Photography, Digital Photography, Macro Photography.

Focus Stacking for Greater Depth in Macro Photography

There is more than one way to shoot a snake (skin).

The shed 18-inch skin of a garter snake found while mowing our lawn. Much larger than life-size, but no idea how much. — All photos herein ©Charles G. Haacker, Author.

“Stacking” your focus on stationary subjects increases the apparent depth of field.

Do you like to make big (macro) pictures of small subjects? I sure do! I use two techniques: racking, using a focus rail, and refocusing the lens. Both work, but refocusing the lens works if you’re just trying this out. Racking with a rail is best for high precision at very high magnifications but may be limiting if your subject is longer than your rail.

Let me caution you not to buy a cheap rail. I did, and it was so frustrating to use that I hardly ever used it. The one I have now cost USD 200, but its build and worm-gear precision make it more than worth it.

The snakeskin was way longer than my rail. Manually refocusing on it incrementally was the solution. My main focus would be the head with that remarkable forked tongue.

..garter snakes are usually 2–3 feet in length when full grown. However, Common garter snakes have been recorded in lengths nearing 4 feet. At birth most garter snakes are less than 6 inches long. They grow little from birth in the late summer until their first spring. — Nebraska Extension Wildlife

Now you know; our garter snake may be middle-aged. Let’s call him Garry.

Say hi, Garry. Oh. Wait… Research establishes that garter snakes, at least, do have skin on their tongues that they shed when moulting, leaving a cast of the tongue.

Above is the result of Garry Garter’s aligned and finished stack. The original critical focus was on the skin on Garry’s fork-ed tongue. (Full disclosure: there was some schmutz between the forks that I cloned out for clarity.)

Below is a quick and dirty (mostly dirty) glance at my small object set.

What’s that they say about a messy desk…? (Asking for a friend.)

The main (and only) light is a hardware store clamp lamp on a boom with a 100-W (equivalent) LED household lamp and a diffuser made by sticking a Voldemart bag over it. (Seriously??) Yeah — whatever works. The bulb is cool enough that the bag doesn’t melt.

The set-up for the first exposure was critically auto-focused using the medium moveable spot. After each exposure, I moved the cursor further along the skin for nine frames. It’s imprecise, but it got the job done. Full manual focusing would have been better but my eyesight now precludes it in low light.

I wanted a spotlight effect on the head, so I used an old-school trick with a convex (7X magnifying) makeup mirror to pick up the single light above and redirect it, focusing on the critter’s face. That’s the mirror on the left.

I shot at one second @ f/16, a scoche more DOF for “fudge room” as this was not a precision job, just a record for my granddaughter for when the skin is long crumbled to dust.

The first, fourth and ninth frames from Garry’s stack. I’d have done better manually focusing but eeeeh — Granddaughter never complains. Yet.

It’s not a great picture, but it may inspire you to try the technique. You need a processing application with layers, so you can’t do this in Lightroom.

More stacking techniques and examples.

Focus Stacking

Mad for Macrophotography

Three years ago, I wrote some stories (above) on this sometimes baffling procedure. Many, if not most of you, know that you have several means of increasing apparent* depth of field (DOF), including stopping down your aperture, but the closer you get to a subject, the harder it is to keep everything in focus, front to back. In macro photography, you work very closely at high magnifications, as much as 1:1 or even more. Stopping down to f/22 (usually the smallest aperture on most lenses) will not improve things and may even degrade the picture due to another phenomenon called diffraction.
* Depth of field is illusory. There is only one infinitely thin plane of critical focus. Stopping down your lens aperture creates the illusion of greater sharpness both before and behind the focal plane, but other factors limit it.

By definition, Focus stacking is the making of multiple exposures of an object or scene from a fixed position (tripods help), refocusing for each exposure to have a series from front to back (or vice versa) that may then be “stacked” and combined into a single Übersharp photo in post-production.

One way of thinking about it is slicing a carrot; you take thin “slices” of an object and reassemble them into a whole.

