CLS filters are broadband filters, which means they allow wide incident light wavelength ranges to pass through. They block light only in selected sections of the spectrum. These blocked sections are chosen in such a way that they coincide with the emissions from artificial light sources. In addition to artificial sources, there are also natural sky brightness phenomena, which are also blocked by CLS filters. Ultimately, the sky background appears darker with a CLS filter. The object being observed stands out more clearly against the background.
![Omegon Filters Pro 2'' CLS filter](/Produktbilder/normal/47291_1/Omegon-Filters-Pro-2-CLS-filter.jpg)
Omegon
Filters Pro 2'' CLS filter
$ 99.00
![Omegon Filters Light Pollution Filter, 2”](/Produktbilder/normal/15630_1/Omegon-Filters-Light-Pollution-Filter-2r.jpg)
Omegon
Filters Light Pollution Filter, 2”
$ 59.00
![Omegon Filters 1.25'' deep sky filter](/Produktbilder/normal/33217_1/Omegon-Filters-1-25-deep-sky-filter.jpg)
Omegon
Filters 1.25'' deep sky filter
$ 89.00
![Omegon Filters 1.25'' Clear Sky filter](/Produktbilder/normal/33216_1/Omegon-Filters-1-25-Clear-Sky-filter.jpg)
Omegon
Filters 1.25'' Clear Sky filter
$ 129.00
![Omegon Filters Pro Nebula CLS Deep Sky Filter 1,25''](/Produktbilder/normal/47290_1/Omegon-Filters-Pro-Nebula-CLS-Deep-Sky-Filter-1-25-.jpg)
Omegon
Filters Pro Nebula CLS Deep Sky Filter 1,25''
$ 69.00
![Optolong Filters Clear Sky Filter 82mm](/Produktbilder/normal/69501_3/Optolong-Filters-Clear-Sky-Filter-82mm.jpg)
Optolong
Filters Clear Sky Filter 82mm
$ 244.00
![Optolong Filters Filter L-eNhance 1.25](/Produktbilder/normal/65041_1/Optolong-Filters-Filter-L-eNhance-1-25.jpg)
Optolong
Filters Filter L-eNhance 1.25
RRP:
$ 211.00
Our price:
$ 200.00
![Optolong Filters Clear Sky Filter 77mm](/Produktbilder/normal/67558_2/Optolong-Filters-Clear-Sky-Filter-77mm.jpg)
Optolong
Filters Clear Sky Filter 77mm
$ 188.00
![STC Filters Astro Multispectra Filter 2"](/Produktbilder/normal/60918_1/STC-Filters-Astro-Multispectra-Filter-2-.jpg)
STC
Filters Astro Multispectra Filter 2"
$ 389.00
![Chroma Filters LoGlow Light Pollution 1.25"](/Produktbilder/normal/66049_1/Chroma-Filters-LoGlow-Light-Pollution-1-25-.jpg)
Chroma
Filters LoGlow Light Pollution 1.25"
$ 560.00
![Chroma Filters LoGlow Light Pollution 2"](/Produktbilder/normal/66049_1/Chroma-Filters-LoGlow-Light-Pollution-2-.jpg)
Chroma
Filters LoGlow Light Pollution 2"
RRP:
$ 980.00
Our price:
$ 630.00
![Astronomik Filters CLS Clip Nikon Z XL](/Produktbilder/normal/71078_1/Astronomik-Filters-CLS-Clip-Nikon-Z-XL.jpg)
Astronomik
Filters CLS Clip Nikon Z XL
$ 222.00
![IDAS Filters Night Glow Suppression Canon EOS APS-C](/Produktbilder/normal/57332_1/IDAS-Filters-Night-Glow-Suppression-Canon-EOS-APS-C.jpg)
IDAS
Filters Night Glow Suppression Canon EOS APS-C
RRP:
$ 400.00
Our price:
$ 366.00
![Omegon Filters Nebula/ city light filter 1.25 ''](/Produktbilder/normal/15629_1/Omegon-Filters-Nebula-city-light-filter-1-25-.jpg)
Omegon
Filters Nebula/ city light filter 1.25 ''
$ 39.90
![Astronomik Filters CLS CCD 50mm](/Produktbilder/normal/52920_1/Astronomik-Filters-CLS-CCD-50mm.jpg)
Astronomik
Filters CLS CCD 50mm
$ 255.00
![Astronomik Filters CLC Canon EOS clip filter APS-C](/Produktbilder/normal/16744_1/Astronomik-Filters-CLC-Canon-EOS-clip-filter-APS-C.jpg)
Astronomik
Filters CLC Canon EOS clip filter APS-C
$ 144.00
![Vaonis Filters CLS Filter for VESPERA](/Produktbilder/normal/78231_1/Vaonis-Filters-CLS-Filter-for-VESPERA.jpg)
Vaonis
Filters CLS Filter for VESPERA
$ 255.00
![Astronomik Filters CLS XT Clip Canon EOS APS-C](/Produktbilder/normal/16744_1/Astronomik-Filters-CLS-XT-Clip-Canon-EOS-APS-C.jpg)
Astronomik
