SharpStacker — Support
Astrophotography stacking for iPhone, iPad and Mac.
When reporting a problem, please include your device and OS version, the SharpStacker
version, a short description, and a screenshot if you can. Sample RAW shots may help —
since they're large, share a link instead of attaching them.
Frequently asked questions
- What does SharpStacker do?
- It aligns and stacks many night-sky RAW exposures into a single cleaner, more detailed
image. The more frames you stack, the lower the noise — it drops roughly with the square
root of the number of frames.
- How should I shoot for stacking?
- Use a tripod and keep the framing identical across every frame. Shoot fully manual with
fixed settings (same aperture, shutter speed and ISO) and lock focus and white balance. Take
a burst of many frames. Keep each exposure short enough to avoid star trails — as a rule of
thumb, 500 ÷ focal length (mm) gives the longest exposure in seconds on full frame.
- Which files can I import?
- Only RAW files.
- Which stacking mode should I choose?
-
- Average — smoothest noise reduction on a clean sky (at least 2 frames).
- Median — removes plane and satellite trails, passers-by and hot pixels (at least 3 frames).
- Sigma Clipping — rejects outliers then averages; a solid default (at least 3 frames).
- What is the sky mask for?
- It's only needed when your shot has a fixed foreground (landscape, buildings, subjects)
while the sky rotates: it separates sky from foreground. Generate it automatically or paint
it by hand. For pure-sky frames you can skip this step.
- What format is the exported image?
- A 16-bit TIFF, ready for curves and color grading in your favourite editor.
- Are my photos uploaded anywhere?
- No. All processing happens on your device — your photos never leave it.