I used Adobe Photoshop 2024 (desktop) and Adobe Lightroom Classic for all these examples.

The spider is a long-leg cellar spider in the bathroom. Its body is smaller than a grain of rice. The filaments of the web are impossible to see against the white baseboard. The flowers are common grape hyacinths. The closeup is about four times life-size. I spritzed on some “dew.”

My granddaughter bought this geode at a rock show. Grampa'parazzo was tasked with photographing it. It was hecka fun.

The left picture shows the setup I used; the right picture is of a fragment of the crust. The break was not clean; the crust shattered. The ordinary drugstore makeup mirror (3X convex side) in the scene focuses a spot of light on the back of the geode to illuminate the thin spot.

My granddaughter (nine) bought a geode at a rock show. She whacked it with a claw hammer to open it up. Grampa’parazzo wanted maximum detail in the crystallization, and if you know me, you know that means…

BACK LIGHT!*

*There is no light like backlight. — Chuck Haacker

Focus stacking the geode using a one-light setup with a mirror assist:

There was a fortuitous thin spot in the crust opposite the breach. I used a single high, slightly rear light on a boom and a 3X convex makeup mirror, visible in the setup shot, to direct a faux spotlight onto the thin place on the back of the geode. The frontal fill was only the ambient. I think the setup worked well. I was formally trained for commercial photography and did loads of small product work; mirrors are your friends!

I used a NiSi Macro Focus Rail to refocus through the entire geode in two mm increments (my $pendy new worm-drive focus rail is Überprecise, which is why it was $pendy).

FROM AMAZON — NiSi Macro Focus Rail NM200s — 360° Rotatable Stable Macro Slide/Macro Adjustment Slide/Macro Focusing Rail for Macro Photography

Three of the nine consecutive frames that made up the stack of the geode. On the right is the completed stack from Photoshop after processing in Lightroom.

Above are three of the original nine 2mm exposures plus the finished picture after aligning and stacking in Photoshop 2024. I used the precision focusing rail to move the entire camera and lens as a unit forward or backward while keeping the focus fixed on a specific point. With this technique, the lens isn’t refocused.

I start by manually focusing my Sigma 70mm f/2.8 Art DG Macro for Sony FE on the nearest feature of the object, take a shot, then rack the camera and lens closer to the object by 2 millimeters, take another shot, rinse, repeat. You can just as easily start at the rear and rack away until the front comes into critical focus.

The higher the magnification, the more frames (slices) are needed, sometimes dozens. For frequent use, powered automatic rails can adjust the camera/lens unit in preset increments, such as nanometers. This allows you to go for a cuppa while the rail does its job, but don’t shake the floor! 😁

A two-shot focus stack outdoors

Instead of stopping your lens down, you can employ stacking, focusing on the near, mid, and far, using a wider aperture. One downside I can see is movement during the three exposures. If it’s windy, you will likely see smearing and blurring in the vegetation.

My first and so far only attempt at focus stacking in landscape.

I have only tried focus stacking in landscape once as an experiment. I liked the echinacea in the foreground but wanted to keep the tiles in the background sharp, which were perhaps ten feet from the flowers.

I didn’t have a tripod with me, so the two refocused frames were handheld. I was surprised it even worked, but there was no wind to stir the flowers, and I was on my knees sitting on my heels, so I had a stable platform. (That tells you how long ago I did this ‘cuz I couldn’t now). I don’t think I manually refocused; I probably used the moveable focus point.

Welp, I think that’s enough for today, children. Be sure to read chapter fourteen in your textbooks. There will be a quiz on Friday.

📸As always, gratitude for looking in. I sincerely appreciate it! Questions in the comments will be answered promptly, so please ask.😊👍

I linked to the article below because, apparently, some high-end professional cameras have onboard focus bracketing, which makes focus stacking in post unnecessary. My cameras are “prosumer” and would never have this feature but it sounds swell.
(NObody says “swell” anymore!)

How Your Camera's Focus Bracketing System Works