TeleVue Nagler 31mm vs Explore Scientific 30mm ?

The new design looks like it would be easy to look through. I ended up removing the mushroom from mine and I love the eyepiece. I really think it is as good as any other 30mm I have ever used.

+1 on the excellence of the 31mm Nagler. I haven't tried the others, though.

Wow looks like Many of you like the TV ep: But Manu of you still haven't tried the ES one. Should I flip a coin to see which to buy?

Well, some have tried the previous incarnation, and it is rumoured to be optically identical (at least as far as glass types, lens configurations, polishing and coating are concerned) even though the baffling, retaining ring and other mechanical aspects may be different.

I'd say: if you have the money to spare, you can't go wrong buying a 31T5 (especially if you can buy one used, which means it will probably not depreciate very much). If you don't, well, then the question answers itself.

We seem to leave out the 31mm Axiom LX. An excellent ep with or without a paracorr. I saw no different between it and the 31mm T/5. Wait there is one, ER 21mm for the Axiom and 19mm for the Nagler, just saying. Oh, and price!

Clear Skies!

I totally forgotten about the celestron Axiom LX. But I think televue is still better right?

We're not exactly "leaving out" the 31mm Axion LX. Compared to the ES, it's basically the same design (or if you can believe ES a very slightly earlier version of the same design) made by the same people in the same factory but in different packaging.

Sure, the polishing quality might be different, the coatings might be different and the internal baffling might be different, but I'd be hard pressed to actually see a difference from what little I've seen to date.

So axiom and es is around the same design?

The Celestron Axiom LX (not the old "Axiom" without LX), ES 82° and Meade 5000 UWA share the same basic design and are all made in the Jinghua Optical Company factory in Kunming, yes.

So basically everything is the same except the brands and coatings?

My final decision is I'm going for Televue Nagler 31mm type 5

I've just received my 30mm Explore Scientific 82° N2.

No first light yet (well, only daytime first light, but trees don't tell you everything), but some observations:

Subjectively, as close to a 31T5 in look and feel as it gets (probably not a coincidence). With small eye pupil, just the same lateral colour with the eye improperly placed when looking at the edge, suggesting there will be exactly the same ring of fire effect (not that it matters). Eye relief is pretty tight for a 30mm eyepiece, just like on the T5 (the stated eye relief is larger than the usable one because the eye lens is concave), but for me it's perfect. In daylight it's fairly easy for me to see exactly where the exit pupil is (in my f/4 StarBlast the exit pupil is a lot larger than my daytime eye pupil!) and I can say that I just have to press my face into the eye cup and it's perfect. 10/10 for comfort.

Coatings (using the "cap the eyepiece on one end and see what diffuse light comes back your way" on both sides) is evidently not up to T5 Nagler standards, let alone Ethos standards (the difference with the 21mm Ethos, despite its many groups, is quite striking). My guess is that the coatings aren't as well matched to the different indices, i.e. some corners were cut there compared to the absolute best. Coatings remind me a bit more eyepieces like the T2 Naglers or the Meade 4000 UWAs. Actually, probably not as effective as far as transmission is concerned as the the 34mm Meade 5000 SWA that it replaces.

But I digress. It's got four groups and eight air-glass transitions, so a difference between 0.5% reflectivity and 0.25% reflectivity will only amount to a total difference in transmission of 2%, so I'm not overly worried (though it's probably inevitable that bright object in view would produce a tad more veiing glare). In fact, comparing to the Meade SWA and looking at multiple reflections of dust particles on the outer lenses, low angle scatter is probably very well controlled, and that's probably more important.

Focuser in-travel required is (thanks to the absence of that conical section on the 31T5 which prevents the 31T5 from being seated deeply in the focuser but allows a very large field stop without any vignetting) surprisingly middle of the road, nothing like the 31T5. Good thing for Paracorr owners. I think that's the convenience that is costing us 1mm of focal length and a tiny bit of field stop size if you compare with the 31T5.

As the eyecup design is now flawlessly executed, the only "what on earth were they thinking" feature now seems to be the shiny 2" barrel with 2" filter threads and very narrow and shiny retaining ring for the field lens. From looking down into the capped eyepiece and looking through the uncapped eyepiece with light sources around, it's a fairly safe bet that it can still cause the (rare) bright off-axis object glare issue than plagued the direct predecessor (in particular, there's the hard to fix edge of the retaining lip that's just as shiny and directly abuts the field lens).

They'd be much better off anodising the barrel black (and possibly flat-black-painting the lower section that will never contact filter threads) and adding a fairly narrow blackened retaining ring like TeleVue does on the 21mm Ethos just above the field lens. I'd gladly pay for it (in fact, I have a half destroyed M48x0.75mm retaining ring from TeleVue but the threads are different enough for me to fail to install that on the ES. So much for standards and US companies knowing how to convert 0.75mm per thread into tpi correctly).

