Features: Baader 3.5 / 4nm Ultra-Narrowband-Filterset 2 Inch
2" x 2 mm Baader CMOS H-alpha / O-III / S-II Ultra-Narrowband Filter Set – Premium Grade – with 2" (M48) filter thread
3.5 / 4 nm FWHM (to harmonize the exposure time from H-alpha with O-III / S-II), recommended for optical systems from > f/3.4
For highest contrast even at strongest light pollution, minimizes star size, emphasizes finest nebula detail – indispensable under Bortle 9/8/7/(6) skies
Reflex-Blocker™ hard coated and planeoptically polished – with sealed coating edges (Life-Coat™)
Blackened edges all around, with filter-lead-side-indicator in the form of a telescope-sided black outer rim
Optimized for modern CMOS cameras, but likewise excellent for CCD camera technologies
Mounted in Baader Low Profile Filter Cell (LPFC) – 6 mm height
Specification: Baader 3.5 / 4nm Ultra-Narrowband-Filterset 2 Inch