SII 7nm Pegasus filter - 2″ mounted

Pegasus Astro SII filter (Sulfur II)

The filter Pegasus Astro SII is a high-quality narrow-band filter designed for astrophotography. Here are its detailed features:

Technical specifications

• Diameter : 50.8 mm (2 inches)
• Thread : M48 x 0.75 mm
• Total thickness : 7.5 mm (5 mm filter body + 2.5 mm thread)
• Glass thickness : 2 mm
• Bandwidth : 7 nm
• Central wavelength : 672 nm
• Transmission : Tave > 80% at 672 nm
• Polishing : 1/4 wavelength
• Coating : Anti-reflective multilayer
• Type : Narrow-band interference filter

Features and benefits

• Optimum transmission : The filter offers transmission greater than 80% at the central wavelength of 672 nm, corresponding to the emission lines of doubly ionized sulfur (SII).
• Narrow bandwidth : With a bandwidth of just 7 nm, this filter effectively isolates SII emission lines, enabling excellent separation of spectral details.
• Parafocality: The SII filter is parafocal with other Pegasus filters, simplifying the image acquisition process.
• Superior optical quality : The 1/4-wavelength polish guarantees excellent image quality and optimum sharpness.
• Anti-reflective coating : Multi-layer anti-reflective coating eliminates halos, ghosting and unwanted reflections.
• Durability: The filter is designed to withstand scratches and temperature changes.
• UV and IR blocking : The filter effectively blocks UV and IR wavelengths, improving image sharpness and reducing halos.

Astrophotography applications

• Nebula imaging : Ideal for capturing the details of nebulae rich in ionized sulfur.
• Reducing light pollution : Its narrow bandwidth enables effective imaging even in areas of high light pollution or under a full moon.
• False color imaging : Used in the Hubble palette technique (SHO) to create spectacular false-color images.
• High-resolution imaging : The narrow bandwidth enables high-contrast images to be obtained, revealing fine details in nebular structures.