Autostack

Autostack stacks a whole folder of focus brackets at once. It groups the photos into brackets by capture time, then stacks each one. Use it to go through a card full of brackets and find the keepers.

Opening Autostack

Click ⚡ Autostack in the Library mode bar, or choose File → Autostack a Folder…. The setup window opens.

How it works

Pick a source folder. Frames shot close together become one stack, and a pause starts the next. Autostack only looks at photos directly in that folder, unless you tick Include subfolders.
Choose where the stacks are saved. Pick a folder, or tick Same as source folder. Then choose one “Autostack results” folder, or the same folder as each stack’s source frames.
Check the plan. Autostack shows how many stacks it found, how many leftover frames didn’t fit a stack, and whether there’s enough disk space. Keep the computer awake while stacking is ticked by default (see Preferences).
Start it and keep working. The batch runs in the background, at full resolution. A stack you start yourself waits its turn.
Check results as they arrive. A chip at the top of the window shows progress (Autostacking 3 of 12). Click Show for a log and an Open in Library button, which works as soon as the first result is saved. Click ✕ on the chip to cancel.

Checking the results

If StackCheck is on, it reads the results when you browse them. A result with a suggestion gets a blue SC badge on its thumbnail. Click the result to see the notice and its Restack without them button. A missing badge doesn’t mean the stack is fine (see the SC badge).

For badges, save a Macro Studio DNG or Raw DNG, and leave the source frames where the batch put them. StackCheck can’t read a JPEG.

Letting the batch act on the suggestions

Tick Restack automatically when StackCheck suggests dropping frames in the setup window. After each stack, if StackCheck finds frames that hurt the result, the batch stacks the rest again. It saves that as a second file, ending in - StackCheck:

Autostack 003 - beetles - 2026-09-19 14.32.07 Nat.jpg
Autostack 003 - beetles - 2026-09-19 14.32.07 Nat - StackCheck.jpg

The original stays as it was, so you can keep whichever you prefer. The log lists both files.

It works with any output format, JPEG included.
Each stack is checked once. A - StackCheck file gets no badge and no further suggestion (see Stacking again without them).
The original keeps its badge but shows no notice. Use Run StackCheck on it if you want the offer anyway.
The checkbox only appears while StackCheck is on in Preferences.

Options

Output format

Check this before your first run. Tick one or more:

JPEG (small, not re-editable): on by default. Good for spotting keepers, but you can’t reopen it in the Editor to edit or restack.
Macro Studio DNG: a full result you can reopen and edit like any stack. It was called Developed DNG before.
Raw DNG: the same Raw DNG the Save dialog writes, for developing in Lightroom or another raw editor.

If you might finish any of these photos, tick a DNG now. Otherwise you’d have to run the batch again to get editable files.

Raw DNG is grayed out until you turn on Stack RAW photos in camera-raw mode in Preferences. On Linux it always stays grayed out, because Adobe doesn’t make the DNG Converter for Linux. A stack that can’t use camera-raw mode (for example, mixed camera models or a JPEG among the frames) gets no Raw DNG. You still get the other formats you ticked, and the log says why. If Raw DNG was the only format ticked, that stack produces no file.

How the results are named

Results use your file-name pattern, with an Autostack number in front:

Autostack 001 - beetles - 2026-09-19 14.32.07 Nat.jpg
Autostack 002 - beetles - 2026-09-19 14.35.41 Nat.jpg

Autostack 002 goes with the stack 002 folder. In a batch:

{folder} is the source folder (beetles above). For a subfolder stacked with Include subfolders, it’s the subfolder’s name, plus the folders above it if it’s deeper (june - stack 1).
{stack_date} and {stack_time} are when that stack finished.
The species fields are empty.

A subfolder stacked in place gets no number: Autostack - beetle - 2026-09-19 14.32.07 Nat.jpg. Keep {folder} in your pattern if you stack subfolders this way. Results from older versions keep their old names (Autostack 001 - Stack.jpg).

Scope and mode

Include subfolders (stack each subfolder as one set): stacks each folder below the source, at any depth, as one bracket, without grouping by time. Use it when your shoot is already sorted into one folder per subject.
Only split into stack folders (don’t run the stacks): sorts the loose photos into stack 1, stack 2, … subfolders, and stops there.

Try two passes. Run Only split first. Fix anything the timing got wrong in your file manager. Then run again with Include subfolders.

Running Autostack again over a folder you’ve stacked before is safe. It skips its own Autostack results and Autostack leftovers folders inside the source folder. If you pick one of them as the source folder itself, its photos are stacked like any other folder’s.

Stack only

If the folder holds more than one kind of file, a Stack only dropdown lists the formats found, such as CR3 (480) and JPEG (480). Pick one, and the batch uses only those files. The other files aren’t stacked, copied or moved.

You need it when your camera gives a shot’s RAW and JPEG different filenames. Autostack normally pairs DSC_0001.NEF with DSC_0001.JPG as one shot. When the names differ, you get about twice as many stacks, with brackets mixed together. The confirm screen warns you in amber.

Your choice is remembered for every folder.

Source images

Copy into stack folders (originals kept): the default. Each stack’s frames are copied into a stack 1, stack 2, … folder.
Move into stack folders: the same, but the frames are moved.
Leave where they are (no stack folders): Autostack only writes the finished stacks. To undo the run, delete the results. If you also save results in the source frames’ folder, a later Autostack run there will treat them as photos. Save to the Autostack results folder to avoid this.

Advanced

Minimum images per stack: smaller groups become leftovers. This doesn’t apply to subfolders from Include subfolders.
Bracket gap: how long a pause between shots starts a new stack. Raise it if separate brackets are merged. If one bracket is split, read the next section first.

Capture times and the 1-second floor

Cameras save capture time in whole seconds. Some also save fractions of a second, and Autostack uses them. A bracket gap under 1 second only works if your files have those fractions. Without them, one bracket arrives as several stacks plus leftovers.

Autostack checks this. If your files have no fractions, the Bracket gap control steps in whole seconds, with 1 second as the lowest. If your files have no fractions and your gap is under 1 second, the confirm screen warns you in amber.

A file with no capture time (some export tools remove it) uses its file date instead, which isn’t precise to a fraction of a second. Frames within a stack are stacked in the order you shot them, the same way as stacking from the Library.

If Autostack finds nothing

The confirm screen tells you why:

“The images here are inside subfolders…”: tick Include subfolders, or pick the subfolder itself.
“Found images, but none formed a set of N or more shots within Xs…”: lower Minimum images per stack, widen the Bracket gap, or check the capture times.
“No images found in this folder.”: check the folder, and that the files are a supported format.
“This folder has images in it, but none of them is a … file.”: change Stack only to a format that’s there.
“This folder is no longer available…”: reconnect the network share or external drive, and try again.

If one bracket is split across several stacks

Check the Bracket gap first. If it’s under 1 second, set it to 1 second or more (see above). If it’s already 1 second or more, a pause in the shooting (such as a slow flash) was longer than the gap. Widen the gap, but keep it shorter than the pause between subjects.