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Astronomik UHC Filter - 31 mm Round - UHC-31

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SKU: ASF-UHC-31

Astronomik UHC Filter - 31 mm Round


  • This Astronomik 31 mm machined cell UHC Filter is a great visual filter designed for broadband deep sky observing
  • Made with the highest technical standards in mind to supply the high optical efficiency you want and need for viewing deep sky objects
  • Due to an almost complete transmission of H-Beta and O-III emission lines, more gas and planetary nebulae detail will become apparent
  • All Astronomik filters feature multi-layer coatings to insulate them from scratching and aging effects, as well as high humidity
  • Made in Germany, a country renowned for their high optical quality!


More About the Astronomik 31 mm Round UHC Filter


Designed for visual deep sky observation, the Astronomik UHC Filter allows nearly 100% of H-beta and O-III lines to get through, while blocking scattered light from other wavelengths. Plus, a second bandpass for the H-alpha line ensures it also reaches the eye. Because of the strong reduction of the sky background, gas and planetary nebulae are visible with a surprising abundance of detail. The Astronomik UHC Filter offers sufficient light for satisfactory observing of deep sky objects with smaller telescopes thanks to its high transmission.

This filter works best with telescopes featuring focal ratios between f/4 and f/15. Loss of transmission and color displacement, which can be a problem with other filters on the market, only crop up with Astronomik filters when ultra fast focal ratios of f/3 or less are in play. Astronomik UHC filters work with 2" aperture instruments and above, but work particularly well with 5" apertures and larger. When measured against other available filters, the Astronomik UHC filter displays more stars along with more nebula characteristics, and due to the high quality of the glass, you will be able to view stars as tiny pinpoints.

With fully sealed coatings, the Astronomik UHC Filter is unaffected by external moisture. These filters maintain their transmission characteristics indefinitely. In order to obtain even the finest of scratches, you would have to deliberately rub these ultra tough coatings with sandpaper! Scratching them by accident would be impossible. The Astronomik UHC Filter comes with a durable, high-quality plastic storage case.

Transmission Specifications

  • 99+% transmission at 486 nm (H-beta)
  • 99+% transmission at 496 nm (OIII)
  • 99+% transmission at 501 nm (OIII)
  • 96% transmission at 656 nm (H alpha)
  • Obstructs unwanted wavelengths