Lunático Astronomía

Astronomik CLS-CCD Filter


CCD filter to reduce light pollution. Enhance the contrast between deep-sky objects and the sky background.


The Astronomik CLS CCD is suitable under light-polluted skies for DSLR Cameras, which have been remodeled for astronomical use. The filter enhances the contrast between all deep-sky objects and the background.

The CLS-CCD Filter enhances the contrast between astronomical objects and the background. Due to the wider transmission curve compared to UHC filters, a greater amount of light will pass the filter. Stars will be less dimmed. This filter has been optimized to block as much spurious light as possible and simultaneously provide the best performance for ‘useful’ light. A good filter for DSLR-, CCD- and film b/w-photography as well as observation of deep-sky-objects with telescopes or photo lenses of all aperture f/2 and above.

Main use

The filter blocks completely emission lines of artificial light sources like streetlights (e.g. sodium- and mercury-vapor) as well as the airglow. All ‘important’ emission lines as well as the spectral range of the night-adapted eye are beeing passed. The supplementary IR-blocking layer allows the use for DSLR- and Webcams without an integrated IR-block filter.

Other uses

      • Easier resolution of Double Stars.
      • With the EOS-Clip model, photography with DSLR cameras is feasible even unter extreme light-polluting conditions without shifting the white balance.
      • The 1,25″ and 2″ socket models can be used for observations from light-polluted areas.
      • If you plan to create color images from emission line data, Astronomik CLS-CCD filter is a great choice for the Luminance channel


CLS: For cameras with an integrated IR-filter or for visual observation.

30 sec. exposures with JPEG data directly out of the camera without any further processing  (Canon EOS M3 MC-modified, ISO 1600, Walimex 12/2.0).

The first image without filter, the second with CLS-CCD filter.

Transmission curve:

Technical Data

  • 95% transmission at 486nm (H-beta)
  • 95% transmission at 496nm (OIII)
  • 95% transmission at 501nm (OIII)
  • 97% transmission at 656nm (H-alpha)
  • pass from 450 to 520nm and from 640 to 690nm
  • Parfocal with other Astronomik filters
  • Glass thickness: 1mm
  • Completely resistant against high humidity, scratches, and aging effects
  • Diffraction limited, the filter will not reduce the optical performance of your telescope!
  • Astronomik filters are delivered in a high-quality, long-lasting, filter box
  • Since 2008 we do ship filters with a completely new design. Any kind of halo or strange reflection is a matter of past

Available in other sizes and formats. If you do not find the size you want, contact us at




Filter thread

Clip-Filter EOS APS-C, Clip-Filter EOS XL, 1,25", 2", Ø 31, Ø 36, Ø 50, 50x50mm.