Radian Telescopes 2" 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
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  • Regular price $1,075.00

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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 5 nm 4 nm 4 nm 4 nm
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 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 0.8 nm band-shift.

The Triad 2-inch filter is housed in a 7 mm tall ring, with 5 mm height above the threads. The ring wall thickness is between 1.3 and 2.58 mm - depending on production batch. Please double check to make sure this will fit your filter wheel or accessories.


Filter ShapeRound
Filter Size2"
Filter Thickness3mm
Filter TypeQuadband
Free ShippingYes


  • 2-Inch Triad Ultra Quad-Band Filter
  • Filter case

Customer Reviews

4.8 Based on 4 Reviews
5 ★
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United States United States

Perfect solution for my shooting situation

Due to free-time constraints and the lack of consistent clear skies, I only shoot with a one shot color CMOS camera. I also have light pollution to contend with from my location. This filter is the perfect solution for my situation. I have been producing excellent images. I have also seen excellent images others have produced using this filter even with a full moon in the sky. It is very expensive for one filter but the cost is not outrageous considering it is actually four filters-in-one.


Game Changer

It's difficult to overstate how significant an impact the Triad Ultra has had on my imaging. I'm not going to lie, it was not an easy purchase; it certainly isn't the cheapest filter out there, but I'm seeing results I would have NEVER been able to get without it. The results on emission nebula is nothing short of stunning, and it's all done without the time or complexity of shooting mono with multiple filters. I'm using it with an ASI294MC, and it's performance with my camera is flawless. The Veil nebula reveals extraordinary color and if far more prominent with far less total exposure time than without the filter. The Eagle Nebula, the North America Nebula, Pelican Nebula, Crescent Nebula, etc are all perfect targets, and will show exceptional detail, depth, and color. As a matter of fact, the data I get with this filter is so good that beyond calibration, stacking, basic color calibration and background extraction, I haven't had to manipulate the images at all. Once the basic routines are complete, I end up with finished products that I am very happy with. If I could give this filter more stars, I would. It's not cheap, but it's been one of my favorite AP purchases.

Andrew L.

The real deal

I used this filter with both the ZWO ASI071MC-P, and with the Starlight Xpress SX-814 Monochrome camera. With the 071, I was able to shoot through heavy light pollution (I had street lights right next to my setup) to test how well it worked in light pollution. The images came through of the Omega Nebula and I was extremely impressed with the details that I was able to get with it, especially through the street lights. The 2nd test was using it as a luminance filter for my narrowband shots with the monochrome SX-814 camera. The detail was again extremely impressive, but I have not been able to get a full narrowband data set as the weather has not cooperated. Looking forward to clear skies to finish getting Ha Sii Oii data to combine with the Triad filter as the L channel. So far, this filter is doing everything I expected and more.

Eddie H.

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: https://www.astrobin.com/389492/?nc=user . 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