Astronomik 31mm CLS-CCD Filter

The CLS-CCD Filter enhances the contrast between astronomical objects and the background. Due to the wider transmission curve compared to UHC filters, a greater amount of light will pass through the filter. Stars will be less dimmed. This filter has been optimized to block as much spurious light as possible and simultaneously provide the best performance for 'useful' light. A good filter for CCD and film B&W Film photography as well as observation of deep sky objects with telescopes or photo lenses with apertures of f/3 and above.

The filter completely blocks emission lines of artificial light sources like streetlights (e.g. sodium and mercury vapor) as well as airglow. All 'important' emission lines as well as the spectral range of the night adapted eye are passed. The supplementary IR blocking layer allows use with cameras without an integrated IR block filter.

The CLS is recommended for use in light polluted areas with colour cameras but also for use as a replacement for a normal UV/IR cut in the luminance channel for mono imaging