Lumicon Hydrogen-Beta Filter
The Lumicon H-Beta Filter isolates only the Hydrogen-beta line of the spectrum (486.5nm) while completely blocking the rest of the overall spectrum of light. The result is extreme contrast between the black background of space 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.
With this filter, all nebulae may be checked for H-beta emissions, with reference to views given by your other Lumicon filters.
Not intended for photography.