Skip to content
Stargazing May 4th ✦ 6pm-10pm
Stargazing May 4th ✦ 6pm-10pm

Baader 3.5 / 4nm f/2 Ultra-Highspeed Filter Set – CMOS-optimized (H-alpha, O-III, S-II)


Delayed Shipping More on the way:
This product will not ship immediately. Contact us for estimated delivery.

      • Baader H-alpha / O-III / S-II f / 2 Ultra-Highspeed 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 extremely fast optical systems from f / 3.4 to f / 1.8
      • Specially designed for the special filter requirements when used with highly opened optics such as the Starizona HyperStar and Celestron RASA astrograph
      • 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