shot a couple of exposures for the background. One of them is very underexposed. I will mask it in where the sun is because the light from the sun is difficult to control in this instance.
Then I concentrated on the foreground bush. When I got it in focus, I hit the shutter. I then moved the focus ring a tad before I shot my second exposure. I am shooting at ISO 100 and f/11. All in all, I took six images with various focal points. I assumed that at f/11, this should suffice.
Blending the exposures in Photoshop
After prepping the raw files in Lightroom, I opened them as layers in Photoshop.
Since I rotated the focus ring, there will be a slight shift in perspective between the photos. The first thing needed is to align the six images. Here is how you do it:
Highlight all the layers by clicking the bottom layer and then Shift+click the top layer.
Go to Edit and chose Auto-Align Layers.
A pop-up window appears. Make sure Auto is checked and click ‘ok’.
Now you need to make a copy of the layer stack. With all layers highlighted, drag them down to the plus icon at the bottom of the Layers Panel. If Photoshop makes any mistakes in the blending process, you can use the copied layers to fix any blending errors. (I do this because once the blending process is completed, It is very hard to use the original layers for masking. I have tried, and that was a very frustrating experience).
Click the eye icons to turn off the copied layers.
It is time to blend the images. Again, go to Edit, but this time choose Auto-Blend Layers. Don’t forget to highlight the original layers before you start the process.
In the new pop-up menu, make sure that Stack Images and Seamless Tones and Colours are checked. I prefer to fix the edges myself after the blending, so I leave Content-Aware Fill Transparent Areas unchecked. Now click ‘ok’.
Here is the Layers Panel after the blending process. The white areas in the Layer Masks show which parts from each image Photoshop used to output the sharpest possible image.
Now, begin to zoom into the image and look for any blending errors. If you find a mistake, click through the copies until you find a sharp image you can use for that particular spot. Then, add a black mask to the layer. Use white as the foreground layer to paint in to cover the blending mistake.
If it was windy, and the various objects in the scene moved around, you can expect quite a masking job. It will also be necessary to use the clone tool quite a bit.
In this instance, there was no wind. Also, Photoshop blended the six images flawlessly. I only turned on the bottom copied layer, which was focused for the background, and added a black mask. The sky looked more exciting on that layer.
Once you are happy with everything, you can delete the copies you haven’t used. Next, flatten the image before any further editing.
Her is the final result, a few Photoshop layers later: