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TeleVue Nagler 31mm vs Explore Scientific 30mm ?

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#51 Benach

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Posted 03 February 2011 - 06:39 PM

Alexis, will make an appointment for that within a couple of weeks ok? I still have the 31mm T5 so you then don't have to compare by heart but it can be done directly.

#52 jrbarnett

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Posted 03 February 2011 - 09:04 PM

Hopefully Saturday, if the weather cooperates.

I'll be running a 4-incher though, and slow-ish to boot (f/8.6), so probably not as good of a test of edge correction as your Dob.

Regards,

Jim

#53 Benach

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Posted 04 February 2011 - 09:08 AM

Jim: won't make it by next saturday. Will be somewhere in March though.

#54 sixela

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Posted 08 February 2011 - 05:21 PM

I've just had it under the stars. Compared it to a 26T5 and to a 21mm Ethos (which makes it harder for me to compare things like veiling glare because magnifications are different).

The scope in use was my resident eyepiece torture bench, aka Starblast with 2" focuser and Paracorr. An f/4.6 system with the Paracorr and an f/4 system without the Paracorr (but at that f/ratio unable to deliver clean stars because of brutal field curvature and coma, so it's only used to test specifically how much astigmatism is added when you subtract the scope aberrations).

A second scope (but used less intensively) was my Paracorred f/4.5 (f/5.1 with Paracorr) 400mm Dob.

Targets were the moon (for checking glare, scatter issues and lateral colour), M45 (for field curvature and astigmatism), the M36/37/38 open clusters in Auriga (for checking field curvature more stringently and for panning to discover what distortions there are) and M42 with NPB (with OIII/H-beta and H-alpha passbands, also to check on lateral colour).

Edge of field astigmatism is fairly well controlled, and only really obtrusive in the f/4 Starblast (where it combines with coma and field curvature but adds fairly obvious astigmatism from 20° from the edge onward). There's also quite a bit of field curvature in that scope but most comes from the fairly short focal length StarBlast.

With the Paracorr inserted, my eye's astigmatism actually dominates over the entire field (the vignetting by the secondary actually makes edge stars look less astigmatic than the centred stars!).

In the f/5.1 system, there is very little edge of field astigmatism, actually not much more than in T5 Naglers though more than at 40° off-axis in the 21mm Ethos (which is really a superb eyepiece).

There is too much field curvature too accommodate in the Starblast-sans-Paracorr, but I have no problem focusing the edge and the centre at the same time in even the Paracorred StarBlast, except when observing M36/37/38 critically (the eye accommodates less easily for different focus than on bright stars, and it takes the f/5.1 system with less field curvature on its own before no refocus at all is needed).

Colour tint is less yellow than in large T5 Naglers, still bluer than the fairly neutral 16T5 and very slightly more yellow than on the 21mm Ethos.

There seems to be little low angle scatter and the moon's ashen glow is actually just as well defined as in the 26T5 and 21mm Ethos.

There is some glare with the moon close to the field stop in the Starblast but none in my 400mm Dob (which is baffled better, and by the looks of it the Starblast's spider vanes are responsible for some of the issues and effects are visible even in the 21mm Ethos). No issues seem to be caused by the ring in the middle which in daylight seems to be a possible source of glare.

Distortion is very well controlled (at least for an 80° AFOV eyepiece). I'd say there is just a tad more pincushion distortion than is necessary to get zero angular magnification distortion but *a lot* less than in the T5 Naglers. Hardly any globe effect is visible when panning. Only the Ethos beats it even though there is actually more angular magnification distortion at the edge of the Ethos (but that's at 50° off-axis instead of 40°).

Lateral colour is well controlled but starts fairly brutally at 7° from the edge (when placing the moon at the edge in the Starblast one end of the moon is a rainbow and the other end has no lateral colour at all). When using an NPB filter, stars also only split into a red one and a green one fairly close to the edge -- much closer to the edge than I remember in Panoptics let alone Meade 5000 SWAs. The T5 has the same kind of effect but much closer to the edge, and the Ethos is almost completely devoid of lateral colour except just next to the field stop.

