Astrophotography diagnosis of Lune: Bad seeing
Processedircut
The Doc examined this image of Lune (processed, ircut). Estimated overall technical quality: 6/10. 1 defect found: Bad seeing (severity 2/5).
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Info
- Cible
- Lune
- Site
- Bortle 5 · banlieue résidentielle (VIIRS)
Waxing gibbous at 61%: the Moon is the target itself, so illumination and Bortle 5 have no negative impact here, lunar imaging is immune to light pollution and moonlight. The limiting factor is not the sky background but atmospheric seeing and the Moon's altitude. Shoot the Moon as high as possible in its path to cross less atmosphere, and favor nights of good seeing (weak jet stream) over merely transparent ones.
Setup
- Type d'image
- Traitée
- Télescope
- C11
- Caméra
- asi585mc
- Filtre
- ircut
- Monture
- eq6r pro
- Phase de lune
- Gibbeuse croissante (61 %)
The C11 (2800 mm) and ASI585MC (2.9 µm pixels) sample very finely, ideal for detailing a terminator sector like this. At this focal length seeing caps resolution well before the optics: turbulence, not gear, is the limiter. The IRcut filter is sensible on a color sensor to avoid IR bloat. On an EQ6-R Pro, tracking is more than enough for short planetary/lunar video. The setup is perfectly matched to the target; the challenge is purely capture and processing.
The diagnosis in detail
The image shows the terminator across the Apennine basin, with Archimedes (the large flat-floored crater at center) and the Autolycus/Aristillus pair lit by grazing light that emphasizes relief. The composition works and the shadow contrast is pleasant, deliberately using the unlit part of the disk.
The weak point is resolution: at 2800 mm the C11 can deliver far more detail than shown here. Crater rims and mare wrinkle ridges look softened, the classic signature of atmospheric turbulence averaging the high frequencies during capture. This is not an optics fault or a clear focus miss, but a ceiling imposed by seeing and, possibly, too permissive frame selection at stacking.
Secondarily, the color balance leans warm sepia. The lunar surface is nearly neutral: a white-balance correction (or going monochrome) will give a more natural look. The main gain will come from high-frame-rate video capture followed by strict best-frame selection (lucky imaging) and measured wavelet sharpening.
Priority actions
- Switch to high-frame-rate video capture and stack only the best 5-20% of frames (AutoStakkert!3) to beat turbulence
- Acclimate the C11 before the session and shoot the Moon as high as possible above the horizon
- Sharpen with wavelets (RegiStax/AstroSurface) without creating over-sharpen halos
- Rebalance whites to remove the sepia cast and recover a neutral lunar grey
