Astronomik H-alpha 12nm XT Clip-Filter EOS R XL (Astronomik, SKU: 10212090 / 8h11gj) is a narrowband emission line filter designed for imaging hydrogen nebulae. It significantly increases the contrast between objects emitting at the H-alpha line (656nm) and the sky background, enabling detailed imaging both from light-polluted and dark observing sites.

Key features

• 12nm narrowband H-alpha filter
• maximizes contrast at 656nm
• effectively blocks sodium (Na) and mercury (Hg) vapor lamp emissions, natural airglow and most moonlight
• blocks unwanted radiation outside 656nm from UV to IR
• especially suitable for DSLR cameras with CMOS sensors and CCD cameras with normal or high dark current
• preferred for cameras with integrated guiding sensors (more guide stars compared to 6nm version)
• XT version optimized for astrophotography with wide-angle lenses
• extremely thin substrate (0.3mm or 0.5mm) reducing corner image distortion
• Astronomik MFR coating providing excellent out-of-band blocking and no halos
• parfocal with other Astronomik filters
• diffraction-limited design – no loss of resolution or contrast
• strict quality control before shipment

Box contents

• Astronomik H-alpha 12nm XT Clip-Filter EOS R XL
• high-quality, durable filter storage box

Technical specifications

• spectral line: H-alpha (656nm)
• bandwidth (FWHM): 12nm
• guaranteed transmission >90% at 656nm
• typical transmission 96% at 656nm
• recommended focal ratio range (MFR): f/3 to f/∞
• glass thickness: 1mm (XT: 0.3mm or 0.5mm)
• finely polished optical glass free from streaks, internal stress and bubbles
• coating: Astronomik MFR
• fully resistant to high humidity and aging effects

The Astronomik H-alpha 12nm filter enables high-contrast imaging of red emission nebulae even under heavy light pollution. The filter must not be used for solar observation.