Skip to content

Astronomik OIII 12 nm CCD Filter - 50 mm Square - OIIICCD-50SQ

shipping truck Free shipping
SKU: ASF-OIIICCD-50SQ

Astronomik OIII 12 nm CCD Filter - 50 mm Square


  • Made especially for astrophotography, this OIII 12 nm CCD Filter from Astronomik comes in a 50 mm square format
  • Almost complete OIII line transmission
  • FWHM bandwidth of approximately 12 nm
  • The perfect filter for planetary nebulae and supernova remnant astrophotography
  • Coatings on this filter offer full resistance to the impacts of scratching, aging, and high humidity
  • This filter is diffraction limited and therefore will not reduce the optical performance of your telescope
  • Made in Germany, a country known for producing high quality optics!
  • Optimized for 6" or higher aperture telescopes


More About the Astronomik 50 mm Square OIII 12 nm CCD Filter


This Astronomik OIII CCD Filter, a narrowband emission-line filter for CCD astrophotography, features a full width at half maximum (FWHM) of 12 nm. This is optimal for use with typical CCD cameras, enabling the use of extremely fast optics. This filter permits the light of double ionized oxygen from emission nebulae pass through while blocking close to the entire rest of the spectrum in the areas where the CCD is sensitive. The aperture ratio range ideally suited for this filter is 1:3 to 1:15 with apertures above 6" (150 mm). It should also be acknowledged that Astronomik O-III CCD Filters have an up to 99% transmission, a figure that cannot be attained by stacking extra narrowband filters. An additional note on the dark current of typical CCD imagers: exposures with a CCD cooled to -15°C are constricted by the CCD's dark current, even in large metropolitan areas with a heavily illuminated background. This directly influenced the 12 nm FWHM choice. A further benefit of this 12 nm filter is the easier availability of guiding stars for cameras that have an integrated autoguider.

The contrast between OIII emission line objects and those in the background sky is greatly enhanced by this Astronomik OIII CCD Filter. It completely cuts off artificial light emissions from mercury (Hg), sodium (Na), and skyglow. Unlike with filters from other manufacturers, the Astronomik 12 nm OIII CCD Filter won't have any transmission loss or chromatic distortions unless extremely bright aperture ratios of 1:2 or more are involved. Because this filter incorporates an IR-blocker up to 1150 nm, an additional IR blocking filter is not necessary.

Employing a combination of this filter with an H-alpha or SII CCD filter allows for the production of three-color images of emission line gas nebulae, despite any heavily light-polluted environments. For this, you would need to utilize Photoshop to combine an image taken in three different wavelengths by choosing each as a separate color-channel and pasting them together. The Astronomik OIII CCD Filter is diffraction limited to preserve the optical performance of your telescope. Astronomik filters arrive with a long-lasting, high quality plastic storage container.

Transmission Specifications


  • 99+% transmission for both of the OIII lines
  • Blocks unwanted wavelengths in other areas of the visual spectrum