Astronomik CLS
The relentless spread of urbanization and its associated light pollution have become a growing problem for all amateurs and astrophotographers. The current fixes to the problem can be expensive and might include the purchase of a monochrome camera, several types of narrowband filters and a filter wheel.
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.
Bandpass
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, colour 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, colour balance is near perfect
DSLR photography (MC modified): Good, when used with an additional IR-block-filter