Baader Filters 400D BCF Corrector Filter

– dramatically improves Halpha sensitivity

– significantly better sharpness is achieved by omitting the anti-aliasing AA filtering, which is completely unnecessary in astrophotography

– higher overall sensitivity due to better total transmission both in amplitude and spectral width

– reduced noise due to shorter exposure time at the same S/N ratio

– reduced colour aberrations when using normal 35mm lenses by increasing UV and IR blocking

Similar to illustration!