Baader DSLR ACF Filters are manufactured with strict blocked transmission in the blue and red part of the spectrum, so that the white balance of the camera for daylight shots is much more successful in spite of the H-alpha passage. In addition, this improved IR and UV-blocking enables a reduction of the halos around bright stars, which otherwise often occur when an inexpensive refractor telescope is used for astronomical photography.
The Baader ACF filter has to be installed in the camera body replacing the original one.