Denkmeier LOA 21 3D Eyepieces Review at LIGO Gravity Wave Detector

By: Vlad Fedosov


What can I say, I’m a binoviewer fan(see my review of the excellent Binotron 27). In the early fall of 2018, I had plans to attend a 3-night star party at the LIGO gravity wave detector in eastern Washington. For those not familiar with it, LIGO is the most precise scientific instrument in the world. In 2015 LIGO was able to detect gravitational waves for the first time. This was one of the most groundbreaking and biggest scientific achievement of the century. Albert Einstine first predicted them about 100 years ago and believed that humans would never be able to detect them since they are so small. As luck would have it Russ of Denkmeier Optical offered me a chance for me to “test drive” his L-O-A 21 3D eyepieces. I saw LIGO as a fitting place to test these binoviewer eyepieces, as Russ had managed to create something that is totally new and groundbreaking in amateur astronomy. There are very few people that can make this claim. I was very curious as to how the view of some of my favorite deep sky objects(DSO’s) would change. The L-O-A 21 3D eyepieces are a 21mm 65° eyepiece pair that can be used with any binoviewer to create a 3d effect while viewing DSO’s. Let’s dive in and see what 3d astronomy is all about!


After a 4 hour drive to eastern Washington, I arrived at Horn Rapids County Park that was reserved by my astronomy club for the weekend. I proceeded to setting up camp and my two scopes that I had for this outing. The first to get setup was my Stellarvue SV4 LOMO APO. Next was my 18” Dob. This was my first time at this campground. Once night fell I, was eager to get observing. It was quickly apparent that the sky was not super dark there since we were near the Tri-Cities area with a fairly large light dome to the south-east. This was kind of a letdown as my brain associated driving far with very dark skies(this was about twice as far as our normal dark sky star party sites. I then reminded myself that the reason I was here was to check out the LIGO gravity wave detector! As a nice bonus, I even had some new astro toys to check out!

Let’s cover the basics of the eyepieces first. LOA 21 3D eyepiece set comes with one regular eyepiece that goes into the left binoviewer slot, and the “array” eyepiece that goes into the right slot. The array eyepiece has an “N” and “F” on the barrel. What these are for is to change the perspective of the object that is in the center of the FOV. If you have the “N”, for near, facing you, the object will appear in the foreground of the stars around it. When you have the “F”, for far, facing you the object will appear in the background of the surrounding stars. With my first look through the eyepieces I found the eyepieces very easy to use with exceptional eye relief. There was no blackout noticed as you move your head around and the view is very easy to take in at once. I think that even eyeglass wearers will not have an issue seeing the entire FOV.

One thing that I immediately liked about the LOA 21 3D eyepieces is that the view is actually very natural looking. Before I used them I had a concern that the 3d effect would be synthetic appearing in nature. You can definitely tell that there is depth to the field with the stars that surround the object ether appearing in front or behind the object being observed(depending on the N/F setting) but it is not an overwhelming effect that looks fake. This is kind of hard to describe and something that one has to really see for themselves. The view looks just like you would expect the object to look like, with just with a nice extra pop of 3d in the surrounding stars!

A few of the most memorable views with the LOA 21 3D eyepieces was of the Dumbbell nebula(M27) and of little known open cluster NGC 6802(picture attached that I took at home with my EAA setup). Both objects displayed an impressive 3d effect with the LOA 21 3D eyepieces. NGC 6802, in particular, looked spectacular in the 18” having the open cluster be in the background, with the two double stars in the foreground. I imagined the double-double being the headlights of a semi truck with the star cluster as bugs splattered on its grill. I did try the eyepieces on Mars just to see what it would look like, and the view was not too much different from normal as there were not many stars around it. Overall I found that the 3d effect was the best on smaller DSO that has a decent amount of surrounding stars. For instance, when I looked at the double-double cluster(NGC 869) in the 4” APO the entire FOV was filled with the pair. There was some separation of one cluster looking closer than the other but this did not do much for me as to me I imagine them being at the same distance in space. But you definitely can get a new perspective on more or less any DSO you like.

On the second day, we went to the LIGO site that’s about 6 miles from the campground. It was amazing to see the detector in real life. We were part of a tour that was given by one of the scientists that helped develop the hardware for the detector as a grad student at CalTech. She was a wealth of information and obviously has a lot of passion for the physics field. One thing that surprised me is how many people were there for the tours. There must have been a total of at least 50 people there. I would not figure that a physics experiment would draw such a crowd. In fact, they are getting so many visitors that they are working on constructing a visitor center. Good to see that there is so much interest for Physics(I guess there are more of us nerds out there then I thought)!

On the second/third nights, I did more viewing with the 3d eyepieces. The eyepieces worked great in both my 4” APO and my 18” Dob. The only “issue” that you do sometimes run into is if a bright star hits the edge of one of the arrays it will double or create a slight flare. In real use, this rarely happens as most DSO’s don’t have stars that are bright enough around them. From what I could tell the eyepieces are about as sharp as my d21’s and certainly sharp enough for DSO work. Contrast also seems to be on par with the d21’s. I did not notice a significant difference in brightness/contrast in the array eyepiece vs the regular one.


Overall I had a really good time with the LOA 21 3D eyepieces! They definitely provide a new and refreshing view of some of your favorite DSO’s. They are recommended to be used under a dark sky. I believe that they would have been even more amazing had I been at our normal central Oregon dark sky site. As a closing remark, if you do not have a chance to try these before you buy a really good way to get these is as a set of 3 eyepieces. You buy the LOA 21 3D eyepiece pair and a second regular LOA 21. That way you are covered for the more immersive deep sky views with the optical array eyepiece and have the regular pair for planetary/other regular observing. I think that Russ has definitely brought something new to amateur astronomy with the LOA 21 3D eyepieces and I would recommend anyone that enjoys binoviewing give them a try!