Baader 4nm Ultra-Narrowband OIII Filter - CMOS-Optimized

• Baader H-alpha / O-III / S-II Ultra-Narrowband (Narrowband) filter set - Premium Grade
• 3.5 / 4 nm half width (to harmonize the exposure time of H-alpha with O-III / S-II), recommended for optical systems from f / 10 to f / 3.5
• Enables the highest contrast even with the strongest light pollution, minimizes the size of the stars, makes the finest nebula details accessible - indispensable under Bortle 9/8/7 / (6) sky
• Reflex-Blocker ™ hard-coated and optically polished - with sealed coating edges ( Life-Coat ™ )
• Blackened edges all around, with a filter front indicator in the form of a black outer edge on the front
• Optimized for modern CMOS cameras, but ideally suited for CCD camera technologies

The new generation of Baader CMOS-optimized filters features:

• CMOS-Optimized Baader Filter
• Increased contrast
• Ever more narrow passbands
• Reflex-Blocker™ coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
• FWHM on each filter category carefully designed to allow for 1:1:1 exposures, matched for typical CMOS quantum efficiency and s/n ratio
• Identical filter thickness to existing standards, with utmost care for parfocality
• Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
• Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed read more)
• Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment