Baader's new Narrowband CCD Emission Line & H-Alpha 50.4mm (2") unmounted Filters with 3mm glass deliver the absolute highest contrast deep sky images in H-Alpha, Oxygen III, and Sulfur-II, with the shortest exposures possible. Their ultra-narrow bandwidths have extremely high transmissions, while completely rejecting light pollution as well as the important blocking of longer wavelengths.
The high optical quality of Baader narrowband filters guarantees no loss in sharpness or contrast. Each substrate is fine-optically polished plane parallel to deliver a smooth and accurate 1/4 wavefront over the entire surface. This special custom polishing operation sets Baader filters apart from the standard commercially precision polished filter substrates used by most other filter manufacturers.
In addition to their special transmission properties, the Baader coatings were developed with another key goal in mind - to reduce the annoying reflections present in other astro-filters. To achieve this, along with excellent out of band blocking, required careful design and testing of the coating stacks.
Coatings are professionally applied in Germany by the most sophisticated equipment available today, ensuring high consistency for bandpass centering, transmission, and out of band blocking. The anti-reflection coatings are designed to prevent halos and balanced to prevent deformation of the substrates. The ultra-hard ionbeam deposition ensures the coatings will never degrade from use or normal cleaning.