Summary: darn close to a T5. It's very hard for me to evaluate whether the coatings actually cause more veiling glare because of the differences in magnification (and I suspect even 30mm ES vs. 31mm T5 might make it too close to call). A tiny bit more edge of field astigmatism but really insignificantly so in fast scopes because my eye is actually what gates performance. In an f/5 scope, though, I don't think it'd be that easy to see much difference in focus (though star testing should still enable you to see which is the 31T5). If one thing is different, it's the lateral colour that's absent from the majority of the field but pops up close to the edge.

Light years ahead of the 34mm Meade 5000 SWA it replaced.


For the price I paid, it's a killer eyepiece.

#55 mgb

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Posted 08 February 2011 - 08:00 PM

Sixela,

Thank you for this great report... Greatly appreciated.

#56 Paul R.

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Posted 09 February 2011 - 06:21 AM

Had them both for usage in a f5 scope. The 31N was far superior..better contrast, sharper, very little pincushion distortion compared to the 35P..etc..smaller exit pupil..

Plainly I could *see* things in the scope's field in the 31N that I couldn't see with the 35P. A no brainer here..

I have news for you though..the 21E for the most part outperforms BOTH of them..with the obvious exception of slightly smaller actual FOV and diminished eye relief.

#57 sixela

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Posted 09 February 2011 - 08:27 AM

Depends on the object.

A 21E is better to see detail in objects that in a 30ES/31T5 are well above the contrast threshold for detection, but if you have very large but very faint objects you do need larger exit pupils to increase the chance of detection.

That's why I have both a 30ES and a 21E.

#58 robinsondd

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Posted 31 May 2012 - 07:07 PM

Came across this thread will looking at the Nagler 31T5.

So Nigel, how do you like your EP?

#59 Scanning4Comets

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Posted 13 December 2012 - 04:20 AM

Wow!

Two excellent reviews Alexis! Both day and night versions were a nice read. I did a Google search on the 30mm ES N2 82 and ended up here reading ALL OF IT!

:waytogo:

Very informative indeed.

#60 Damo636

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Posted 13 December 2012 - 06:44 AM

Had them both for usage in a f5 scope. The 31N was far superior..better contrast, sharper, very little pincushion distortion compared to the 35P..etc..smaller exit pupil..

Plainly I could *see* things in the scope's field in the 31N that I couldn't see with the 35P. A no brainer here..

I have news for you though..the 21E for the most part outperforms BOTH of them..with the obvious exception of slightly smaller actual FOV and diminished eye relief.


Great reviews!

I also had both and did my own comparison. I kept the Nagler simply because the ES (latest N2 version) had completely unuseable filter threads! I found them so close at f5 its barely worth mentioning the differences. I don't know if its my eyes, but the 31 Nagler has the worst pincussion distortion I have ever seen! The ES to my eyes has a much flatter field. I have no doubt had the ES been in 100% working order, the Nagler would have been rehomed! I do love the big Nagler though & have no desire to part with it, unless maybe for the 25mm ES 100°, if it ever comes to pass that is ;)

#61 Jon Isaacs

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Posted 13 December 2012 - 08:02 AM

I don't know if its my eyes, but the 31 Nagler has the worst pincussion distortion I have ever seen! The ES to my eyes has a much flatter field.



A flat field means that the entire field is in focus at the same time. In my experience, the 31mm Nagler has a very flat field.

Pincushion distortion is something else all together.

Jon

#62 Damo636

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Posted 13 December 2012 - 09:27 AM

You are correct Jon, I'm getting my aberrations mixed up :scratchhead: The 31 Nagler has a flat field but, for example, panning through the Milky Way, its as if the field is bending, almost like looking through a fishbowl! It doesn't bother me as I don't tend to observe in this manner, but I can see how some have experienced a feeling of motion sickness as a result. I found the ES to be much better in this regard!

#63 Scanning4Comets

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Posted 13 December 2012 - 04:12 PM

What is the exact weight of the 30mm ES N2 82? I was thinking of selling my Orion 38mm Q70, and getting a 30mm ES N2 82 for better edge correction and a smaller exit pupil.

Are they 3 pounds? :bigshock:

Cheers,

#64 Damo636

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Posted 13 December 2012 - 04:43 PM

Its slightly heavier than the 31 Nagler Mark....

