The Astronomik CLS (City Light Suppression) CCD EOS Clip is a great filter against light pollution in a clip design for Canon EOS DSLRs. It blocks emissions of artificial light sources like streetlights and airglow.
It enhances the contrast between our “desired” objects and the background.
92% transmission at 486nm (H-beta),
92% transmission at 496nm (OIII),
92% transmission at 501nm (OIII),
97% transmission at 656nm (H alpha), pass from 450 to 540nm and from 640 to 690nm.
Unfortunately with unmodified DSLR cameras (like my 100D) the images have a strong cyan-blue tint. (check here how to remove it)
Depending on your processing software it is important to do a custom white balance at daylight (noon) with inserted filter and use this profile for astrophotography. For PixInsight it doesn’t matter what type of white balance is used, if DSLR_RAW is set to “Pure RAW”.
Anyway, the results with the filter are far better for heavy light polluted areas.
Location: My balcony in Derendingen (454m), Solothurn, Switzerland – see light pollution map below
Date/Time: 01/04/2016 19:24h CET (shot 1) – 19:27h CET (shot 2)
Camera: Canon EOS 100D
Lens: Canon EF 50mm f/1.4
Tracker: Sky Watcher Star Adventurer
Sorry for the fine clouds… the wheater this evening was not excellent.
Check here my recent DeepSkyStacker settings. It removes successfully the cyan-blue tint to a very acceptable level 😀