Skip to content

Astronomik SII 6 nm CCD Filter - 50 mm Round - SII6-50R

shipping truck Free shipping
SKU: ASF-SII6-50R

Astronomik SII 6 nm CCD Filter - 50 mm Round


  • This round 50 mm threaded cell formatted Astronomik SII 6 nm CCD Filter has been designed for the specific purpose of CCD astrophotography
  • Made with the highest technical standards in mind to enable peak optical performance for deep sky imaging applications with your CCD camera
  • Allows ionized sulfur (SII) light to pass through while completely cutting off the remainder of the visual spectrum plus IR
  • Approximate FWHM bandwidth of 6 nm
  • Ideally suited for planetary nebulae and supernova remnant imaging
  • Made in Germany, a country recognized for producing high quality optics!


More About the Astronomik 50 mm Round SII 6 nm CCD Filter


The Astronomik 50 mm Round SII 6 nm CCD Filter is the optimal narrowband filter for CCD astrophotography applications. Features a reduced 6 nm FWHM (full width at half maximum) combined with a typical 96% transmission for an incredible contrast enhancement since all spurious light from wavelengths other than the SII line (672 nm) is cut off from UV up to the IR. This provides a background that is extremely dark. Transmission losses and chromatic distortions, while an issue with other filters, only arise with Astronomik filters when especially bright aperture ratios of 1:2 or more come into play.

Astronomik SII CCD filters enhance the contrast between objects, in this case between objects in the ionized sulfur (SII) emission line and the background sky. Also optimal for combating light pollution, this filter blocks artificial light from sources such as mercury and sodium-vapor street lamps, common light pollution culprits. The supreme quality of the Astronomik SII 6 nm CCD substrate allows you to observe the same razor sharp stars you would typically see from your normal telescope.

All superfluous wavelengths in the visible and IR bands of the spectrum are completely obstructed with the Astronomik 50 mm SII 6 nm CCD Filter. Parfocal with all other Astronomik filters and diffraction limited to keep the optical performance of your telescope from degrading. The coatings on this filter provide remarkable protection from scratching as well as high humidity and aging effects. The Astronomik 50 mm SII 6 nm Filter is delivered in a durable, high-quality plastic filter case.

Transmission Specifications


  • Typical 96% transmission in the SII (672 nm) line
  • Provides complete obstruction of unwanted light from UV up to IR