Product series:
The photography of galactic nebulae with extremely fast optics can only really be effective with the f/2 Highspeed filter.
The full width at half maximum of this filter is optimised for fast apertures of f/1.8 to f/3.5, where despite the high line broadening at this aperture ratio, a high contrast is still possible.
The filters are also ideal for Celestron RASA Astrographs.
