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Using OPT's TRIAD Ultra Quad-Band Filter Under Extreme Light Pollution

Updated: May 20

The Triad filters from OPT and Radian Telescopes have quickly become popular among amateur astrophotographers who image from their light polluted backyard. Because our apartment does not have any outside space, we never had any interest in this filter as 100% of our images are taken from the desert. Well, we recently moved away… and this might be about to change!

Oceanside Photo & Telescope decided to send us the newest version of their Triad filters, the Triad Ultra Quad-Band filter to try out so that we could actually use our telescope from the backyard.

What kind of images can we really get with it?

TRIAD Ultra quad band filter review
Scroll to the bottom to see our full video

las vegas balcony with no view on the sky

As you may have seen in one of our recent videos, we have finally moved out of our apartment!

If you’d like to know why and even follow us on a house tour, watch the video by following this link.

The bottom line? We can finally image from home. This is something we've always wanted to do, but that was simply impossible in the past thanks to our useless view from our tiny balcony which you can see on the right...

The house we moved into is on the other side of Las Vegas, but still within the extreme Bortle 9 light pollution zone.

Besides the few times we used a smart telescope like Stellina and the EVscope, we have never imaged from the city before with our regular astrophotography rig. Being used to our desert skies, it was now time to learn how to fight light pollution.

The Triad Ultra narrowband filter can be attached to any one-shot-color camera, including DSLR cameras, and was designed to allow amateur astrophotographers to take deep sky images from any light polluted area. It can also be used as a narrowband Luminance filter for monochrome cameras. We will try this out as well later in this review!

In this article, we will put the Triad Ultra filter to the test under the most extreme possible conditions to see if it really is worth the price: From a Bortle 9 zone, on a full moon night, and with several nearby neighbor and street lights.

We will be imaging two targets: The Orion Nebula (for a total of 20 minutes) and the California Nebula (for a total of 6.5 hours).

Disclaimer: The Triad filters are made by OPT and Radian Telescopes. As most of you know, we have a partnership with OPT since last year. This article was not written to blindly push sales on the Triad filters but rather to demonstrate the results you could expect with it from a light polluted backyard.

You can also watch us try the Triad Ultra for the first time on video on our YouTube Channel or by clicking on the video at the end of this post. You will also find a gallery of images taken with the Triad filter which will be populated over time.


Specs & Price

The 2" TRIAD Ultra Quad-Band filter we will be trying tonight is 3mm thick. It is snugged into a 7mm tall ring that is between 1.3 and 2.58mm thick depending on the production batch.

Instead of confusing you with a huge paragraph and seven graphs about all the specifications of the Triad Ultra filter, let's just try to understand how it works in a simple way.

Just like its name implies, the TRIAD Ultra Quad-Band Narrowband filter is… a narrowband filter! You should not expect to get incredible images of galaxies or star clusters using this filter, as those are broadband targets and most of their light will actually be blocked by it.

Instead, the TRIAD filter was designed to be used for photographing nebulae, more specifically emission nebulae.

Table showing the Full Width/Half Measure and Peak Transmission for each channel fo the Triad Ultra filter
Table showing the Full Width/Half Measure and Peak Transmission for each channel fo the Triad Ultra filter

The Quad-Band version of the TRIAD filter combines four band-passes:

  • Hydrogen-Beta

  • Oxygen III

  • Hydrogen Alpha

  • Sulfur II

The Sulfur II bandpass is new to the TRIAD Ultra, and was not included in the previous version (the TRIAD Tri-Band filter).

How much does it cost?

The TRIAD Ultra Quad-Band filter costs $1,075 at the time of this review.

The Tri-Band version costs almost $300 less at $775. Whether or not the newer Ultra version is worth the extra money depends on you.

Opening the box the TRIAD Ultra comes in


How to attach the TRIAD filter to a camera?

As we showed you in our video, attaching the TRIAD filter is pretty straight forward, but beginners may wonder where it's supposed to be screwed in. In short, it simply screws in to an adapter (that most likely came with your telescope), which one depends on what size you picked for the filter. You can also attach directly to a coma corrector, as we'll show you below.

For this example, we will be using our cooled OSC camera and our 8" Astrograph telescope. We will also be using an extender as well as a coma corrector.

If you have a similar setup as ours:

  • Attach the extender to the camera

The size of the extender varies depending on how much back-focus you need for your setup. We suggest taking a look at our "How to attach any camera to a telescope" tutorial post and video.

