The Astronomik SII 12nm MaxFR Clip-Filter EOS R APS-C (Astronomik, SKU: 10220224 / 8h11vu) is a narrowband emission filter designed for Canon EOS R APS-C mirrorless cameras. This model was developed for imaging nebulae emitting sulfur light in the SII 671.7 nm and 673.0 nm lines, both under light-polluted skies and at dark observing sites. The version with MaxFR coating was optimized for use with very fast optical systems, which means the filter can also be used with instruments of very low focal ratio without the need for separate high-speed versions. The 12 nm Full Width Half Maximum bandwidth also makes the filter well suited to cameras with integrated guiding sensors or systems where a larger number of visible guide stars is important.

Key features

• narrowband SII filter for Canon EOS R APS-C cameras
• designed for imaging sulfur-emission nebulae
• 12 nm Full Width Half Maximum bandwidth
• high image contrast thanks to effective suppression of the sky background
• blocking of unwanted light outside the SII lines from UV to IR
• MaxFR coating for use with very fast optical systems
• full usability in the focal ratio range from f/1.7 to f/6
• approximately 85% of maximum transmission at f/1.4
• high transmission at the SII 671.7 nm and 673.0 nm lines
• good visibility of guide stars compared to narrower filters
• parfocal with other Astronomik filters

Box contents

• Astronomik SII 12nm MaxFR Clip-Filter EOS R APS-C
• filter storage box

Technical specifications

• manufacturer: Astronomik
• product name: SII 12nm MaxFR Clip-Filter EOS R APS-C
• SKU: 10220224 / 8h11vu
• intended use: imaging sulfur-emission nebulae
• camera compatibility: Canon EOS R7, Canon EOS R10, Canon EOS R50, Canon EOS R50 V, Canon EOS R100
• non-compatible lenses: Canon RF 14mm f/1.4 L VCM, Canon RF 28mm F2.8 STM, Canon RF 35mm F1.8 IS Macro STM, Canon RF 85mm F1.2L USM, Canon Extender RF 2x, Canon Extender RF 1.4x
• guaranteed transmission: more than 90% at both SII lines 671.7 nm and 673.0 nm
• typical transmission: 96% at both SII lines
• FWHM: 12 nm
• coating: Astronomik MaxFR
• recommended focal ratio range: from f/1.7 to f/6
• transmission at f/1.4: approximately 85% of maximum transmission
• glass thickness: 1 mm
• parfocality: yes, with other Astronomik filters
• optical quality: diffraction-limited
• coating resistance: highly resistant to scratches, humidity, and aging
• country of manufacture: Germany