Filters CLS XT Clip Canon EOS APS-C
$ 166.00
![Astronomik Filters CLS Sony Alpha Clip filter](/Produktbilder/normal/53729_1/Astronomik-Filters-CLS-Sony-Alpha-Clip-filter.jpg)
Astronomik
Filters CLS Sony Alpha Clip filter
$ 222.00
![Astronomik Filters CLS XL Clip Canon EOS R](/Produktbilder/normal/64938_2/Astronomik-Filters-CLS-XL-Clip-Canon-EOS-R.jpg)
Astronomik
Filters CLS XL Clip Canon EOS R
$ 222.00
![Explore Scientific Filters 1.25" CLS filter](/Produktbilder/normal/54536_1/Explore-Scientific-Filters-1-25-CLS-filter.jpg)
Explore Scientific
Filters 1.25" CLS filter
$ 88.00
![Explore Scientific Filters 2" CLS filter](/Produktbilder/normal/54535_1/Explore-Scientific-Filters-2-CLS-filter.jpg)
Explore Scientific
Filters 2" CLS filter
$ 122.00
![Astronomik Filters CLS CCD XL Clip Canon EOS R](/Produktbilder/normal/64980_1/Astronomik-Filters-CLS-CCD-XL-Clip-Canon-EOS-R.jpg)
Astronomik
Filters CLS CCD XL Clip Canon EOS R
$ 277.00
![Astronomik Filters CLS CCD EOS M Clip filter](/Produktbilder/normal/52919_1/Astronomik-Filters-CLS-CCD-EOS-M-Clip-filter.jpg)
Astronomik
Filters CLS CCD EOS M Clip filter
$ 177.00
![Astronomik Filters 2" CLS CCD filter](/Produktbilder/normal/16748_1/Astronomik-Filters-2-CLS-CCD-filter.jpg)
Astronomik
Filters 2" CLS CCD filter
$ 255.00
![Astronomik Filters CLS Canon EOS XL Clip](/Produktbilder/normal/43700_1/Astronomik-Filters-CLS-Canon-EOS-XL-Clip.jpg)
Astronomik
Filters CLS Canon EOS XL Clip
$ 200.00
![Optolong Filters L-Quad Enhance 2"](/Produktbilder/normal/80320_1/Optolong-Filters-L-Quad-Enhance-2-.jpg)
Optolong
Filters L-Quad Enhance 2"
RRP:
$ 266.00
Our price:
$ 255.00
![Astronomik Filters CLS CCD EOS clip filter](/Produktbilder/normal/16749_1/Astronomik-Filters-CLS-CCD-EOS-clip-filter.jpg)
Astronomik
Filters CLS CCD EOS clip filter
$ 177.00
![Optolong Filters L-Ultimate 1,25"](/Produktbilder/normal/79624_1/Optolong-Filters-L-Ultimate-1-25-.jpg)
Optolong
Filters L-Ultimate 1,25"
$ 289.00
![Astronomik Filters CLS CCD Clip Nikon XL](/Produktbilder/normal/66927_1/Astronomik-Filters-CLS-CCD-Clip-Nikon-XL.jpg)
Astronomik
Filters CLS CCD Clip Nikon XL
$ 266.00
![Astronomik Filters CLS M77](/Produktbilder/normal/66932_1/Astronomik-Filters-CLS-M77.jpg)
Astronomik
Filters CLS M77
$ 433.00
![Astronomik Filters 1.25" CLS CCD filter](/Produktbilder/normal/16747_1/Astronomik-Filters-1-25-CLS-CCD-filter.jpg)
Astronomik
Filters 1.25" CLS CCD filter
$ 111.00
![Optolong Filters L-Pro Filter 77mm](/Produktbilder/normal/73946_5/Optolong-Filters-L-Pro-Filter-77mm.jpg)
Optolong
Filters L-Pro Filter 77mm
RRP:
$ 400.00
Our price:
$ 320.00
![Astronomik Filters CLS Nikon XL Clip](/Produktbilder/normal/66927_1/Astronomik-Filters-CLS-Nikon-XL-Clip.jpg)
Astronomik
Filters CLS Nikon XL Clip
$ 222.00
![Astronomik Filters CLS Canon EOS M Clip filter](/Produktbilder/normal/52887_1/Astronomik-Filters-CLS-Canon-EOS-M-Clip-filter.jpg)
Astronomik
Filters CLS Canon EOS M Clip filter
$ 155.00
![Optolong Filters L-Pro Clip Sony Full Frame V2](/Produktbilder/normal/79800_1/Optolong-Filters-L-Pro-Clip-Sony-Full-Frame-V2.jpg)
Optolong
Filters L-Pro Clip Sony Full Frame V2
$ 266.00
The figure below illustrates the principle using the example of the NGS1 filter from IDAS. The black transmission curve shows which wavelength ranges the filter allows to pass through. 100% would mean no filter effect at all. The transmission curve also shows which light wavelength ranges are blocked by the filter. These ranges are associated with the emissions from sodium-vapour lamps and other disruptive light sources. The CLS filter filters out this unwanted light.
The CLS filter allows broad ranges to pass through and is therefore also suitable for small optics.