400D BCF korrigeringsfilter

- 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!