The Baader 1.25" Ultra-Narrowband 4.5nm S-II CCD Filter offers high contrasted images to about 673 nm in red spectral range. The S-II CCD filter offers sharper details of nebulae and the star appearance are diminished even stronger.
This IR-blocked filter has an anti-reflective coating to avoid halos and ghosting of the images for clear and sharper images. It is designed for fast optical system ranging from F8 - F3. Along with its 2 mm of thickness, this filter is planeoptically polished and has non-ageing sealed coated edges.