The CLS Clip-Filter (for The Canon EOS APS-C)
The CLS (City Light Pollution) Filter, from Astronomik, is designed to clip-in to (many models of) Canon EOS DSLR cameras. The specific filter which I was loaned for this review, is The CLS CCD Clip-Filter EOS APS-C.The CCD designation indicates that the filter is designed for use with CCD cameras (obviously!), but also IR-Modified DSLR cameras as well as Black & White film astrophotography.
Recommended for use with optical instruments/lenses of all apertures, with a focal ratio of f/3 or higher.
This particular offering from Astronomik would be of great interest to the increasing number of astrophotographers using infrared modified DSLR cameras.
The filter fits in front of the sensor/shutter area of the camera (the area exposed whenever a lens is removed). Be advised: These types of filters don't always produce an audible "click" when inserted. It's important to take your time and use care whenever installing or removing these filters. Ensure the filter is properly seated; I sometimes test to see if it's snugly in place, by slowly tilting the camera. It's a good idea to have a clean microfiber cloth (or other suitable clean material) held directly underneath, in case the filter does in fact slip out.
The Clip-In Filter arrives very well packaged; in a foam-lined plastic case. It looks like it would be right at home even in a Professional observatory.
The Astronomik CLS CCD filter features an integrated IR blocking layer, which is very useful (and convenient) for use in Astro-modified DSLRs.
The filter is available in many different configurations and sizes. As you can see on the links below, you should have no trouble finding the filter housing you need for your specific purpose.
I found the Clip-In Filter very easy to use. However, I would have preferred to have it actually snap into place - with an audible "click". So that I could have an additional indicator, as to whether it is completely seated or not.
On a related note: I've learned of some hobbyists, using a very small (Jeweler's size) flat-head screwdriver, to carefully expand the two small tension "fingers" on the black filter housing - To ensure a snug fit when inserting in camera. I have not had the need to try this "work around" on my filter. Nor would I in any case, as this filter was (graciously) loaned to me for review, by the kind folks at Astro-Shop in Germany.
Here's the Link to the (Google-translated) English version of this Site.
Again, the detailed specifications of The CLS series of filters, may be seen on this page of the Astronomik site.
These are basically high-quality light pollution filters, which are available for a reasonable price. They are simply ideal for anyone imaging from an area with light pollution.
My former residence, where I made my astrophotgraphy attempts, was under Bortle 8/9 skies. Very close to the worst possible level of light pollution. Under skies like that, The CLS CCD Clip Filter is a necessity!
It would be very difficult to get any good sub-exposures, without a good light pollution filter in place. In use, I've found the filter to do an excellent job of eliminating light pollution. And more importantly, without any multi-color gradients in the resulting images; as I've experienced with both the IDAS Light Pollution Filter from Hutech and The "CLS" CCD Clip-In Filter from Optolong.
I plan to add a few more examples of astrophotos, taken with The Astronomik CLS CCD Filter, The Optolong "CLS CCD" Filter, and possibly even The Hutech IDAS Filter; so that you'll be able to better form your own conclusions, etc.
As for my recommendation, when it comes to light pollution filters for photographic use, I'd simply stick with the products made by Astronomik - And avoid the others.
But, for now, I'd like to share a couple of the images (from 2 different filters) for comparison:
A section of Cassiopeia, featuring NGC 281 (The Pacman Nebula) in the center of the FOV.
Bear in mind, that these are single frame / sub-exposures of 30 seconds each, using an 85mm lens, with ISO 1600. Everything was the same, except for the clip-in filters.
Camera used, was my IR-Modified Canon T5i. A simple, homemade motorized barn door tracker was used as the mount. No additional filters were used, these are as shot, directly from the SD card:
Wide Field NGC 281
Optolong CLS-CCD Filter 30" NGC 281
Wide Field NGC 281
Astronomik CLS-CCD Filter 30" NGC 281
The first difference you've probably noticed between these results, is the strong red/magenta hued gradient throughout the exposure taken with The Optolong CLS-CCD Filter in place.
I always do my best to avoid light pollution filters which produce these unnatural color gradients, etc.
As you can see, The Astronomik CLS-CCD Clip-In Filter does not produce any of these unnatural colors. Which translates into having more accurate sub-exposures for stacking, from the start.
I have a couple of more examples, which illustrate the same differences as those above. Including images processed (identically) in Adobe PhotoShop and other photo editing software applications. As well as stacked & processed images (I look forward to adding them here soon).
As for The Astronomik CLS-CCD Clip-Filter, it was originally designed, produced, and named (CLS-CCD) by Astronomik in Germany. It is manufactured using very high-quality materials and processes. And the effort put forth by Astronomik is obvious when one looks at the results.
The Astronomik CLS Clip-Filter may be purchased from:
This particular review was not as lengthy as I originally envisioned it. However, I have acquired some additional images, as well as data in the form of notes, etc. So, I do hope to add some additional technical details here in the near future.
Clear skies!
