The H-alpha 7nm CCD Narrowband-Filter Dia 31mm are very often used for astrophotography. They provide very good contrast when photographing diffuse nebulae which emit H-alpha light, like the North America Nebula. The Baader H-alpha filter blocks the entire visible light, except a small passage in the red H-alpha light. This offers some advantages. The entire stray light of cities is hidden, so beautiful photographs are possible even close to a city. Star images from refractor telescopes are significantly improved, the stars become sharper. Combined with Baader O-III and S-II CCD narrowband filters, exciting false color images are possible.
Features
Maximal contrast through steep edges.
Dual cavity design for focal ratio f/3 to f/10
Best sharpness through plane-parallel surfaces.
Resistant to aging through optimal sealing also at the edge.
The Baader H-alpha filter blocks the entire visible light