Support
Almost always the frames. Every tool here needs several photographs of the same scene — a folder of unrelated pictures cannot be merged into anything. For the focus stack the frames also have to run in order from one end of the focus range to the other; drag a row to fix a set that arrived shuffled.
More than you think. A focus stack wants enough that every part of the subject is sharp in at least one frame — for macro that is often forty to a hundred and fifty. Averaging takes noise down by the square root of the count, so four frames halve it and sixteen quarter it. Removing people wants eight or more, spaced out in time, so that whoever is walking through is missing from most of them at any given spot. Trails want as many as the night gives you.
A picture of the decision the app made, one pixel at a time. For a focus stack it is depth: warm where the result came from the near frames, cool where it came from the far ones, and grey where nothing was in focus at all. For trails it says which frame left each mark. For the removal tool it shows what was thrown away — grey where every frame agreed, red where frames were discarded, which is to say exactly where something was removed.
Something is removed when most of the frames disagree with it at that spot. A person who stood still for half the frames is, as far as the maths is concerned, part of the scene. Shoot more frames, further apart in time — and if somebody has genuinely settled in, the retouch brush will paint a frame that does not have them over the part that does.
For a focus stack and for averaging: yes, it is on, and it is what makes hand-held sets work. For trails it is off and should stay off — the subject moving between frames is the picture, and registering star fields frame to frame leaves no trails at all. For the removal tool it is off for a subtler reason: registration looks for the strongest thing the frames have in common, and in a set whose whole point is that something moved through it, that can be the very thing you are removing. Use a tripod, or hold still, in preference to switching it on.
It is the width of the window the focus stack measures detail over, and it should be about the size of the worst defocus blur in your set — around 8 to 12 pixels for an ordinary camera bracket. Too small and blank areas beside an edge win in the blurred frames, which puts a halo around every hard edge. Too large and the background beside a thin object gets smeared. It is the one setting worth experimenting with, and it affects the focus stack only.
All five tools run on up to 12 frames free, at full quality — the same alignment, the same merges, the same speed, the same RAW support, and a full-resolution JPEG with no watermark. One payment of $9.99 removes the frame limit and adds the retouch brush, 16-bit TIFF and map export, and a second way of merging a focus bracket. It is one purchase, shared with your family, with no subscription and no account. If you have bought it before, "Restore a purchase" on the unlock screen will find it.
iPadOS ends apps that ask for more memory than the device can spare, and a big set of RAW frames is the one thing in this app that can get close. The title bar shows how much memory the last run actually used, so you can see how near the edge you are. If a set is too big, try fewer frames at a time, close other apps, or free some disk space — the removal tool in particular needs room on disk for every frame at once.
Frames chosen from the Files app are never copied — they stay where you keep them, and Sharp only holds a reference. If you move or delete the original, or the drive it lives on is unplugged, the frame drops out of the list. Frames from Photos are copied into the app and stay until you remove them.
No. There is no server, no analytics and no networking code of the app's own. See the privacy policy.
Write to pablinme@me.com. Tell us which tool, how many frames, what camera they came off and what you expected — and if you can, send one or two of the frames. Replies come from a person.