This 47.4mm round Baader 4nm f/2.0 Ultra-Highspeed CMOS Filter from Alpine Astronomical is recommended for extremely fast optical systems from f/3.4 to 1.8, and is designed for the special filter requirements of fast optics like Celestron RASA astrographs. This filter is unmounted for use in the Baader FCCT (Filter Changer Camera Tilter). The filter features a Reflex-Blocker hard coating, which has been planoptically polished, and has Life-Coat sealed edges. It is equally suitable for modern CMOS sensors as well as for older CCD camera technologies.
