Focus Stacking: An Introduction

Above is a photo of a Belionota sumptuosa from Indonesia. Commonly known as a Tricolor Metallic Wood-boring Beetle.

It isn’t a regular photo, though. It is a focus stacked image.

Specifically, it is 276 photos combined to make a single image. When shooting macro, the depth of field — the distance in front of the lens that is in focus — tends to be really narrow. By taking a bunch of photos where each has a different depth in focus and then combining only the in focus areas from each image, one can effectively create a composite image that is entirely in focus.

So, this is really 276 images taken across about 40mm of camera travel; about 0.15mm of travel between each picture taken.

Since optics are optics and physics are physics, changing the focal plane by either moving the camera ever so slightly (10 to 20 microns per photo, in this case) or by changing the focus depth via the lens’ focus ring, the scale of the subject changes just slightly and anything in the foreground becomes blurry and obscures the background.

All that has to be compensated for and there are a handful of software stacks that do exactly that.

To put it into perspective, this is a single frame in the stack.

Only the tip of the feet and antenna are in focus. The focal plane is so shallow that not even the leg is in focus and the rest of the bug is entirely blurry.

On a lark, I put together a video of all of the frames in the stack followed by the final image. In 4K.

There is nothing about focus stacking that requires a bit of computer controlled technology to move the camera multiple microns per image with crazy studio lighting.

In fact, focus stacking really only relies that you can hold the camera still enough between multiple photos while also changing the focal plane, either by moving the camera or adjusting the focus ring.

For example, the image above is a bit of gooey fungus growing in a fairly dark part of the forest. Normally, such a shot would require a lot of flash, a really tight aperture (high number– backwards), and as slow of shutter speed as possible. In a single shot, there would likely be some bright flash highlights, too.

In this case, I braced the camera on a log, cranked the aperture to relatively wide open so I could have a reasonably low noise (low ISO) image while still having a handheld compatible shutter speed and then shot 11 frames while varying the focus depth via the lens’ focus ring. I did use a flash, but I was able to turn down the intensity a lot, yielding fewer highlights.

So, yes, handheld focus stacking is possible. But hard. Add a cheap, small, tripod and it is no longer hard. Add a focus rail and the options expand. Etc until your wallet is empty, as usual.

2025 Update: Most modern camera bodies now include a focus stacking option. Usually in the same realm of the UI as the exposure stacking controls. They tend to be pretty imprecise in their description; you tell the camera how many frames to stack and a vague idea of how much focus change you want. There are simply too many variables between subject, lens, and camera body to have any kind of precision expressed here. Some cameras – like the Olympus TG-6/7 – will both do focus stacking and post processing in the camera body.