English: You might want to take a close-up photo of something, but if you focus the camera on the closest part of the subject, you’ll find that the background is out of focus. If you focus on the background, the foreground becomes blurred. You could stop down on the lens, which increases the depth of field, but even so the image might not be entirely sharp.

The solution to this problem is called focus stacking. It works by taking a series of images, each focused on a different part of the scene, and combining them using software that creates a final image using the in-focus parts of each image in the stack. To make the stack, one typically puts the camera on a tripod and focuses on the closest part and presses the shutter. Then one carefully focuses back a bit and takes another shot, continuing until the final shot has the farthest parts of the scene in focus.

This is tedious work, and one risks moving the camera a bit while focusing.

Some cameras are starting to have built-in focus stacking capability. You just set the camera on the tripod and focus on the front, then press the button and the camera takes as many images as necessary while shifting the focus back.

The Nikon Z7 has focus stacking capability, what Nikon calls “focus shift shooting”. You set a few parameters and start the process. After a few seconds you have a stack of images that you can process with third party software to make what hopefully will be a final image that is sharp everywhere. I tried it out using a vase of roses set on the counter. The camera made 26 images, which I imported into Photoshop layers and used auto-blending to compose the final image, which you see here. It’s mostly pretty good. If you blow it up, it looks like everything is sharp. But, on closer inspection, you can see that the area between the vase and flowers on the right, where a couple of stems and leaves are, is blurred.

So I tried a popular third-party app, Helicon Focus. But it also failed to render this part of the image sharply. Then I looked through the stack and found that there was indeed an image where the area was in focus. This area was the backsplash on the bar, which consists of random streaks in the granite with soft edges, like what you can see on the bar in the foreground. I guess that the software failed to find convincing edges in this area (and didn’t have much area to work with), so it didn’t fill in that part of the final image and used some other image for that part.

I tried filling it in by hand using the sharp image in the stack. Even an area this small takes a steady hand and several minutes, and even then I was not completely successful. I gained a lot of respect for the software while doing this.