Because the atmosphere is steady only in brief moments. Recording thousands of short frames and keeping the small fraction taken during those moments produces detail that a single exposure could never hold. The technique is called lucky imaging.
This is the method that lets a modest telescope produce planetary images that look impossible for its aperture, and understanding it explains every specification that matters.
What the atmosphere does
Turbulence blurs and shifts the image continuously. Over a long exposure that averages into a smear. Over a few milliseconds it freezes — and occasionally it freezes at a moment when the air happened to be still.
What the software does
Ranks every frame by sharpness, discards the poor ones, aligns the rest and adds them together. The noise falls as frames accumulate, which is what allows the sharpening that brings out fine detail afterwards.
Which specification follows
Frame rate, and specifically the rate achieved over the small region of interest a planet occupies rather than the full-sensor headline. More frames in the window when the planet is well placed means more usable ones.
Why cooling barely matters here
Exposures are milliseconds long, so thermal noise has no time to build. Cooling belongs to deep-sky imaging, where exposures are minutes, and paying for it on a planetary camera buys very little.
If this page and the manufacturer’s own documentation disagree, follow the documentation. Every aperture, focal length, payload rating, field, eye relief, transmission figure and thread size on this page comes from the maker’s own published figures, with the unit as printed and the source named. None of it is measured here, and no figure is converted into another convention, because a converted number is a different number. And for any sensor: a pixel size means nothing without the focal length it sits behind. The same camera is well matched to one telescope and wasteful on another, and a frame rate quoted for the full sensor is not the rate achieved over the small region a planet occupies. This page reports the maker’s figures as published and computes no sampling from them.
The questions that keep arriving
What fraction of frames gets kept?
It depends entirely on the night. On steady air a large share is usable; on a turbulent night very few are. The software ranks them and the observer chooses a cut-off, which is why the same capture can be processed twice with different results.
Does this work for deep-sky objects?
No. Faint objects need long exposures to accumulate signal, and thousands of millisecond frames of a galaxy record almost nothing to stack. Deep-sky imaging is the opposite technique.
Last reviewed 17 September 2026