View Full Version here: : 35mm pan vs a 31mm nag in a 12" dob
04-01-2011, 09:09 PM
hi all. i am looking at buying a good low power eyepiece for my 12" dob. i was looking at 35mm pan and the 31mm nag. i am after some reviews on this as i don't know anyone who has these to try out. i have read a lot of reviews on the 35mm pan. i am leaning more toward the 35mm pan as it weighs less and a little cheaper.however i also have read that i mite need a Paracorr with the 35mm.
04-01-2011, 10:28 PM
The 35 pan yields a 7.1mm exit pupil in your F/5 dob which is something to consider. If you're not perfectly dark adapted, you might have problems with shadowing caused by the secondary mirror. The TFOV is 1.6°.
The 31 Naglar produces a 6.3mm exit pupil which won't cause any problems, with a slightly wider 1.7° TFOV, so I would save my pennies and purchase it instead of the 35 panoptic.
At F/5, either eyepiece will be fine without a paracorr, you can look up reviews of each eyepiece, but the amount of coma one finds objectionable varies from person to person so I recommend trying the EPs if possible before committing to a purchase.
05-01-2011, 08:07 AM
Note coma is a linear off axis aberration so the 31mm Nagler with 42mm field stop diameter will show more coma than a 35mm Panoptic with 38.7mm field stop diameter in the same telescope. Also you will likely see the coma more easily with the 31NT5 since it will be magnified more. A Paracorr really does clean things up nicely but at the expense of weight.
Consider also the 26mm Nagler with a 35mm field stop diameter as it is almost the same size and has the same weight as the 35P but it does have less eye relief if that is an issue.
Have a look at http://www.televue.com/engine/TV3_page.asp?id=28 and you will see that the 35P and 20NT5 are in the same Parfocal group and are a nice combination. (The 20NT5 also combines well with the 31NT5 even though not parfocal with it. You can also see (column F) that the 26NT5 and 17NT4 are also almost parfocal. This also means the paired parfocal eyepieces mentioned have the same Paracorr setting on the tuneable top.
One last option is the 21E which has a 36.2mm field stop diameter but weights slightly more than the 31NT5. Note you can get the 35P+20NT5 for a few dollars less that the cost of the 21E.
The 35P will give you a 'large' exit pupil but if your sky is not too bright it will be fine. Also if you are only using it as a low power scanning/finder eyepiece it will also be fine with the larger exit pupil. The 31NT5 is one of the best eyepieces Tele Vue has made and is a fine performer in many telescopes and you do get that beautiful 82 degree apparent field. The 35mm Pan is also a very good eyepiece with excellent eye relief and if you prefer 68deg apparent fields would be the eyepiece of choice.
Note if you wear glasses when observing the 35P will be more comfortable and you will be able to see the entire field more easily. Again see also the Tele Vue specs for eye relief figures.
Whatever you choose, enjoy!
05-01-2011, 09:24 AM
I use the Pan 35 in a 12inch f/5 Dob and find it sooooo nice to use.
Personally I find the Panoptics 'easier' that the Nags, just more comfortable on the eye. I've never had issues with shadowing (seeing the secondary) with this combo either, but do with a 40mm eyepiece I have, I'd expect 35-36mm is about the limit.
05-01-2011, 11:59 PM
Weight may be an issue with both of these. I cheaped out and bought the 35mm Pan and its a nice eyepiece indeed. Not up with the 31 Nagler, but so much cheaper. I do find it has barrel distortion at f5 which is a tad annoying when sweeping star fields, but really gives those big globs some extra depth!
I find that it is much better used with a paracor (but so is every eyepiece).
Given that we will not see the sky again this side of astrofest, you can try mine out there :lol:
08-01-2011, 12:14 PM
i was looking too at the 21mm ethos as i was more interested in getting a large fov the 21mm at 1.4^ * 70 mag. i just thought the mag mite be to much at this fov? looking at the pan and the nag they were around 1.5,1.6 fov and 50 * mag.
any views on this.
any one using the 21mm in a 12" dob? i would like to hear your views too.
i really do wish i could see for my self.
