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• The 31mm CLS Light Pollution Filter - Mounted in Low Profile Non-Threaded Cell by Astronomik:

  The Astronomik CLS is an excellent filter for black & white and color imaging of nebulae, galaxies and star clusters with astronomical instruments of any size. By blocking the spectral lines of mercury and sodium-vapor lamps, and letting the largest part of the visible light and H-alpha emissions pass, the CLS filter will effectively block out most surrounding light pollution, eliminating that annoying orange glare. 

  
  The filters are optimized for use with filter to aperture ratios of 1:3 to 1:15. By remaining within these aperture ratios, aberration and comma are eliminated.
  
  

  Now Mounted in Low Profile Non-Threaded Cell: Sometimes unmounted CCD filters can be hard to handle. The smaller diameters, such as this 31mm CLS filter, can be especially difficult to pick up and insert or remove from the filter wheel, and that can lead to possible damage as well as unwanted reflections from incorrectly installed filters. Astronomik has solved this problem by mounting their 31mm and 36mm filters in a low profile (3mm) non-threaded cell. O-rings, washers, or spacers are no longer required to hold the filter in place, and because the cell is only 3mm thick, it works well in all appropriately sized filter wheels. Mounted 31mm and 36mm Astronomik filters will also play nice with unmounted versions in the same carousel.

   

  Astronomik CLS Light Pollution Filter - Transmission Information:

  • 92-percent transmission at 486nm (H-beta)
  • 92-percent transmission at 496nm (OIII)
  • 92-percent transmission at 501nm (OIII)
  • 97-percent transmission at 656nm (H-alpha)
  • Pass from 450 to 540nm and beyond 650nm

   

  Features:

  • Parfocal with other Astronomik filters
  • Glass thickness: 1mm
  • Cell thickness: 3mm
  • Highly 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

   

  OPT Product Number: AK-CLS-31

   

• specifications

  Filter Type	Light Pollution/City Light Suppression
  Free Shipping	Yes
  Peak Transmission	97% at H alpha
  Shape	Round
  Size	31mm
  Warranty	10 Year Warranty