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Astronomik CLS Light Pollution Filter - Canon EOS APS Clip

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Astronomik CLS Light Pollution Filter - Canon EOS APS Clip

A CLS Light Pollution Filter - Canon EOS APS Clip by Astronomik:

The Astronomik CLS is a budget filter for visual observation, black and white photography and CCD photographs of nebulae, galaxies, and star clusters with astronomical instruments of any size.

The Astronomik CLS blocks the light of the spectral lines of mercury and sodium-vapor lamps and lets the largest part of the visible light and H-alpha emissions pass. All the important emission lines, as well as the spectral region that the very well dark adapted eye can see, can pass through the filter.

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 and even works well with binoculars.

The Astronomik CLS Light Pollution Filter is good for use under both dark and urban skies for reducing light pollution made by mercury-vapor lamps. For film photography and modified DSLR use, the CLS filter gives good performance and near perfect color balance. While this filter does perform well with webcam and video equipment under light polluted skies, it is not suitable for planetary use.


  • 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, color balance is near perfect CCD photography: Good, when used with an additional IR-block-filter
  • DSLR photography (original): Good, colour balance shifted but contrast enhanced
  • DSLR photography (astro-modified): Very good, color balance is near perfect
  • DSLR photography (MC modified): Good, when used with an additional IR-block-filter
  • Webcam / Video (Planets): Unsuitable
  • Webcam / Video (Deep Sky): Very good, if light pollution is a big problem

About the Astronomik Clip-Filter System: The patented Astronomik Clip-Filter System is black anodized aluminum and laser-cut on state-of-the-art modern machines. It can be inserted within seconds directly into the EOS camera body. There are no changes necessary and all lens functions (focus, screen, image stabilization) remain functional! 

Almost all Canon system lenses (with the exception of the EF-S series) and all M42 and T2 lens adapters, can be used with the Astronomik Clip-Filter System. The Clip-Filter System also acts as an outstanding dust shield, which prevents the possibility of dust settling on the sensor during long time exposure (The MC-Clear filter does not have a filter effect and only acts as a dust shield.)

Note: For Photographers interested in daylight IR-Photography a "MC-modification" is possible for some cameras. If you are interested in this, please send us a short mail. We will give you more details. The "MC-modification" gives you no advantage for normal astrophotography! If you have a full-frame EOS camera, like the 5D or 6D, you should buy the Astronomik CLS XL EOS Clip Filter instead.


Astronomik Visual CLS Light Pollution Filter - Canon EOS Clip Features:

  • 92-percent transmission at 486 nm (H-beta)
  • 92-percent transmission at 496 nm (OIII)
  • 92-percent transmission at 501 nm (OIII)
  • 97-percent transmission at 656 nm (H-alpha)
  • Pass from 450 to 540 nm and beyond 650 nm
  • Parfocal with other Astronomik filters
  • Glass thickness: 1 mm
  • 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


OPT Product Number: AK-CLS-EOS



Filter TypeCLS
Free ShippingYes
ShapeCanon APS/ C
Warranty10 Year Warranty

Customer Reviews

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United States

First time using a clip in LPS filter.

The filter came well packaged, no surprises and was exactly what I expected. Seemed a little too easy to use so I watched a couple of YouTube videos to make sure I was installing it correctly. Sure enough just clip the filter in and your ready to go...just had to wait for a clear night to test it. I live in a little pocket of dark sky within a big city and I was totally amazed at how clear and crisp my images were once the night sky was clear. I used a Canon t7i with a full frame 50mm and large 400mm prime and was able to capture clear images of Pléiades from my backyard. My camera is unmodifided but once I do have the Astro-modification done I will update my filter to the CLS-CCD version for use with eather my lenses or telescope depending on how much time and clear sky’s I have for the night.

James H.
United States

great results and great fit

Title is completely accurate, huge improvement vs no filter, mechanically perfect mount, easy install and removal... but 4 stars not 5 because the resulting bluish tint will indeed require post-processing on any images you intend to really use and enjoy, share w/ others.

Floyd W.
United States

Light pollution filter

It’s the only LP that that I have tried that actually does improve images in a helpful way under heavy light pollution conditions

Jon G.
United States

Definitely improved astrophotography from my city dwelling.

I live in San Diego, just a quarter mile from the ocean, and my skies are heavily light polluted. Most nights I’m lucky to make out a dozen stars. My very first night with the Astronomik CLS filter in my Canon Eos T6i (unmodified) resulted in a beautiful image of the globular cluster M4, on a night when I could barely see the adjacent star Antares. I was blown away. I’ve used it several nights since with equally good results. Definitely recommend for light polluted skies. On the other hand, don’t forget to take it out when you’re in a nice dark sky setting.

Terry P.
United States

LP camera filter

The filter inserts easily into the Canon camera. I image from a very light polluted area in Florida, and it’s amazing the amount of light the filter blocks. I use a CMOS camera on my main scope with other astronomic filters, but I also like to capture constellations and large open star clusters with a camera and lens setup. Before I bought the filter I could not use the camera as a standalone imaging unit without traveling many miles to a dark site. Now using the filter I can set up at home and capture excellent images through the camera. These filters are not cheap but they are worth every penny if you want to block light pollution.

A OPT  Customer
Michael E.
United States

Great Filter for a camera with modification

Filter works great with my 700d modified. I have an internal mod by Hap Griffin. Astrodon uv/ir filter (Luminence). I tried 300 second / 5 minute subs last night with a 65 mm quad. Th data looks good thus far. I live in a light polluted are in Northeastern PA. Wilkes-Barre/Scranton area.