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TeleVue 22T4 Nagler v 27 Panoptic ?


NGC 1502

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Hi all.   I’m looking for advice regarding the 2 eyepieces in the title.  They will both give a similar true field with my OO 10” F4.8 Dob.

I realise that both eyepieces would benefit if used with a coma corrector. My question is best answered if you’ve used both eyepieces with a similar F ratio reflector - but without a coma corrector.  I’m aware that the N22 would give a smaller exit pupil with a darker sky background, that both have the same eye relief spec, and I’m fine with the N22 instadjust feature.

My specific question - would both eyepieces perform in a similar manner regarding edge of field performance ?

Thanks in advance, your thoughts appreciated, Ed.

 

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Hi Ed,

I used to use the N22 T4 with the same scope that you use. There was a little coma (scope generated of course) showing at the field edge but it was really not distracting I felt. In terms of astigmatism (eye piece generated) the N22 didn't seem to show any.

Not used a Pan 27 so I've not compared.

The N22 is not everybody's favourite Nagler but I liked it. One of the more comfortable and immersive 82 degree eyepieces to use IMHO.

 

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I previously had a 26mm Nagler and it was superb but I sold it as I prefer the 68 degree field of the Panoptics. There's not really much in it in terms of quality. I never compared them directly but feel that Panoptic just edges it in terms of sharpness across the field and I find the T5s and Ethos/Delos newer designs don't agree with me on the moon (although this is not generally a lunar eyepiece of course). You cannot really go wrong at this quality but I am happy with my choice. The 27mm Pan is quite a bit lighter too - the Nagler 22mm is 50% heavier (680g v 464g) which might be a factor in dob balance.

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I have the 12mm and 17mm NT4s and find them to have too short eye relief to use comfortably with glasses.  Using the 22mm NT4 at star parties, I've found it to be no better, so I've never bothered buying one.  I replaced the 12mm and 17mm NT4s with 12mm and 17mm ES-92s.  The latter are better in every respect except for size and weight.

I used the 27mm Panoptic for 20 years and always found the eye relief tight with glasses.  In fact, I scratched a pair on the exposed eye lens retaining ring once.  I recently replaced it with the 30mm APM UFF which is easy to use with glasses, wider in both apparent and true fields of view, not much heavier or bigger, and sharper to the edge with no field curvature unlike the Pan.  It might be a hair less sharp in the center, but that could also be due to the 10% power difference.  All these observations are at f/6.  All benefit from a coma corrector.

If you don't need to use eyeglasses, the NT4s and Pan would probably be fine for you.  If you're young and still have focus accommodation, you probably wouldn't notice the field curvature either.

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The 27mm is the only one I have not had out of the range, but I know a few on site that would not swap it for anything, saying it is the gem of the range. I have had the 22mm and it was not my favourite Nagler, I have also owned all the Naglers around this focal length. I use Panoptics in my Dob and often without the Paracorr 2 and find I can get on with this. I hate soft focus at the edge in any form, why pay for top quality and accept less than even if coma is scope induced. I personally would go for the Panoptic, an eyepiece that rarely shows up 2nd hand and still about the only on I would add to my collection.

Alan.

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I have all the  Nagler Type 4 EPs: 12, 17 and 22 mm. I find the eye relief more than enough for my glasses, so mileage clearly varies, compared to @Louis D. Eyepieces preferences are highly personal, you will find. The 22T4 is probably my most used of the three, and I really enjoy the views, and find it highly comfortable, and it has bagged me many galaxies and a brace of supernovae. I have used the Nagler 22T4 in a 20" F/4.1 Dob, and was very impressed by its performance at the edge. Some coma was visible, but that was down to the scope, and it didn't disturb me much (that too is highly personal).

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On 16/10/2018 at 00:54, NGC 1502 said:

 

Hi all.   I’m looking for advice regarding the 2 eyepieces in the title.  They will both give a similar true field with my OO 10” F4.8 Dob.

I realise that both eyepieces would benefit if used with a coma corrector. My question is best answered if you’ve used both eyepieces with a similar F ratio reflector - but without a coma corrector.  I’m aware that the N22 would give a smaller exit pupil with a darker sky background, that both have the same eye relief spec, and I’m fine with the N22 instadjust feature.

My specific question - would both eyepieces perform in a similar manner regarding edge of field performance ?

Thanks in advance, your thoughts appreciated, Ed.

 

No, the 68° eyepiece would display less visible coma.

The true field size may be close (the 22 is a hair larger), but the lower magnification of the 27mm would magnify the comatic star images less.

One thing to remember is that the wider the apparent field of the eyepiece, the more visible coma will be to the eye.

Coma has a LINEAR size, which is purely determined by distance from the center of the field on the telescope's focal plane,

but it also has an APPARENT size, which is related to the linear size times magnification.

Ergo, if the field is 1/2 as wide, the linear size is 1/2 as large, but if the magnification is doubled, the apparent size of coma is the same.

That's why coma will appear the same at the edge of a 20mm 80° eyepiece and a 10mm 80° eyepiece.

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