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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 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. Telescopes with focal ratios faster than f/2.8 are incompatible with the Triad Ultra filter.



Filter ShapeRound
Filter Size2"
Filter Thickness3mm
Filter TypeQuadband


  • 2" Triad Ultra Filter
  • Radian microfiber cloth
  • Filter case

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Eddie Hunnell Verified Buyer

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