Baader Filters SII CMOS Ultra-Narrowband 50x50mm (70891)

The narrowband S-II 7nm filter is designed for nebula photography, transmitting light at a wavelength of 672nm with a bandpass of 3nm. It is ideal for imaging most emission nebulae, planetary nebulae, and supernova remnants.

For those looking to replicate the iconic appearance of Hubble Space Telescope (HST) images—such as the "Pillars of Creation" in the Eagle Nebula (Messier 16)—the SII (sulfur) filter is an excellent addition to your setup after H-alpha (H-a) and OIII filters. Like the H-a filter, the SII filter operates in the deep red spectrum near 672nm. When used together, H-a, OIII, and SII filters enable tri-color narrowband imaging, creating that signature "Hubble look" for many emission nebulae. Furthermore, these filters allow imaging even under moonlit skies, ensuring your equipment remains productive rather than idle during bright lunar phases.

Specifications

• Capacity

  • Central wavelength: 671.7nm

  • Half-value width: 4nm

• Frame

  • Mount material: Aluminium

  • Coating: Reflex-Blocker™

• Compatibility

  • Suitable for systems with f/10 to f/3.5

  • Filter thickness: 2mm

  • Filter size: 50 x 50mm

• General Information

  • Type: Filters

  • Build type: Line filter

  • Series: Ultra-Narrowband

• Applications

  • Useful for photography: Yes

  • Visually useful: No

  • Twin stars: No

  • Moon & planets: No

  • Nebulae & galaxies: Yes