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Astronomik SII 6 nm CCD Filter - T-Mount - SII6-T

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SKU: ASF-SII6-T

Astronomik SII 6 nm CCD Filter - T-Mount


  • Mounted in a round, t-threaded cell, this Astronomik SII 6 nm CCD Filter has been designed especially for astro-imaging applications
  • Designed to the highest technical standards to enable the optical performance required for deep sky imaging with CCD cameras
  • Ionized sulfur (SII) light is allowed to pass while the complete rest of the visual spectrum as well as IR is cut off
  • Nearly 6 nm FWHM bandwidth
  • Optimal for imaging planetary nebulae and supernova vestiges
  • German-made for high optical quality!


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


For CCD astrophotography operations, this SII 6 nm CCD T-Mount Filter from Astronomik is the ideal narrowband filter. It has a smaller full width at half maximum (FWHM) of 6 nm to enable higher contrast gain than you would get from the 12 nm filter when also factoring in a typical 96% transmission given that all unwanted light from alternate wavelengths from UV up to IR is blocked. This results in an especially dark background. While you may experience transmission reductions and chromatic distortions with other filters, these only occur with Astronomik filters when exceptionally bright 1:2 and above aperture ratios are involved.

CCD filters from Astronomik highlight the contrast between objects. The SII filter highlights the contrast between ionized sulfur (SII) emission line objects and the skyglow background. Plus, this filter also completely obstructs artifical light sources such as mercury (Hg), sodium (Na), and skyglow, making it an excellent filter for use in heavily light polluted conditions. A superior quality substrate allows the Astronomik SII 6 nm CCD Filter to provide the same needle sharp star views you would see with your normal telescope.

Complete occlusion of undesired visible and IR band spectral wavelengths is enabled by this Astronomik SII 6 nm T-Thread CCD Filter. Parfocal with all other filters produced by Astronomik and diffraction limited to maintain your telescope's optical performance. Coatings offer strong protection from scratching as well as the impacts of aging and high humidity. This filter is shipped in a durable plastic filter container of superior quality.

Transmission Specifications


  • Typical transmission of 96% in the SII (672 nm) line
  • Offers total blockage of undesired light from UV up to IR