Astrophotography diagnosis of jupiter: Bad seeing, over-denoising and 1 other
Processed
The Doc examined this image of jupiter (processed). Estimated overall technical quality: 7/10. 3 defects found: Bad seeing (severity 2/5), Over-denoising (severity 2/5), Chromatic aberration (severity 2/5).
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Info
- Cible
- jupiter
- Position
- 6h19m60s · +20°00'00"
The last quarter Moon at 40% has no impact here: in planetary imaging exposures are in the millisecond range and the sky background is completely crushed, so lunar or urban light pollution barely matters. The real limiting factor is turbulence and Jupiter's altitude at capture time. The slightly softened limb and residual chromatic dispersion suggest the planet was not very high above the horizon. Aim for a window centred on meridian transit, watch the seeing forecasts (weak jetstream) and favour nights when the air is steady rather than transparent.
Setup
- Type d'image
- Traitée
- Phase de lune
- Dernier quartier (40 %)
- FOV
- 1.8'
The C8 with a 0.03 degree field is perfectly sized for Jupiter: the disc fills a large part of the frame without touching the edges, leaving room for derotation and final cropping. At this focal length the planetary sampling is consistent with the theoretical resolution of the 203 mm aperture, so the limit comes from the atmosphere, not the optics. To progress, adding an ADC is the most cost-effective complement for this kind of setup, followed by a high frame rate camera to multiply frames and keep only a small fraction of them.
The diagnosis in detail
The result is good for a C8: the Great Red Spot stands out clearly with its wake, the equatorial belts show festoons and irregularities, and several bright ovals are visible in the southern hemisphere. The disc geometry is correct, with no stacking distortion or obvious rotation blur, which points to a reasonably short capture sequence and clean alignment.
The three weak points are linked and largely share the same cause. Turbulence limited the available micro-contrast: the limb is softened and fine detail is smeared. To compensate, processing pushed the sharpening, which brought out a clumpy grainy texture in the bright zones and a thin dark rim at the disc edge. Finally, the planet's modest altitude leaves residual atmospheric dispersion, visible as a tint drift between the two sides of the limb, reinforced by a too-cool white balance that gives the disc a blue-grey look instead of the expected creamy tone.
None of this is crippling: these are the three classic planetary levers, and they are fixed through acquisition (altitude, ADC, frame count) far more than through processing.
Priority actions
- Capture Jupiter as close to meridian transit as possible to maximise altitude and reduce turbulence and dispersion
- Fit and tune an ADC before capture to remove the chromatic drift at the limb
- Increase frame count (longer SERs, high frame rate) and keep only the best 10-20%
- Soften the fine wavelet layers to remove the grainy texture and the edge rim
- Warm up the white balance and realign the RGB channels to recover Jupiter's creamy tone
