search-iconSearch
Call for Advice: 01442 822997 
Astronomik CLS Filter 2-in

Astronomik CLS Visual Deep Sky & Light Pollution Filter 2 in

product code: 8H0054
£143.00
out of stock
An excellent general purpose light pollution filter - perfect for astrophotography and visual use.
Out of stock. Please use our stock alert to be notified when ready.
you will earn 143 points with this purchase
Astronomik CLS Visual Deep Sky & Light Pollution Filter 2 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.
write a review
Brand Astronomik
Condition New
Product Code 8H0054