Addendum - Optical Filter

Omegon ClearSky Filter

updated: 2021-08-15

The night is never completely dark. It is brightened by artificial lighting and so-called airglow. This is a glow in the upper atmosphere caused by UV and X-rays coming from the sun. This glow is irritating when observing with a telescope. The Omegon Clear Sky filter blocks the relevant wavelengths, thus increasing contrast during observing. The filter also blocks most of the artificial lighting and stray light that unnecessarily interfere with your observing.

The Clear Sky filter is ideal for small to medium-sized telescopes up to about 150mm in aperture. Its use is very straightforward - simply screw it into the 1.25" filter thread of your 1.25" eyepiece. Hey presto, the sky darkens and astronomical objects become clearer.

The advantages in a nutshell:

  • the Clear Sky filter stops airglow and scattered light
  • suitable for small and medium-sized telescopes
  • a real interference filter - only the important wavelengths pass through the eyepiece
  • 1.25" thread - suitable for all 1.25" eyepieces

  • Shop: Omegon Filters 1.25'' Clear Sky filter (

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