  • Attach the coma corrector to the extender

If you have a fast telescope like ours (f/3.9), you will need to attach a coma corrector between the camera and the telescope. Screw it in directly to the extender you just used.

  • Attach the TRIAD filter to the coma corrector

Carefully attach the filter to the coma corrector. Obviously, make sure to not touch it with your greasy fingers...

  • Attach it all into the telescope's focuser

Finally, simply insert it into the telescope as you would without a filter.

Correct attachment for the Triad filter using a coma corrector and extender with asi 071MC
Correct attachment for the Triad filter using a coma corrector and extender

Shooting the Orion Nebula with the TRIAD Ultra Filter

Tonight's main target will be the California Nebula, a faint emission nebula in the constellation Perseus that is not very easy to capture.

But before we do that, let's first slew the telescope to the easiest of all nebulae: the Orion Nebula.

I decided to spend just a few minutes on M42 to see what to expect from the filter. I knew for sure that because of M42's brightness, I'd have no problem seeing it in my test shots so it would be a nice first target for a test run.

Here is a single shot of 30 seconds on the Orion Nebula using the ZWO ASI 071MC and the Triad Ultra filter. As you can see, it looks pretty promising!

The Orion Nebula with the TRIAD ultra filter, single shot 30 seconds

Sadly, I did not do enough math on that night and did not reach the perfect back-focus for this setup. We almost always use our ASI 1600MM camera for imaging deep sky objects and did not double check how much spacing was needed for the 071MC (it's actually the same for both, 55mm, but I didn't count the filter wheel). As you can see, the stars on the edges are elongated and not pinpoint.

Below is the final image, fully processed of the Orion Nebula.

During processing, I had no choice but to crop the elongated stars on the edges out and so only kept the nebula itself. Either way, for only 20 minutes of total exposures, from the city, on a full moon night, this is an incredible result.

The Orion Nebula 20 minutes using the Triad Ultra Filter

Attempting the California Nebula with the TRIAD Ultra Filter

Now, enough playing around. It is time for a more challenging target: The California Nebula.

Make sure to check out our full post about the California Nebula to learn more about this object, we also plan on imaging it again in the future from the desert without the filter and add it to the article.

Right off the bat, I was surprised to see the nebula appear so easily on the few test shots we did while trying to center it exactly how we wanted it. Before launching the series of photos, I decided to take off the filter and, after refocusing properly using our Bahtinov Mask on Rigel, took a 5 minute shot of the nebula. I then re-attached the filter, refocused and took another 5 minute shot of NGC 1499. Below, you can see the comparison between the two!

We're not sure why the single shot without the filter has darker edges, most likely due to the incorrect back-focus, but if we look at the visible gas, which is what matters here, the difference is night and day.

NGC 1499 - 5 minute single shots without and with the filter. Use the arrow to see the difference!

Processing the data was fairly easy. I've heard from several sources that it could be tricky to process frames taken with the Triad filters, but I simply followed my usual workflow (which you can access here), and it worked like a charm. The only thing I wish I did was to take flat frames. In 4 years of Astrophotography, we have never used flat frames for any of our images. We usually don't feel the need for it, but in this case with this specific camera, we had to go through a bit of work on Lightroom to take care of some unwanted dust and other artifacts.

Here is our final image of the California Nebula, a total of 6.5 hours of exposures taken with the ZWO ASI 071MC camera and the TRIAD Ultra Quad-Band filter. Visit our full post about the California Nebula to see a version that only has 4 hours of total exposure, the difference is pretty interesting!

The California Nebula astrophotography with the Triad Ultra Filter and ASI 071MC camera


Gallery of images taken with the Triad Ultra Quad-Band filter

We will update this gallery with more images over time. All of the pics below are taken from our Bortle 9 backyard.

Final Thoughts

Doing astrophotography in a Bortle 9 zone is a challenge, and you usually require 10, 20, or 30+ hours of data for a single target in order to get a nice-looking image. We find it mind blowing that one could achieve a result like the one above in just 4 hours under an extremely light polluted sky… and a full moon.

We are in love with this filter, and are kind of sad to know that it is now time for galaxy season. We hope to be able to use this filter again when some of the greatest nebulae start to rise in Summer. Below you will find a gallery of images taken with the TRIAD Ultra filter. We will do our best to update it with more pictures taken from our backyard over time.

Make sure to follow us on Facebook, Instagram, Twitter and YouTube to stay up to date with our work!

Clear Skies,

Galactic Hunter

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