Delivering the absolute highest contrast deep sky images in H-Alpha, H-Beta, Oxygen III and Sulfur-II, Baader Planetarium"s Premium Narrowband CCD passfilters are a must have when it comes time to excellent photography and observation. With the shortest exposures possible, the ultra-narrow bandwidths have extremely high transmission while completely rejecting light pollution and blocking longer wavelengths. Baader"s high optical quality narrowband filters guarantee no loss in sharpness or contrast making it a superb filter that is a must have for enthusiasts" collections.Delivering a smooth and accurate 1/4 wavefront over the entire surface, each substrate is fine-optically polished delivering exceptional performance. The special custom polishing operation Baader executes on all Narrowband passfilters is the difference when comparing standard commercially precision polished filter substrates most all other filter manufacturers use.