Diagnose 07 of 29 Acquisition quality
One side soft
One edge or one corner is consistently worse than the rest of the frame, and the others are fine.
- At 100 %
Compare each corner with the one diagonally opposite. A soft or stretched corner whose opposite is sharp is tilt or sag.
- Causes, most likely first
Sensor tilt
The sensor is not square to the light path, so one side sits inside focus and the other outside it.
FixRule out spacing first, since spacing errors are symmetric. Then correct the tilt with the camera's tilt adjuster if it has one.
Loose adapter
A loose adapter lets the camera sit at a slight angle, and the angle can change as the scope points somewhere else.
FixTighten every threaded joint and clamp in the train, then take a new frame.
Sagging focuser drawtube
A drawtube that sags under the weight of the camera tips the whole train.
FixAdjust the focuser's tension and lock it once focused. If it still sags, take weight off it; a stiffer focuser is the gear fix.
- Looks like, but isn't
Spacing errors are symmetric, with all four corners about equally bad. Tilt favors one side.
Guiding and balance problems stretch stars the same way everywhere, the center included.
- One frame can't tell you
One frame shows which side is worse. Whether it is fixed tilt or something loose needs a second frame with the scope pointed somewhere else.
- How to confirm the fix
Opposite corners that match in a focused sub, at more than one pointing position.
- Sources
No outside source is cited here. The signature, the causes and their order are the atlas’s own, from imaging experience. The order is a judgment of likelihood; no measured frequency is behind it.
In the symptom picker
- Stars are worse on one side, or in one corner, and fine elsewhereweight 3
Tools for this
Last updated All 29 failure modes, and the symptom picker