08-01-2011, 06:29 PM
I have not tried the 21E so cannot comment on it's performance but I would think 70x mag is not too high in a 12". The 31N and 20N is a very nice combo but at a greater price. The 20N is small and light compared to the 31N and 21E. Coma seen may be more objectionable in the 21E due to its wider field stop than the 20N. The coma seen in the 31N will be the greatest but less magnified so may actually be more pleasing.
Back to your original question; if you are pleased with 68 deg views get the 35 Pan, but if you crave for a wider field then get the 31 Nagler and add a 20 Nagler later when you can afford it.
Perhaps others with a 21E and have used one in your type of telescope may want to chime in here with some further advice.
09-01-2011, 07:44 AM
I have the 21 Ethos but have not tried it in my 12.5 inch Discovery as that scope has not seen use since the arrival of my 15 inch Obsession.
The 21 Ethos performs great in the Obsession...but it is a monster in size compared to my previous "low power" workhorse the 24 Panoptic.
I like a bit more low power magnification than many but then my skies are not "inky black" either.
09-01-2011, 10:05 AM
We have both a 21E and 35Pan - I end up using both in my 16" DOB. I have a bit of a love/hate relationship with the 21E... For a start it's huge, second it's heavy, third it really shows up the coma with an F4.5 mirror, combination of a wide true FOV and the magnification... so then you need the paracorr - which makes it heavier again - Setting up the DOB with enough counterweight to balance this combo throws it out for any normal eyepiece.
Also for some reason I find it harder to see the full field with the 21E vs the 10E we have - I can't really explain that, except that you have to roll the eye cup down and really get your eye right in there, which just isn't that comfortable.
So lately the 21E has been spending more time in our refractors with the 35PAN doing the find stuff / wide field views in the DOB... However if there is a bit of light pollution or for some objects which demand both FOV and magnification it really does look amazing.
09-01-2011, 06:55 PM
Does the 31mm Nagler have as much eye relief as the 22mm Nagler?
I know it's 19mm for both on paper, but I don't trust any manufacturers eye relief claims.
hello team, having asked the question i thought it best to purchase both eps and find out for myself,the pan and the nag are best compared by suggesting that it is a similiar experience that you get between a 100 deg and an 80 deg eyepiece of the same focal length.
the nag has the edge by having the wider field but you do have to seek it out as it is not readily apparent.in all other aspects they are very close to each other and choice will be a personal one in that regard.....i will keep both as they are both excelent eps.
30-01-2011, 09:58 PM
I like your style qld - can't decide so just buy 'em both. But what about the XW30mm? :) .
i have a 28 ewan a 30 williams a 32 aspheric hyperion a 30 celestron a 30 meade and a 30 explore scientific .......dont want anymore 30's ..besides nags are the go for my 16 and 25 obsessions and if you come to the star party at wiruna you are welcome to try them all
forgot to mention the 30 Andrews sw which i gave away free to a good home .
31-01-2011, 09:16 PM
I've been considering buying the Explore scientific 30mm 82 degree with the new slimmer body - how does it compare to your other eyepieces?
hi i ihink that the es is similar to the pan,with the exception it is bigger and heavier, the optics are good with colour detection of red and yellow stars being more prominent than in the pan.....i put this down to coating differences with that of the nagler, which in my opinion allows more light transmission and thus the image is brighter taking away some of the hue of the colour in those stars.and for the price it is a very good ep, as are the es100 eps of which i also have a couple and as i have said on other posts on iis compared to the ethos range they perform very well...hope that helps......but i would prefer the 31 nag now that i have made the comparison,it has the better field of view by far
01-02-2011, 09:02 AM
Thanks qld. When you say the 31 Nagler has a better fov than the ES30mm, do you mean that the outer field has less aberrations in a fast scope? How does the eye relief compare between those two?
hi i also have a 16 lightbridge which is at f4.5 which is the fastest i have tried these eps at. i found that a paracor was needed in the 4.5 and the 4.7 obsession but not in the 25, there is more of the field to see in the 31 Nag than the others and that includes the 35 Pan and es30 the image with the 31 nag is sharp to the edge of field whilst the others show some coma at the edge which is dissappointing if you are conscience of it otherwise you wouldnt notice it.
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