Alpine Astronomical Baader 3.5/4nm f/3 Ultra-Highspeed H-Alpha CMOS Filter (31mm, Unmounted)

This 31mm, unmounted Baader 3.5/4nm f/3 Ultra-Highspeed H-Alpha CMOS Filter from Alpine Astronomical is recommended for extremely fast optical systems from f/3.4 to 2.3 and is particularly designed for the special filter requirements of f/3 optics. The filter features a Reflex-Blocker hard coating, which has been optically polished, and has Life-Coat sealed edges. It is equally suitable for modern CMOS sensors as well as for older CCD camera technologies.