• DayStar Quantum Calcium II K 2 angstrom solar filter CK2AUNI ideal for serious and advanced astronomers providing a precise specialized and high performance calcium K light solar filter solution for seeing fine solar surface detail chromospheric network calcium bright points solar plage regions and solar activity in unique and scientifically rich calcium K light for advanced sun viewing and solar photography — Telescope Wolves
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Daystar

DayStar Quantum Calcium II K-Line 2Å Solar Filter — Reveal Solar Active Regions and Chromospheric Detail in Calcium Light

DayStar Quantum Calcium II K-Line 2Å Solar Filter — Reveal Solar Active Regions and Chromospheric Detail in Calcium Light

$17,990.00
$17,990.00
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The calcium K line at 393.4nm is one of the most scientifically productive solar wavelengths — used by professional observatories from Meudon to BBSO for chromospheric mapping and network studies since the 19th century. The DayStar Quantum 2Å Ca II K filter resolves chromospheric structures including the network, plage regions, and active region dynamics with outstanding clarity. At 2Å, this filter delivers meaningful contrast over the photospheric background while preserving chromospheric signal, making it suitable for high-resolution imaging programs. Note: requires telescope optics with good near-UV transmission. ERF required. Ships free to the US.

Specifications
SKU CK2AUNI
Wavelength Ca II K-line (393.4nm)
Filter Type Fabry-Pérot etalon (electrically heated for thermal stability, electronically tunable)
Bandpass (FWHM) 2Å — higher contrast than Ca II H 5Å; chromospheric network and plage structure clearly resolved
Best For Chromospheric network, plage and active region detail, multi-wavelength solar programs, high-resolution Ca II imaging
Wavelength Display Live LCD readout, accurate to 0.1Å
Tuning Electronic wavelength control
Power 12VDC (100–240VAC supply included with US, EU, UK, and AU adapters)
UV Transmission Note Telescope optics must transmit at 393.4nm; cemented objectives and many achromats attenuate near-UV significantly
ERF Required Yes — front-mount Energy Rejection Filter required; sold separately
What's in the Box Quantum Ca II K-Line 2Å filter, 100–240VAC power supply with international adapters (US, EU, UK, AU)
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Frequently Asked Questions

With a beginner telescope you can see a surprising amount — the craters and mountains on the Moon, the rings of Saturn, the moons of Jupiter, and star clusters like the Pleiades. As you get more comfortable, you can also spot nebulae and distant galaxies. Not sure which beginner telescope is right for you? Check out our Telescope Buying Guide.
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