TeleVue Nagler 31mm T5, 17mm T4, 12mm T4, 9mm T1, and 5mm T6 Review

By: Vlad Fedosov


I have some very good memories from my early days of getting into astronomy in the late 1990s to early 2000s. I used to be a member of the astronomy club in Sacramento, CA and would go to the dark sky star parties at Blue Canyon in the Sierra Nevada mountain range. It was here that I was able to first experience the TeleVue Nagler. I saved up my pennies while going I was in college. From what I can remember had the 31mm, 22mm, 12mm, 5mm, and 3.5mm Naglers. At the time the Naglers where the king of the hill with a massive 82° field of view(FOV). Recently I got a set of Naglers as part of telescope package and I was very curious as to how I would like them after a 15-year break from them. Let’s take a look at the Nagler 31mm T5, 17mm T4, 12mm T4, 9mm T1, and 5mm T6 and how they perform by 2019 standards in the age of the 100° eyepieces.


In the early spring of 2019, I attended a star party at a somewhat dark sky site of the Rose City Astronomers in Stub Stewart State Park. That night I had my 16” f/4(Swayze mirror) dob out. It was galaxy season and I decided to leave my regular set of Explore Scientific(ES) 100° FOV eyepiece and grab the set of Naglers to relive some old memories. This star party was the primary observing session where I took notes on the individual performance of the Naglers but I have used them fairly extensively the previous few months with a Takahashi FS-128 as well.

The night started out a bit cloudy at Stub Stewart. This was not too bad as this was my first time setting up and trying to use the ServoCat/Argo Navis goto on my dob. By the time I got the goto up and running(which worked amazingly the entire night) the sky was 100% clear. Transparency was good that night with seeing that was certainly up to the task of observing a list of deep sky objects that was primarily comprised of galaxies. I’m currently working through the Herschel 400 list form my light polluted back yard with my electrically assisted astronomy(EAA) setup. Since most of the objects on the list are hardly visible visually to not visible at all with the c8HD that I’m using given the conditions I’m making a separate list to follow up observations from a dark sky site with the big scope of the more interesting looking objects.

Since I was setup next to a few other folks we also compared views of my 16” to an Obsession UC 15” and a 12” dob of m51, m81/82. Overall it was a really great night of observing and the overall impression that I got from the Nagler line is that they mostly just get out of the way and let you see what the scope has to show. The contrast was good to very good with all of them and they are no doubt plenty sharp enough for deep sky object observing(DSO).
Here are some specific notes on the individual eyepieces that I made that night:
31mm – The “hand grenade”. Well, what can I say about a legend? The 31mm is certainly a very, very good low power eyepiece. Stars are nice pinpoints(you do need a coma corrector in a fast dob. My f/4 16” certainly showed plenty of coma with just the eyepiece) and the view is very easy to take in. Blackout was not bad at all and eye position is not very critical. Contrast is some of the best I have seen in a wide field eyepiece. How does it compare to my 25mm Explore Scientific(ES) 25mm 100°? I would say that the contrast is a hair better on the Nagler and the edge performance is also better. The FOV is also easier to take in with the 31mm. The immersive FOV of the 25mm is something that I really do enjoy especially with a large dob from a dark sky site.
17mm – Very similar in performance to the 31mm. Which is a very good thing! I honestly do not have anything to add to what I said above. A very, very nice eyepiece. I’m not an eyecup guy at all but you do have a hight adjustable eyecup with this eyepiece by raising/lowering the outer barrel. Not sure why they even include this as the eye relief is not that long…
12mm – Contrast seemed not as high with this one. Not too sure why. Still provides plenty of eye relief and a nice view.
9mm – This one definitely shows its age as far as eye relief. Very tight on that. Contrast and sharpness are very nice though. Because of the eye relief, I did find that I like using this eyepiece the least out of the bunch.
5mm – I have owned several of the short focal length type 6 Naglers over the years. I have somewhat mixed feelings about them. The thing I really like about them is that they still have very nice eye relief for such a short focal length. Contrast and sharpness are also good, although maybe not as good as the 31mm or 17mm. The thing that has always bothered me is that because of the small glass that they use it always seems to me that they don’t have as wide of a FOV. This is just a personal complaint as the FOV is 82° just like the rest of the line.


Is the Nagler line still relevant in today’s day and age of 100°+ eyepieces? Kind of hard to say. The 82° FOV is much easier to take in all at once compared to 100°. I do still think that the 68° eyepieces are the kind of the hill as far as observing comfort goes. My primary set of eyepieces are all 100° FOV but I still own and love using an ES 40mm and 24mm 68° FOV’s as they are just soooo comfortable to observe with. I think where the Naglers excel in today’s market is for the astronomer that does not have the budget for the Ethos line but still wants to stick to the no-compromise(for a wide field eyepiece) performance of TeleVue. Overall if I had to stick to just this set of eyepieces for the rest of my life I would not have very many complaints about it. In fact, I would be quite happy!


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