Radian Telescopes 65mm Triad Ultra Quad-Band Narrowband Filter

  • Shoot in any light polluted area
  • H-beta, OIII, H-alpha, and SII Band Passes
  • Works with any color camera including DSLRs
  • Exceptional narrow-band-luminance filter
  • Triad Ultra Filter: 65 mm square unmounted
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  • Regular price $1,995.00

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Radian Telescopes 65mm Triad Ultra Quad-Band Narrowband Filter

The Radian Triad Square filter has now been improved upon! With the Triad Ultra, you now have narrower band-passes, more light pollution reduction, higher contrast, better separation between H-beta and OIII channels, and sensitivity in the Sulfur II emission lines. Like the original Triad filter, the Triad Ultra is designed to work with color cameras but also as a narrow-band-luminance filter for monochrome cameras.

Hydrogen-beta Oxygen III Hydrogen-alpha Sulfur II
FWHM 5nm 4nm 4nm 4nm
Peak Transmission 79% 97% 87% 90%


The Triad Ultra is 100% American made and uses advanced multi-coatings and extreme tolerance glass, to ensure it is always consistent and accurate. Filter thickness is 3 mm.

Since the filter has extremely narrow band passes, telescopes with focal ratios faster than f/4 will move transmission off band. Telescopes with focal ratios between f/2.9 and f/3.9 are compatible with Triad Ultra, with lower transmissions. Between f/2.2 and f/2.8 will have about 0.8 nm band-shift.

Choose between the 2-inch threaded, 50 mm unmounted, 65 mm square unmounted, or 52 mm photographic thread filter sizes.

This filter is the 65 mm square unmounted selection.



Filter ShapeSquare
Filter Size65mm
Filter Thickness3mm
Filter TypeQuadband
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  • Triad Ultra Filter: 65 mm square unmounted
  • Filter case