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Astronomik SII 12 nm CCD Filter - 50 mm Round - SII-50R

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SKU: ASF-SII-50R

Astronomik SII 12 nm CCD Filter - 50 mm Round


  • The Astronomik SII CCD Filter is a photographic filter and comes in a thin, 50 mm round threaded cell
  • By designing the SII 12 nm CCD Filter with regards to peak technical standards, Astronomik has created a filter that provides the optical performance you seek for deep sky CCD imaging applications
  • Allows ionized sulfur (SII) light to pass while blocking almost the entire remainder of the visual spectrum along with IR
  • This Astronomik SII CCD Filter has a FWHM of about 12 nm
  • An ideal filter for planetary nebulae and supernovae remnant imaging
  • Made in Germany, a country recognized for producing high quality optics!


More About the Astronomik 50 mm Round SII 12 nm CCD Filter


For CCD astrophotography applications, you would be hard pressed to find a more ideal narrowband filter than the Astronomik SII 12 nm CCD Filter. Its 12 nm FWHM (full width at half maximum) is optimal for standard CCD cameras, enabling the use of extremely fast optics. The f/number application range spans from 1:2.8 to 1:15. Transmission reductions and chromatic aberrations, sometimes an issue with other filters, only arise with Astronomik filters when severely bright 1:2 and more aperture ratios are involved. A further advantage of 12 nm filters is the improved availability of guide stars for cameras featuring a built-in autoguider. Up to 99% transmission.

The Astronomik SII CCD filter increases the contrast between objects, in this case between those with SII emission lines and the skyglow background. Also, our Astronomik SII-CCD filter completely suppresses the emission lines of artificial lighting (mercury (Hg) and sodium (Na) and skyglow, making it a great light pollution filter! Due to the high optical quality of the Astronomik CCD SII substrate you will see the same needle-sharp stars as you would from your normal telescope.

All undesired wavelengths in the visible and IR spectral bands are completely obstructed with the Astronomik 50 mm Round SII 12 nm CCD Filter. Parfocal with all other filters from Astronomik, the SII-50R has an ultra thin substrate, and is diffraction limited to maintain the optical efficiency of your telescope. Coatings provide total resistance to blemishes caused by scratching, aging, and high humidity. This Astronomik filter arrives in a durable plastic filter case of superior quality.

Transmission Specifications


  • 97%+ ionized sulfur (SII) line transmission
  • Blocks almost the entire remainder of the visual spectrum
  • Blocks unwanted infrared wavelengths