Astronomik Sulphur-II (SII) Narrowband 6nm CCD Filter (2")

Astronomik Sulphur-II (SII) Narrowband 6nm CCD Filter (2")

Due to high demand and global product shortages due to the pandemic, please call for availability.

If you have to observe from light polluted sites (like most of us), imaging with narrowband emission line filters is the best way to take great images, as all kind of light pollution can be blocked very effectively! The image(s) taken with an SII filter, when combined with images from H-Alpha and OIII filters allows you to create a final 3 channel colour Hubble palette image, just like the ones taken by the Hubble Space telescope.

The contrast between an object glowing at 672nm and the background is increased enormously.

Due to the combination of the narrow bandwidth of 6nm and the high transmission of typically 96%, the filter gives you an enormous contrast boost, as all unwanted light from wavelengths other than 672nm is blocked, from UV up to IR. This results in an extremely dark background. The FWHM of 6nm is matched to give you optimal performance with CCD and CMOS sensors with a very low dark current. The 6nm filter is the best choice if you are observing from a heavily light polluted site or if you are imaging faint objects in star-crowded regions of the Milky Way.

The lower priced 12nm filters are the right choice if you own a typical DSLR or a CCD camera with a high dark current. The 12nm filters should be the first choice for cameras with an integrated guiding sensor, as you will have about twice as much stars compared to the 6nm filter.

This filter is not for solar observation.

Price does not include shipping from Germany, which is separate from the possible free shipping from us to you. You will be notified of these shipping charges prior to payment being taken.


  • Guaranteed transmission of more than 90% at the SII line (672nm)
  • Typical Transmission of 96% at the SII Line (672 nm)
  • Full-Width-Half Maximum (FWHM): 6nm
  • Perfect blocking of unwanted light from UV up to the IR
  • parfocal with all Astronomik filters
  • MFR coating technique: usable with all optics up to f/4
  • Thickness: 1mm
  • Not sensitive to moisture, scratch resistant, non-aging
  • opticaly polished substrate, striae-free and free of residual stresses
  • High quality storage box
  • Made in Germany