Astronomik CLS Visual Deep Sky & Light Pollution Filter 1.25-in

Product code: 8h0053
£67.00
An excellent general purpose light pollution filter - perfect for astrophotography and visual use.
You will earn 67 points with this purchase
Astronomik CLS Visual Deep Sky & Light Pollution Filter 1.25-in
The Astronomik CLS  light pollution filter works on all objects for both visual use, and imaging with standard and Baader modded DSLR cameras. Blocks Sodium, Mercury and air-glow emission typically from street lighting. It is a great deep sky and general purpose filter. Not UV / IR blocked.

Main use

The filters are optimized for use with aperture ratios from 1:3 to 1:15. Transmission losses and chromatic distortions, which are problems with other filters, only appear with Astronomik filters when extremely bright aperture ratios of 1:2 and more are used. The CLS filter is suitable for use with telescopes of all aperture sizes.

Suitability

  • Visual observation (dark skies): Good, to reduce light pollution by mercury-vapour lamps (streetlight)
  • Visual observation (urban skies): Good, an UHC-E or UHC filter is more suitable
  • Film photography: Very good, colour balance is near perfect
  • CCD photography: Good, when used with an additional IR-block-filter (!)
  • DSLR photography (astro modified): Very good, colour balance is near perfect
  • DSLR photography (MC modified): Good, when used with an additional IR-block-filter
  • DSLR photography (original): Good, colour balance shifted but contrast enhanced
  • Webcam / Video (Planets): Unsuitable
  • Webcam / Video (Deep Sky): Very good, if light pollution is a big problem

Technical Data

  • 97% transmission at 656nm (H alpha)
  • 92% transmission at 486nm (H-beta)
  • 92% transmission at 496nm (OIII)
  • 92% transmission at 501nm (OIII)
  • pass from 450 to 540nm and beyond 650nm
  • 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
How to read the chart
  • The horizontal axis is the Wavelength in Nanometers (nm). 400nm is deep blue, at 520nm the human eye senses green and at 600nm red. At 656nm is the famous "H-Alpha" emission line of hydrogen.
  • The transmission in % is plotted on the vertical axis.
  • The red line shows the transmission of the filter.
  • Visual filters: The grey line in the background shows the relative sensitivity of the human eye at night. The maximum is at ~510nm and drops to longer and shorter wavelengths. You can easily see, that you can´t see anything of the H-alpha line at night (even if you can during daylight!) The sensitivity at 656nm is 0% at night!
  • Photographic filters: The grey line in the background shows the sensitivity of a typical CCD sensor.
  • The most important artifical emission lines are shown in orange. The artifical light pollution is dominated by see mercury (Hg) and sodium (Na), which are used in nearly all streetlights.
  • The most important emission lines from nebulas are shown in green. The most important lines are from ionized Hydrogen (H-alpha and H-beta) and double ionized oyxgen (OIII).Astronomik CLS Light Pollution Filter
Own this product? Let us know what you think.
Brand Astronomik
Condition New
Product Code 8h0053