Baader

Increased contrast
Ever more narrow passbands
Reflex-Blocker™ coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics

Baader H-alpha/O-III/S-II f/2 Ultra-Highspeed Filtersets – Premium Grade. 3.5nm/4nm FWHM (to harmonize the exposure time from H-alpha with O-III / S-II), recommended for extremely fast optical systems from f/3.4 to f/1.8

The Baader SunDancer II (with heated H-alpha Etalon from SolarSpectrum) transforms an existing telescope quickly and easily into a professional H-alpha telescope!