Solar Imaging

White Light

The entry point for solar imaging and the most affordable place to start. A white light filter — typically Baader AstroSolar safety film — blocks 99.999% of sunlight to reveal the Sun's photosphere. You'll see sunspots, the granular texture of the solar surface, and bright faculae around active regions. The film costs around £20 for an A4 sheet and can be made into a DIY filter housing with cardboard and tape. A Herschel Wedge offers superior quality for refractor users. Always fit the filter to the front of the telescope — never the eyepiece end.

What you'll see: Sunspots, granulation, faculae, limb darkening. Good for: Beginners; any telescope type; low cost

Hydrogen Alpha (Hα)

Where solar imaging becomes truly spectacular. Ha filters are tuned to 656.28nm — the wavelength emitted by hydrogen gas in the Sun's chromosphere — revealing features completely invisible in white light. Prominences arch dramatically from the solar limb, dark filaments snake across the disc, and bright plages surround active regions. Features can change noticeably within minutes. Dedicated Ha telescopes from Coronado and Lunt are the most convenient route, with the Coronado PST a popular entry-level choice. The DayStar Quark fits a refractor. A monochrome camera gives best results.

What you'll see: Prominences, filaments, flares, plages, chromospheric detail. Good for: The wow factor; dynamic, fast-changing features.

Calcium K (CaK)

A specialist imaging-only filter working at 393.4nm — at the very edge of the visible spectrum. CaK reveals the chromospheric network spread across the entire solar surface, with magnetically active regions glowing brightly and sunspot plages showing exceptional clarity. The resulting images have a striking blue-violet tone quite unlike any other solar view. Because our eyes have very poor sensitivity at this wavelength, a camera is essential — a monochrome sensor gives significantly better results. A primary solar filter (Herschel Wedge or AstroSolar film) must always be used alongside the CaK filter.

What you'll see: Chromospheric network, plages, supergranulation, magnetic active regions. Good for: Experienced imagers; monochrome cameras.

Magnesium (Mg)

The most unusual of the solar filter types, the Magnesium Ib2 filter works at around 517nm — probing a layer of the solar atmosphere between the photosphere and chromosphere that no other filter quite reaches. It reveals a unique mix: plages similar to those seen in CaK, granulation detail, filament outlines from Ha, and structure in highly magnetised regions not visible in any other wavelength. The DayStar Quark Magnesium is currently the main consumer option. Recommended for those who already image in white light and Ha and want to explore the Sun's atmosphere in greater depth.

What you'll see: Inter-atmospheric detail, magnetised regions, plages, filament outlines. Good for: Advanced imagers wanting to go beyond Ha.