StackCheck (Beta)

A focus bracket usually has a few frames that don’t earn their place. One went soft because something nudged the rig. One caught a flash of different light. The run started or ended a little wide, so the first or last few frames sit entirely outside the subject. Those frames don’t just fail to help. They can drag detail out of the finished image.

StackCheck looks for them. After every stack it examines what each frame actually contributed, and if something stands out it says so in a short amber notice above the canvas, with a button to stack again without those frames.

It stays quiet

This is the part worth knowing before anything else: most stacks produce no notice at all. StackCheck only speaks when it has something specific to point at. A suggester that pipes up after every stack is one you’d learn to ignore, so it’s built to say nothing rather than to reassure you.

No notice does not mean “every frame was checked and passed”. It can also mean StackCheck couldn’t tell. A two-frame stack has no neighbours to compare against, and some stacks don’t produce the measurements it needs.

What it looks for

StackCheck works from what the stacker already measured while building your image, so it costs nothing extra and needs no second pass over your frames.

Frames that went unused. For each small region of the picture, the stacker knows which frame was sharpest there. A frame that won almost none of them contributed essentially nothing to the result.
Runs at either end. Unused frames bunched at the start or end of the bracket are reported together, as “the last 12 frames look unused”, because that’s usually one thing that happened rather than twelve separate ones.
Frames that barely contributed. A frame winning far fewer regions than the frames on either side of it is often soft.
Frames that sit out of line. Alignment shifts should move smoothly across a bracket. A frame that jumps away from the trend its neighbours follow usually got knocked.
Frames that wouldn’t align. Sometimes alignment can’t find a solution for a frame at all.
Frames lit differently. A frame noticeably brighter or darker than its neighbours: a flash that didn’t fire, or fired twice.

It does not look at how far a frame is turned or magnified on its own. Those change smoothly across a bracket, magnification especially, since focus stacking works by changing focus distance and that changes magnification with it. Alignment corrects for both. A frame that turned is only reported when the turn pushes it out of line with its neighbours.

When most of the bracket looks damaged, StackCheck deliberately gives you no list. A hit list that long isn’t a suggestion, it’s a different problem: the whole set failed to align, or those frames don’t belong together. Picking frames off it one at a time won’t help.

Stacking again without them

The Restack without them button stacks the surviving frames, exactly as if you’d selected them yourself in the Library. It goes into the same queue as any other stack, lands as its own entry in the history strip, and leaves your original result untouched so you can flip between the two and judge for yourself.

Nothing is deleted. StackCheck never touches your files, never changes a selection, and never alters a stack you’ve already made. It only offers to make a new one.

Because it drops frames, the new stack is usually quicker than the one you just waited for. How much quicker depends on how many frames come out.

The notice belongs to one stack

The notice is about the image on the canvas, so it follows what you’re looking at:

Click another stack in the history strip and the notice goes with it, so you’ll see that stack’s suggestion, or none.
A stack that finishes in the background while you’re looking at something else lands quietly in the history strip and says nothing. Click its thumbnail when you’re ready and its suggestion appears then.
Close the notice with the ✕ and it stays closed for that stack, even if you navigate away and come back.

Turning it on and off

Preferences → General → Enable StackCheck (Beta) — suggest frames to drop to improve a stack. It starts switched off.

The setting controls the notice only. It changes nothing about how your stacks are made.

What it can’t do

It never deletes a file, changes a selection, or alters a stack you’ve already made.
Restack without them builds a new stack and leaves the original in the history strip. Compare them and keep whichever you prefer.
Its advice is not always right. It’s a suggestion, not a verdict, and while it’s in beta you should expect to disagree with it sometimes.