S-II 50.4mm f/2 Ultra High Speed Filter (4nm) - Optimized CMOS
Baader CMOS S-II f/2 50.4mm x 3mm Ultra High Speed Filter - Premium Grade
4nm FWHM, recommended for extremely fast optical systems faster than f/2.3
Specially designed for special filter requirements when used with extremely high aperture f/2 optics such as Celestron's RASA astrographs.
Enables the highest contrast even in the strongest light pollution, minimizes star size, makes the finest detail of the nebula accessible - indispensable under Bortle skies 9/8/7/(6)
Plano-optically polished, hard-coated Reflex-Blocker™ with sealed coating edges (Life-Coat™)
Blackened edges all around, with front filter indicator in the form of a black outer rim on the side of the telescope
Optimized for modern CMOS cameras, equally suitable for CCD camera technologies