From daytime observation and comparing with a 26T5, I'd say that its design will probably perform almost exactly like a 31T5, but with slightly less pincushion distortion (although that never bothered me in the 31T5 at night). But design isn't everything; execution also matters, and it's clear the price difference between it and the 31T5 isn't just lining Al Nagler's pockets.

For me, though, it's pretty good, and just at the price point I wanted it.

At substantially less than even second hand 31T5s, that's quite a feat, but more about that later.

Summary: as close to a 31T5 as you'll get for the price as far as I can see (WARNING: has not seen stars YET). Not actually identical, and no match (as far as attention to detail is concerned) for Ethos or Pentax XW eyepieces (given the price, though, and the almost legendary performance of 31T5 and Pentax XW eyepieces that's a big "Duh!").

Sixela,

Thanks for the info and I am anxiously waiting for your full report.

It's not that I need more glass but at that price and if they perform much like what I read... Well why not go for a few. :rollgrin:

sixela,

great explanation; your experience shows.

btw, I was in your neck of the woods a couple of years ago. It's a wonderful place , but, many lights and people everywhere. How are your skies there?

VERY light polluted. Less so if I drive an hour to stand between the cows, but even there light domes are a dime a dozen. It takes me two hours and a half to drive to decent skies and five hours to drive to really good ones.

Ah well.

I should add (for completeness' sake) that there's a second retaining ring closer to the eye lens that is also shiny, but I doubt it's relevant (the specular reflection from light that can reach the ring in my opinion probably can't reach the exit pupil anyway.

Wow looks like Many of you like the TV ep: But Manu of you still haven't tried the ES one. Should I flip a coin to see which to buy?

If you are going to flip a coin, play it safe and go with Nagler.

So basically everything is the same except the brands and coatings?

My final decision is I'm going for Televue Nagler 31mm type 5

Nigel,

If you can't do a direct compare, then I think this is your best bet. You'll pay more, but I think you'll be getting the best unit. The 31mm Nagler is really an amazing eyepiece. The other brands might be as good, or they might not; but I don't think they'll be better.
There must be some reason that the 31mm is the one everything else gets compared to. If I had to get rid of all my TV eyepieces, this would be the last to go, and even then they'd have to pry it from my fingers. For me, it's in the "Legendary UWA" category, along with the old Meade 14mm UWA.

Of course, I've been wrong before! :o

If you do decide to go the TV route, be aware that it does require a bit more infocus as I recall, so some scopes will/may not come to focus without some modification.

Notice that we are now quibbling over small degrees of quality between the two, if any. I say save your money and get the ESs. Your money will go further.

Were there any detailed head-to-head comparisons shared?

I think in the absence of methodical A:B comparative data, it's premature to conclude that differences between the two are "small" in degree.

I bought a 30mm ES 82 (still awaiting first light, unfortunately) over a 31mm Nagler Type 5 mainly because (a) it was cheap on sale, (b) I find it hard to detect on-axis image quality differences between *any* long focal length, lowest power eyepieces (very different than high power/short focal length eyepieces IMO) and © I've used the 31mm Nagler a gazillion times at club star parties (borrowed) but have never looked through an ES 30mm, and wanted to try something new.

Here, specifically, is what I'd like to see compared:

1. Lateral color
2. Rectilinear distortion (day and night)
3. Field curvature
4. Tone
5. Correction for edge of field astigmatism
6. Comparative comfort (eye relief, visibility of field stop)
7. On-axis image quality
8. Fit and finish
9. Relative value

If the weather cooperates I plan on borrowing another CNer's 31mm Nagler and first lighting my 30mm ES on Saturday at our first seasonal club star party and indulging my curiosity. If it works out, I'll share what I learn. If there's already a comparison of the two eyepieces with respect to these criteria, I'd love to give it a read.

Regards,

Jim

[quote name="jrbarnett"]
Here, specifically, is what I'd like to see compared:
[/quote]
I'll have a bite. The only caveat is that it's all daylight usage, so it sweeps a lot under the rug (the eye accommodates for quite a bit of field curvature for daylight targets, the eye pupil is restricted making the modified StarBlast eyepiece torture bench a benign scope, etc.).

[quote]
1. Lateral color
[/quote]
Appears to be the same as in long T5s (with the same sensitivity to eye placement in daylight usage). I expect the same ring of fire at night, but I haven't seen it yet.

[quote]
2. Rectilinear distortion (day and night)
[/quote]
Less. I guess the eyepieces are closer to zero angular magnification than the 31T5 is. Very noticeable in daylight use (but I used a 26T5 to compare).

