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
  • Usable on telescopes up to f/2 speed!
  • Photo Credit: Ross Clark
  • Sale
  • Regular price $1,075.00

In Stock
Free Shipping
Add to Wishlist
Already have gear? Trade it in for cash or new equipment.

Accessories Added

OPT Telescope Expert

Want Help?

Ask Our Telescope Experts


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.

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.


Filter ShapeRound
Filter Thickness3mm
Filter TypeTriad
Free ShippingYes


  • 2-Inch Triad Ultra Quad-Band Filter
  • Filter case
Customer Reviews
4.9 Based on 9 Reviews
Write a Review Ask a Question
  • Reviews
  • Questions
Thank you for submitting a review!

Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Filter Reviews:
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.

patrick r.
United States United States
Best Purchase i have made for bang for your buck! Literally makes your backyard an epic place to do emission nebula photography.

This filter changed everything and now i don't have to travel to a dark sky to shoot all night but rather can keep my rig setup and ready in the backyard and just untarp it and shoot. The contrast and colors that just pop out with a stf autostretch are incredible. A great filter for brilliant photos and also for outreach. Only thing is i wish i had gotten this larger 52mm size vs the 2inch size so if i upgrade to fullframe chips it would cover without any vinette. The filter seems expensive but it is so worth it and will be your favorite piece of equipment! I have def got my money's worth out of it these 8 months. I get so much more integration time with this filter having my backyard rig that the images are 100x better than before. Im blown away at what it can do for a color camera. I shoot 10min exposures and it seems to work well.

Frederick Z.
United States United States
New to Astrophotography

I just retired and now want to engage in a lifelong ambition - astrophotography. Sebastian at OPT understood what I wanted and guided me in identifying the equipment that would best address my ambitions and grow with me as I grew in experience. OPTs expertise made it easy for me to assemble compatible components to put together a first class astrophotography system. I will continue to do business with OPT!

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.