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Astronomik CLS Light Pollution Filter - 50 mm Round - CLS-50R

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SKU: ASF-CLS-50R

Astronomik 50 mm CLS Light Pollution Filter


  • Eliminates orange glow produced by heavily light polluted metropolitan areas
  • Displays more stars and detail in nebulae
  • Best suited for telescopes with a filter to telescope aperture ratio of 1:3 to 1:15
  • 50 mm round format
  • The Astronomik CLS Filter provides nearly 100% transmission between 450 nm and 530 nm which includes the visual and h-alpha portion of the spectrum
  • All Astronomik filters feature multi-layer coatings for superior protection against scratching, aging and humidity
  • German-made for supreme optical quality!


More About the Astronomik 50 mm CLS Filter:


For imaging deep sky objects like star clusters, nebulae and galaxies in black & white as well as color with astronomical equipment of any size, the Astronomik CLS Filter is an excellent choice. By blocking the spectral lines of mercury and sodium-vapor lamps, and letting the largest part of the visible light and H-alpha emissions to pass, the CLS filter cuts off most surrounding light pollution, eliminating that annoying orange glare. Developed for use with filter to aperture ratios of 1:3 to 1:15. By staying within these parameters, aberrations and coma are eliminated.

All Astronomik filters are parfocal with all other Astronomik filters. The Astronomik 1.25" CLS Light Pollution Filter has a thickness of a mere 1 mm. It has a high resistance to scratches as well as the effects of aging and high humidity. This filter is diffraction limited and will not lower your telescope's optical performance. Astronomik filters arrive in a superior quality, durable plastic storage container.

Transmission Specifications:


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