[quote]
3. Field curvature
[/quote]Seems quite flat for the time being (like the 31T5), but let's see at night. The eye knows all too well what you're looking at in daytime usage.

[quote]
4. Tone
[/quote]
Holding the eyepiece to a white wall, more neutral than the 26T5 and even the 16T5 (which is pretty white for a Nagler). Very similar to the 21mm Ethos.

[quote]5. Correction for edge of field astigmatism[/quote]
In a Paracorred Starblast, quite good compared to the 26T5, but of course the restricted eye pupil makes it easier on the eyepieces by lengthening the effective f/ratio well beyond f/4.6.

My guess (working from memory) is that it's slightly better than the behemoth Meade 5000 UWA, but conditions aren't favourable to really decide.

[quote]6. Comparative comfort (eye relief, visibility of field stop)[/quote]
Feels like a 26T5 (probably no coincidence, since they've abandoned the "innovative" eye cups at last and reverted to something which Just Works and has for ages).

I'd guess that makes the eye relief a tad smaller than that of a 31T5, but for me it's perfect. The 26T5 is stated to have 16mm of eye relief but the usable eye relief is't that large because of the concave eye lens, and this eyepiece shares all these traits. I have the eye lens at the exit pupil if I just press my face lightly on the eyeguard, so it's just perfect for me.

[quote]
7. On-axis image quality
[/quote]
I'm not sure you can say anything relevant for such eyepieces. In slow scopes, they're bound to perform well (essentially completely scope diffraction limited), and in fast scopes, at least my eye aberrations overwhelm anything an eyepiece can generate. In other words, there's no reason for me to prefer the 31T5; stars are going to appear just as ugly as with the naked eye anyway once my eye pupil is dilated.

[quote]
8. Fit and finish
[/quote]
External fit and finish superb, but coatings aren't as good as on T5s (and certainly not as on an Ethos). Coatings appear a bit more reflective but they don't "glow", so I don't expect a lot of low angle scatter, just somewhat less transmission (but we know from Brandons that's not that important) and perhaps some extra veiling glare (there are more chances for some of that light to creep back to the eye).

There are some shiny surfaces outside (retainer for field lens is a lip on the shiny barrel rather than a nice rounded and flat black retaining ring like on the 26T5, though I seem to remember it wasn't as wide on the 31T5) and inside (the one that's probably most troublesome is a grooved surface in the middle that is obviously anodised and reflects back to the eye both from the eye side and the scope side if you have a cap on the other side). My guess would be that it's going to be plagued by the exact same occasional "problems" as its predecessor, i.e. a rare problem with some extra veiling glare if you have very bright sources just outside of the view that might make it irritating for lunar observing, but for my scope type that's really not relevant.

Reflects a "what can we get away with if it costs less" attitude rather than the more paranoid attention to baffling in the Nagler (which in turn is just healthy paranoia, and nothing like the real paranoia Pentax or Zeiss can sometimes display).

[quote]
9. Relative value
[/quote]
No night time use, but I bet the eyepiece is good and daytime performance was really impressive for the price I paid. It's certainly light years ahead of the Meade 5000 SWA it replaces.


[quote]If there's already a comparison of the two eyepieces with respect to these criteria, I'd love to give it a read.[/quote]

I know what I wrote isn't perfect --daytime testing is only limited in what it can tell you, but hey, some imperfect info is better than none, right?

Were there any detailed head-to-head comparisons shared?

I think in the absence of methodical A:B comparative data, it's premature to conclude that differences between the two are "small" in degree.

Jim

You Sir are correct. I made my claim on anecdotal evidence and a few snippets of actual testing of the EP as presented by various folks that have handled the new line of EPs. My mistake.

I will say this, even if they are not equal to the vaunted Televue Nagle Eps, but in fact very close, I will still see them as desirable over the TVs at close to a third of their price. Half when not on sale. It’s that magic balance between FOV, quality and cost that ES has met that has made a believer out of me. Bravo ES!

Now make a 2.7mm and a 21mm 82 and I will be in heaven, in more ways than one.

Cheers.

It’s that magic balance between FOV, quality and cost that ES has met that has made a believer out of me. Bravo ES!

Cost is always a factor. One reason I buy TeleVue products is because I can afford them. I am not wealthy, but comfortable. Here is my saying: 'there may be eyepieces as good as TeleVue, but there are none better'. Now, this applies across all their lines. There are individual Plossls made by other vendors better than a specific TeleVue Plossl, and so on. However, their best are the best and their not the best are almost the best.
GeneT

Thanks Alexis. That's marvelous.

Very helpful.

Regards,

Jim

I'd be interested to know if at least my daytime observations are consistent with what you see; two pairs of eyeballs are a better judge than one...