CLS filters

The CLS filters are general purpose deepsky filters which blocks the light from Hg and Na lamps, but transmits all the other wavelengths.

There are wider and narrower filters. But what might be the difference between them in practice? It depends on heavily the selected targets.

They work as a contrast enhance filter for emission, planetary nebulae and supernova remnants. They're also work for all other objects with wider spectrum as well, like stellar clusters, galaxies, open- and globular clusters if our sky is light polluted.