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#65 Scanning4Comets

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Posted 13 December 2012 - 04:54 PM

That's not too bad at all! Just over 2 pounds would be ok! Thanks for putting the 30mm on the scale Damo! I thought they were 3 pounds....but just over 2 is fine !!!

I'm thinking of selling up my 38mm Q70 and grabbing one of these!!! I love the eyepiece pron. :^)

Cheers,

#66 Djarum

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Posted 13 December 2012 - 05:14 PM

Good comparison. Thinking about getting the ES to replace my AT Titan II 40mm. The ES should give me similar FOV at more magnification.

#67 csrlice12

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Posted 14 December 2012 - 08:46 AM

Do y'all think there is a market for "astro eyeglasses" that are smaller and inset quite a bit closer to the eyes? My optometrist says can do pretty much anything and he works with these tiny eyeglasses that I would bet could easily be altered to make it easier to get the eye in closer to the eyepiece... He used Zeiss coatings on my newest pair of regular glasses when I told him I was into astronomy.


Wow, a doctor who does what he can to help his patients??? That's a rare thing these days....congratulations!

They would probably be great for those with astigmatism, but they'd have to be by prescription only....

#68 Starry eyes

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Posted 15 December 2012 - 01:59 AM

One important feature that the Nagler 31mm can make use of is the Dioptrix. I have a Dioptrix on my 31mm so I don't need eyeglasses for my visual use. I find that the combination of the Paracorr II, 31 Nagler, and Dioptric is a real treat to use on my F4.5 scopes. I don't know if anybody else has this complete system so well dialed in.

#69 bherv

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Posted 15 December 2012 - 09:56 AM

I had a chance to do a side by side comparison of the two. I found that both are excellent eyepieces. One thing I found surprising was that despite
the slightly higher magnification of the ES 30 it actually seem to have a larger total field of view. I was using a 17.5" f/4.5 with a Paracorr for the test. The ES 30 is definitely a great value at 1/2 the price of the 31 Nagler.
Barry

#70 ohioalfa64

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Posted 20 December 2012 - 01:59 PM

My ES 30mm 82-N2 arrived today. Yes, it weighs in at 2 lbs 4 oz. It is the size of a large Hermes Egg. It is huge to hold in your hands. Its like softball size.

Can't wait to see it in my Dob (12.5" f4.0), paracorred of course (to f4.6).

#71 Scanning4Comets

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Posted 21 December 2012 - 02:21 AM

I had a chance to do a side by side comparison of the two. I found that both are excellent eyepieces. One thing I found surprising was that despite
the slightly higher magnification of the ES 30 it actually seem to have a larger total field of view. I was using a 17.5" f/4.5 with a Paracorr for the test. The ES 30 is definitely a great value at 1/2 the price of the 31 Nagler.
Barry.


What's the 30mm ES 82 like w/o a Paracorr @ F/4.7? From your review Alexis, you said you could see field curvature.
I detest FC and can put up with a bit of coma more.

#72 csrlice12

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Posted 21 December 2012 - 09:55 AM

My ES 30mm 82-N2 arrived today. Yes, it weighs in at 2 lbs 4 oz. It is the size of a large Hermes Egg. It is huge to hold in your hands. Its like softball size.

Can't wait to see it in my Dob (12.5" f4.0), paracorred of course (to f4.6).


The old, nonwaterproof version weighs in at 3.08lbs, but what an eyepiece!

#73 Scanning4Comets

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Posted 06 August 2013 - 05:31 PM

Here I am back at this thread again !!!!

Deciding between another 34mm ES 68 or a 30mm ES 82. Don't know which one to get this time !!! :thinking: :idea: :hmmmm: :scratchhead:

#74 JustaBoy

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Posted 06 August 2013 - 05:42 PM

Hi Markus,

Well, I know that you like your 100° eyepieces, and since 82° is closer to 100° than 68° is, then you could get the 30/82.

Simple <g>

Also, since you have had a 34/68 in the past, and you know how you like to try new things...

Simple again!

Anything else I can help you with, Sir?
:stooges:
-Chuck

#75 csrlice12

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Posted 06 August 2013 - 06:20 PM

Why not get both the 34 68* AND the 30 82* and remove all doubt?






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