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Radian Telescopes 2" Triad Ultra Quad-Band Narrowband Filter

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  • Regular price $1,075.00

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Accessories Added

  • 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


Radian Telescopes 2" Triad Ultra Quad-Band Narrowband Filter

The Radian Triad 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 3mm.

Since the filter has extremely narrow bandpasses, 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. Telescopes with focal ratios faster than f/2.8 having diminished throughputs at the nominal wavelengths. Between f/2.2 and f/2.8 will have about 0.8nm band-shift.



Filter ShapeRound
Filter Size2"
Filter Thickness3mm
Filter TypeQuadband


  • 2" Triad Ultra Filter
  • Filter case

Customer Reviews

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Eddie Hunnell

Triad Ultra 2" first image

A friend bought this filter and loaned it to me two weeks ago. I have a C11 Edge with a focal reducer and a ZWO ASI128MC Pro camera. I took a shot at the horsehead nebula with it from a light polluted (Bortle 7-8, closer to 8) sky and 2 street lights out my back yard. I have to say it did a great job. You can see the image here: . I used subs from 2 different nights. I got reflections around Alnitak. And I got reflections from Alnitak in the bottom right (2 different ones due to the 2 different nights of subs). I did my best to remove them in Pixinsight. It really removed a lot of the light pollution. I think there is a little color distortion (I think the Flame Nebula and Horsehead Nebula should not be as similar in color). Overall I have to say I love the filter. But I do think it is priced too high. I gave it 4 stars. It would be 5 if it was priced better. That is what is holding me back from buying it (and I do have $10k in my setup so it is not like I am only buying $100 filters - getting a RASA 11" this weekend and will buy the $500 LPS for it). Over $1000 just seems too high. Please reduce the price a little. Eddie Hunnell Longmont, CO, USA