| Feature / Aspect | Sol’Ex (Solar Explorer) | Star’Ex (Stellar Explorer) |
|---|---|---|
| Primary Use | Solar spectroscopy & imaging | Stellar and deep-sky spectroscopy |
| Light Source | Sun (bright, extended source) | Stars, nebulae, galaxies (faint, point sources) |
| Telescope Type | Small refractors (e.g., 60–80mm) | Medium scopes (e.g., 80–120mm refractors, SCTs) |
| Diffraction Grating | Typically 2400 lines/mm | 1200–1800 lines/mm (better for faint targets) |
| Slit Design | Fixed narrow slit | Micrometric adjustable slit (optional upgrade) |
| Field of View | Wide enough to scan solar disk | Very narrow—star must be precisely centered |
| Mount Requirements | Tracking optional for scan; solar mount helpful | Tracking required; guiding strongly recommended |
| Exposure Time | Fractions of a second | Long exposures (10s of seconds to minutes) |
| Image Target Size | Full-disk or region-of-interest solar scans | Point sources (stars), line profiles from nebulae |
| Recommended Camera | Mono planetary/astro cam (e.g., ASI178MM) | Same, or more sensitive mono cams for low light |
| Scan Method | Mechanical solar disk scanning | Fixed star guiding; no scanning |
| Processing Software | IRIS + custom tools (Christian Buil scripts) | Same as Sol’Ex (IRIS, ISIS, etc.) |
| Modularity | Swappable optics & 3D printed | Shares design roots with Sol’Ex; interchangeable parts |
| Power Level / Safety | Requires solar filter (Herschel wedge or ERF) | Standard nighttime safety |
| Shelyak Kit Availability | Yes – optical kit available | Yes – optical kit available |
| 3D Files Provided By | Christian Buil via SpectroLab | Same site—Star’Ex files also available |
| Cost (approx) | ~$300–$400 (kit + printed parts) | ~$400–$500 (kit + printed parts + guiding setup) |
| Skill Level | Intermediate | Intermediate to advanced |
Shelyak Sol'Ex
The Sol'Ex is a compact spectrograph kit designed for solar spectroscopy and imaging. It’s an educational and scientific tool that lets you observe the solar spectrum in detail, including features like prominences, sunspots, granulation, and chromospheric layers like H-alpha and Ca II. This system was developed by Christian Buil, the renowned French astronomer who was among the first to use a CCD device as an amateur astronomer and, as an author and the developer of IRIS, became an essential resource for other amateurs experimenting with CCD cameras.
The Sol'Ex is a transmission grating spectrograph designed to be 3D printed and assembled. Shelyak provides the most difficult to produce and high precision pieces and you do the rest. Intended to be accessible, affordable, and easy to build and is a great beginner friendly entry to solar spectroscopy.
What's Included
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Collimation lens
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Camera lens
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Diffraction grating (typically 2400 lines/mm)
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Slit
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Threaded holders and adapters for 3D-printed housing
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Optional: Fabry-Perot etalon for more advanced imaging
What Can You Do With It?
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Observe chromospheric features using narrow-band imaging (like H-alpha).
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Map velocity fields using Doppler shifts (e.g., in prominences).
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Create full-disk solar images by scanning across the Sun and stitching the data.
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Record changes in solar activity over time with very high detail.
Good to Know
- Will work best with 60-80mm refractors.
- Don't forget a tracking mount for consistent results
- Detailed instructions are included so you can 3D print your own housing. Don't have your own 3D printer? Check your local library, many offer 3D printer time for a low fee.
Star'Ex
The nightime counterpart to the Sol'Ex, the Star'Ex is designed for stellar and deep-sky spectroscopy with the same principles of accesiblity and build it yourself in mind.
What's Included
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A collimator lens (optimized for f/4 or f/5)
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A camera lens (for the spectrograph's imaging path)
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A diffraction grating, usually 1200 lines/mm or 1800 lines/mm (depending on resolution goals)
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A micrometric slit system (optional but great for precision)
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Specialized mounts and hardware for integrating with the 3D-printed body
What Can You Do With It?
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Classify stars (spectral type, temperature, luminosity class)
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Measure Doppler shifts (to detect stellar motion or binary systems)
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Analyze emission and absorption lines from nebulae and novae
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Compare spectra across different objects (great for citizen science and educational work)
Good To Know
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Best with medium focal length telescopes like 80–120mm refractors or 6–10" SCTs.
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Must be used on a motorized equatorial mount - guiding is crucial.
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Pairs well with mono astronomy cameras and guiding setups (e.g., a ZWO ASI178MM for imaging + a ZWO mini guide cam).
