The Lumicon H-Beta Filter isolates only the Hydrogen-beta line of the spectrum (486.5nm) while blocking, completely, the rest of the overall spectrum of light. The result is extreme contrast between the black background and the delicately attenuated H-beta light needed to view a few select, extremely faint objects such as the Horsehead, Cocoon and California Nebulae. In may cases the Lumicon H-beta Filter is the ONLY way to view those objects.
A steady, transparent sky, 8" or larger aperture (in most cases) and a maximum-efficiency exit pupil (7mm), combined with the Lumicon H-beta Filter, all make an unbeatable combination for viewing those "notch in the belt" objects. Lumicon measures every filter individually on a Perkin-Elmer Double-Beam spectrophotometer, inscribing on the filter its % transmission for the primary H-beta Line.
Not intended for photographic use.