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Astronomik OIII 12 nm CCD Filter - T-Mount - OIIICCD-T

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SKU: ASF-OIIICCD-T

Astronomik OIII 12 nm CCD Filter - T-Mount


  • This 12 nm OIII CCD Filter from Astronomik is designed specifically for astrophotography and comes in a round, T-thread mount
  • Almost 100% transmission in the OIII line
  • 12 nm FWHM bandwidth
  • The perfect filter for photographing planetary nebulae and leftover supernova vestiges
  • Coatings protect amazingly well against scratching, aging, and humidity
  • This filter is diffraction limited and thus will not compromise your telescope's optical performance level
  • Made in Germany, a country with a reputation for producing high quality optics
  • Works best for telescopes with 6" aperture or more


More About the Astronomik T-Mount OIII 12 nm CCD Filter


This Astronomik OIII CCD Filter is a narrowband emission-line filter, expressly designed for CCD astrophotography, with a 12 nm FWHM. It lets double ionized oxygen from emission nebulae pass through while, at the same time, blocking nearly 100% of the remaining spectral areas where the CCD is more vulnerable. The 12 nm full width at half maximum (FWHM) allows for extremely fast optics to be used with common CCD cameras. For telescopes with apertures over 6" (150 mm), 1:3 to 1:15 is the ideal focal ratio range. It should also be acknowledged that this filter's transmission of up to 99% cannot be achieved by stacking extra narrowband filters. Furthermore, with regards to the dark current of typical CCD cameras, exposures with a CCD cooled to -15°C are limited by the dark current of the CCD, even in large cities with strongly illuminated backgrounds. This led directly to the 12 nm selection. Another benefit of this filter is the increased opportunity for finding guide stars with imagers 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.

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


  • 99%+ transmission for each of the OIII lines
  • Obstructs unnecessary wavelengths from other areas of the visual spectrum