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Astronomik OIII 12 nm CCD Filter - 2" Round Mounted - OIIICCD-2

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SKU: ASF-OIIICCD-2

Astronomik OIII 12 nm CCD Filter - 2" Round Mounted


  • The Astronomik 2" Round Mounted OIII 12 nm CCD Filter is expressly designed for astrophotography
  • Almost 100% transmission in the OIII line
  • Approx. 12 nm FWHM bandwidth
  • The optimal filter for photographing planetary nebulae and supernova remnants
  • Coatings shield incredibly well against scratching, aging, and humidity
  • Diffraction limited, this filter will not lessen your telescope's optical performance
  • Made in Germany, a country renowned for producing high quality optics!
  • The Astronomik OIII filter is ideally suited for telescopes with at least 6" aperture


More About the Astronomik 2" OIII 12 nm CCD Filter


The Astronomik OIII CCD filter is a narrow band emission-line-filter for CCD photography. The filter lets the light of double ionized Oxygen of emission nebulae pass and blocks nearly the whole remainder of the spectrum where the CCD is sensitive. The full width at half maximum (FWHM) of 12 nm is ideal for common CCD cameras and allows the use of very fast optics. The optimal aperture ratio for the use of the filter is 1:3 to 1:15 with apertures of more than 6" (150 mm). It should be noted that the filter has a transmission of up to 99%, which cannot be attained by stacking more narrow-band filters. A further note, which led to selecting the half width (FWHM), is the dark current of common CCD imagers. Exposures with a CCD cooled to -15°C are limited by the dark current of the CCD, even in large cities with a bright background. Another advantage of the 12 nm filter is the better availability of guiding stars for cameras with built-in-autoguider.

The Astronomik OIII CCD Filter enhances the contrast between objects, in this instance between objects in the OIII emission line and the background sky. This filter offers total suppression of emission lines from artificial lighting sources such as mercury (Hg), sodium (Na), and airglow. Transmission deficits and chromatic distortions, which can occur when filters from other brands are used, only happen with Astronomik filters when exceptionally bright aperture ratios of 1:2 and above are involved. As this filter incorporates an IR-blocker up to 1150 nm, a supplementary IR blocking filter is not necessary.

When using the Astronomik OIII CCD filter together with the H-alpha and SII CCD filters you can obtain three-color images of emission line objects (gas nebulae) from locations with very strong light pollution. To do so, you would take an image in three different wavelengths, select each one as a color-channel in Photoshop and paste them together as one single color image. Diffraction limited, the filter will not reduce the optical performance of your telescope! Astronomik filters are delivered in a high-quality, long lasting, plastic filter box.

Transmission Specifications


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