Baader Narrowband enforced 3.5nm H-alpha Filters are precision grade for f/10 to f/3.5 optical systems.
Designed for imaging the extremely narrow 3.5nm H-alpha band. The enforced contrast results in much fainter stars providing more signal in the fainter nebula details.
The manufacture of such ultra-narrow filters requires extreme coating homogeneity and very high center-wavelength (CWL) precision. Each filter is planeoptically polished and hard coated.
These are available in sizes: 2" Mounted (#2459454), 50.4mm round unmounted (#2459455) and 50x50mm square unmounted (#2459456).
Important: These filters are intended only for imaging use. They are not suitable for any form of solar filtration. Please see our solar filter section for filters designed specifically for safe solar use.
Below is the real filter-spectrum, taken with an MPI-DADOS-Spectrograph. Comparision with the solar-spectrum (including solar absoprtion lines).