Baader Narrowband 3.5nm H-alpha Filter Square
50x50mm square unmounted
These 3.5 nm H-alpha Enforced-Narrowband Filters open up the extremely narrow 3.5nm H-alpha world.
This enforced contrast results in even fainter stars, providing more signal of faintest nebulae detail. Manufacturing such ultra-narrow filter does require extreme coating homogeneity and very high CWL precision, which these filters are designed for (CWL= Center-wavelength)