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Astronomik OIII 12 nm CCD Filter - 1.25" Round Mounted - OIIICCD-1

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SKU: ASF-OIIICCD-1

Astronomik OIII 12 nm CCD Filter - 1.25" Round Mounted


  • The Astronomik OIII 12 nm CCD Filter is mounted in a round, 1.25" cell and is made specifically for astrophotography
  • This filter has a transmission close to 100% in the OIII line
  • FWHM bandwidth of roughly 12 nm
  • The perfect filter for imaging planetary nebulae and supernova vestiges
  • Coatings offer remarkable protection from the effects of scratching, aging, and humidity
  • Diffraction limited, the filter will not reduce the quality of your telescope's optical performance
  • German-made for excellent optical quality!
  • The Astronomik OIII Visual Filter works best with telescopes that have a minimum of 6" aperture


More About the Astronomik 1.25" OIII 12 nm CCD Filter


This Astronomik OIII CCD Filter is a narrowband emission line filter designed for CCD imaging. It allows light from double ionized oxygen of emission nebulae to pass through while simultaneously blocking almost the entire remainder of the spectrum where the CCD is sensitive. The 12 nm full width and half maximum (FWHM) enables the use of very fast optics and is optimal for typical CCD cameras. With instruments that have apertures of more than 6" (150 mm), the ideal aperture ratio for the use of this filter is 1:3 to 1:15. It should be acknowledged that this filter has an up to 99% transmission, which is impossible to achieve by stacking more narrowband filters. Furthermore, a note on the dark current of typical CCD imagers. Exposures with a CCD cooled to -15ºC are restricted by the CCD's dark current, even in big metropolitan areas with a bright background. This lead to the 12 nm FWHM selection. An additional advantage of this 12 nm filter is the enhanced availability of guiding stars for cameras with an incorporated autoguider.

Highlighting the contrast between objects in the OIII emission line and objects in the skyglow background, the Astronomik OIII CCD Filter completely eliminates artificial light sources such as mercury (Hg) and sodium (Na) from street lamps. With the exception of extremely bright aperture ratios of 1:2 or more, transmission losses and chromatic distortions are not a problem, unlike with filters from other brands. Since this filter has an integrated IR-blocker up to 1150 nm, you won't need a supplementary IR-blocker to go with it.

When employing the Astronomik OIII 12 nm CCD Filter in conjunction with an H-Alpha or SII CCD filter, even imaging in an environment with very heavy light pollution will not prevent you from obtaining three-color images of emission line gas nebulae. To accomplish this, you need to capture an image in three different wavelengths, choose each as a color-channel in Photoshop and paste them together as one individual color image. This filter is diffraction limited and will not lower the optical efficiency of your telescope! Astronomik filters arrive with a long-lasting plastic storage box of supreme quality.

Transmission Specifications


  • Above 99% transmission for each of the OIII lines
  • Blocks superfluous wavelengths of other visual spectral areas