Astrophotography diagnosis of Soleil: Focus miss
RawFiltre Lumière Blanche Unistellar0.013328s25/11/2025 11:00
The Doc examined this image of Soleil (raw, Filtre Lumière Blanche Unistellar, 0.013328s). Estimated overall technical quality: 6/10. 1 defect found: Focus miss (severity 2/5).
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Info
- Cible
- Soleil
- Date
- 25/11/2025 11:00
- Position
- 0h00m00s · +0°00'00"
Not enough information for an opinion from the Doc.
Setup
- Type d'image
- Brut
- Télescope
- Unistellar Odyssey
- Caméra
- Unistellar Odyssey
- Filtre
- Filtre Lumière Blanche Unistellar
- Monture
- Unistellar Odyssey
- Exposition
- 0.013328s
- Phase de lune
- N/A
- Seeing
- 1.51"
- FOV
- 33.0'
The Unistellar Odyssey setup with a white-light filter is perfectly suited to the Sun: the disk fits comfortably in the 0.55 degree field, well centered, with an even black-background margin. The 0.013s exposure matches solar brightness and avoids any disk clipping, confirmed by the absence of a blown-out white plateau. To gain detail on spots and granulation, this sensor would benefit from recording a short sequence and stacking the best frames rather than relying on a single exposure. The reported 1.51" seeing is favorable, but daytime turbulence remains the limiting factor in solar imaging.
The diagnosis in detail
This is a technically sound white-light solar capture. The disk is evenly exposed with no blown-out plateau: granulation is visible near the edge and, above all, two sunspot groups stand out, a small cluster mid-left and a more developed group lower-center, confirming controlled exposure and a safe filter. No background acquisition defect applies here (no gradient, no calibration involved on a solar sub).
The only point to improve is sharpness: the spot edges are slightly soft and the photospheric granulation is not crisply resolved. On a single daytime sub this is the classic mix of slightly short focus and daytime atmospheric turbulence, which is harsh even under good reported nighttime seeing. The uniform orange cast is a cosmetic rendering of the Unistellar filter, not a color defect.
The most effective lever is not post-processing but acquisition technique: switching to short video and selecting the best frames (daytime lucky imaging) would freeze turbulence and reveal spot umbra/penumbra and granulation.
Priority actions
- Refine focus on a high-contrast sunspot group before capture
- Record a short sequence and stack the sharpest 20% of frames (lucky imaging)
- Capture during lower-turbulence hours (early morning) for better sharpness
