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Nice review, I used to have a set of Naglers and I regret selling them. I didn't own any of the ones you reviewed, but I did own the 22mm TeleVue Panoptic and I agree wholeheartedly that thing was amazing. You really can tell that Televue does indeed care about their eyepieces the build quality is top notch and very solid. They also hold their value well. Cheers!
  • Orion777 [Mark Gemmell]
  • 12/10/2022 08:55AM
Hi Jack!
Thanks for the comments and reply. I agree about the 22mm TeleVue Panoptic. It's def a special eyepiece in it's own right!
I will probably get another one down the road if I see a nice used one. Cheers to you as well Jack!

I have the 17mm Nagler type 4 and it most certainly does require a coma corrector in a fast dob. It performs well enough with one in my 12" f5 but the in-focus requirement is such that it doesn't come to focus with a paracorr in my 16" f4.5 with a low profile focuser and I'm not about to cut the truss tubes for one eyepiece. That said, its overall performance relative to contrast, resolution and light throughput is quite good but you have to use a paracorr with it to get the most it can deliver in a fast scope. I did expect it to perform better even without the paracorr but it's not well-corrected enough to do so with a fast light cone.
That said, I enjoyed your review of the type 4 naglers...
  • Orion777 [Mark Gemmell]
  • 12/14/2022 08:49AM
Hi Rod,

Thanks so kindly for your comments. All true as you said! I've read quite a few of your reviews as well and I thoroughly enjoyed the ones I did read! Clear Skies to you!

  • Orion777 [Mark Gemmell]
  • 12/14/2022 08:51AM


I meant to say "Forum Posts", lol.

Horses for courses, as they say. I had a 12T4 (new) for my f4.7 dob, and it was my workhorse. I *loved* the Instajust, coupled with the massive eye relief of the T4 design because I like to wear my glasses (combo of presbyopia and astigmatism). I would use my “earlier generation” prescription lenses, and have no fear just pushing up against the insta-justed set point at perfect focus/field stop (i.e no kidney beaning)…. I regret selling it to get the 13 Ethos, frankly (well, sorta, I LOVE the 13E - but that’s another thread). Why? Because now keeping my glasses on is more challenging, and if they come off, I have to fiddle with my Televue astigmatism corrector.

I never did “race” them, but shortly after I got the 13E, I had an opportunity to get my stock Orion mirror swapped for a 250mm f4.5” Zambuto, straight from the man. - also a topic for another day… but wow.

I would LOVE to still have my 12T4, but can easily see the Instajust and potential for Kidney beaning to be a huge issue for those viewing “naked” and floating.

I bought all of the Type 4 Naglers. The 12mm is tight for Eye Relief when wearing my spectacles. The 17mm is better but still a little tight for ER with glasses. The 22mm is the best for ER with my glasses, and is a very comfortable eyepiece. In your review you seem to be conflating Field Curvature with Coma, but they are two entirely separate Aberrations. I do not notice either Aberration in my F10 ACF SCT or my F8 APO with these eyepieces. The Type 4's are great with Dioptrx that I use, but the 12mm does show kidney beaning / blackout a lot more than I would like. If only my 31mm Type 5 had of been a Type 4, I would have enjoyed it much better, the 31mm is tight for ER. A pity that there were no more Type 4's ever released.
  • Orion777 [Mark Gemmell]
  • 04/22/2023 03:36PM
"In your review you seem to be conflating Field Curvature with Coma, but they are two entirely separate Aberrations. I do not notice either Aberration in my F10 ACF SCT or my F8 APO with these eyepieces."

REPLY - (Taken right from my review):
"This was my first experience with field curvature when using the Type 4 Naglers. It was very strong and distracting. I did not have a coma corrector at the time, so I cannot comment on how the coma corrector would have eliminated the field curvature I was seeing. Younger eyes can accommodate the field curvature....older eyes have trouble focusing and is worse, so the 17mm T4 would be excellent for younger eyes or older eyes if you own a TeleVue Paracorr, or other type of coma corrector. "

22mm Nagler Type 4

"I owned this one for much longer than the 17mm T4. Some field curvature was present, but at the time I owned a 2 inch GSO coma corrector and it eliminated some of the field curvature I was seeing with this eyepiece, but over time it got to me and I also sold this as well. (I detest seeing field curvature in any eyepiece). Some of the FC still remained even with the GSO coma corrector, and it eventually was too bothersome."

In no way am I "conflating Field Curvature and Coma". I am well aware that coma comes from a Newtonian Mirror, (Mostly short FL mirrors). I know EXACTLY what coma looks like. It looks like little "comets" at the edges of eyepieces....mainly long FL eyepieces. I am also well aware about Field Curvature. Field Curvature CAN be focused out. When you re-focus an eyepiece, field curvature goes away when seen at the edges, but then you see it in the center of an EP. If you see FC in the center of an eyepiece, and focus it out, you will then see it at the edges. Coma CANNOT be re-focused and as I said in my review here, I mentioned a "coma corrector" which can eliminate coma. I did not say exactly what I am saying NOW and HERE, but if you read the review and pay will be able tom understand what I said. I also did say that the coma corrector did in fact ELIMINATE "some" of the FC seen in the 22mm Nagler...but not "all" of it, and I eventually sold it off.

I just read the review I did and it "does " say "field curvature" and I mentioned a "coma corrector" right after in the initial review it does appear conflating. I should have worded it better.

Thanks for your comments! It does make sense what you said.

Clear Skies!