The Telescope Authority
Since 1947

Radian Telescopes 2" Triad Ultra Quad-Band Narrowband Filter


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  • 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
  • Usable on telescopes up to f/2 speed!
  • Photo Credit: Ross Clark

Product Details

  • 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.

    Below you'll see an incredible image of the Rosette Nebula taken by Jason Guenzel using the Triad Ultra on the super-fast f/2 Celestron RASA telescope! 

    Jason Guenzel Nebula with RASA and Triad Ultra

    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.

  • specifications

    Filter ShapeRound
    Filter Thickness3mm
    Filter TypeTriad
    Free ShippingYes
  • included items

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

Product Reviews

Customer Reviews
4.9 Based on 12 Reviews
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Filter Reviews:
    Jan S.
    Czech Republic Czech Republic
    The best filter ever

    I am using Quadband filter for EAA with Celestron RASA 8 and APO 130mm a its providing excellent results. Now I can do astrophoto even from backyard in big town with extreme light polution.

    Carl K.
    United States United States
    Fantastic with my OSC

    This filter is expensive, but worth every penny. I only wish I would have purchased it sooner.

    Jon H.
    United States United States
    Agreed! This is a game changer!!

    I don't know what to write that other 5 star reviews haven't written. I heard about the filter on the podcast, but the reviews sold me. I live in the Northeast USA so light pollution and more cloudy nights than clear nights equals limited time to gather data. Four filters saves time and (in the long run) money. I've had this filter less than a week, but some how the astronomy gods have looked favorably on me and I've gotten 4 cloudless nights already. The difference in the raw images and some quick stacks/edits is staggering. Thank you!

    Rod C.
    United States United States
    Every Astrophotographer Should Have This Filter

    This is the best filter I have ever purchased. I use it with a wide field telescope (51 x 250 mm) and Canon EOS Ra DSLR. The images of various nebula's are sharp with great detail even on nights with a fairly bright moon.

    Allen G.
    United States United States
    Triad quad and filter

    I have to type fast before my wife sees the debit. The filter is excellent! I shoot from Long Island, close to NYC. The lights come out clear and sharper then with other light pollution filters. I hope I can use it more before my wife murders me. She can, she’s a nurse!

    Ross C.
    United Kingdom United Kingdom
    Transformational For Light Polluted Skies

    I wasn't sure what to expect from this filter, I had been using a much cheaper Triband filter so was thinking 'how much better can it be?' The answer very quickly become, incredibly! For me this filter has 2 important advantages over triband filters available from many other brands, also available from radian. 1) Having 4 discrete narrowband passes allows for the create of genuine narrowband images, this is basically 3-4 high quality 5nm bandpass filters built in to one, the nebula isolation is incredible. Triband filters tend to have a decent Ha pass in the 7-12nm range but the O3 and Hb pass is usually 1 big pass in the range of 35nm or so. For me this causes a couple of issues. a) You get big stars, especially in your blue and green channels due to the larger pass, this makes post processing difficult as you get less contrast in blue and green as star light floods in. b) The broader bandpass in green and blue allows light pollution in which can also cause you greater issues in post. Also the red channel being a smaller pass lags behind significantly in exposure which again can make gauging exposure times and flat exposure times tricky. 2) Halo's, cheaper filters will give you filters, regardless of anti reflection coatings being claimed, browse Astrobin you'll see many a halo. The fact this filter gave me very few halo's was brilliant it just leaves you with a far cleaner final image and, for me, is the hallmark of a true top quality filter. For the reasons above I've found this filter a genuine pleasure to use, post processing is easier as the data produced by it is clean and naturally more balanced due to the narrow band passes that flow in to red green and blue channels of the sensor. OPT were kind enough to use some image that I took with the filter in the images above and I can say that they are some of the best images I've ever taken. I shoot in Bortle 7 so far from extremes of city centre 9's but still strong enough to struggle with RGB. This filter allows me to shoot any day of the week regardless of moon phase and generate excellent results. For these reasons I think this makes the filter good value for money as it actually increases the number of days that you can image.