Nagler T6 question

[West End Wendy]

Hi,

I'm a newbie to the forum – been into stargazing for about a year now and recently upgraded from a pair of binoculars to a telescope (Skywatcher ED100), which I'm extremely happy with.

When it came to buying eyepieces I decided to adopt the approach that I would rather have one top quality eyepiece than lots of cheap or mid-price ones. With that in mind I bought an 11mm Nagler T6, of which I could find no negative comments at all on the net.

A couple of months down the line and this eyepiece both impresses and frustrates in equal measure. On the positive side, it is superbly built, and the views through it are every bit as spectacular as I was hoping. However it is extremely fussy when it comes to eye position, and I get frequent black outs - a situation seemingly exacerbated by the fact that the eye guard appears to be shallower than the eye relief – so that when your eye socket touches it you're already too close.

Do other forum members have any similar experience of this eyepiece or are blackouts with certain eyepieces very much an individual phenomenon? Perhaps viewing comfort will come with more experience in finding the correct eye position?

Thanks in advance for the advice,

Tim

[pvaz]

To me it only happened with large widefield EPs. My Nagler 31mm T5 gave me the same problems. However I now put the eye right on place by instinct. I need to put it inline with the EP axys with my nose brushing the side, to avoid blackouts. My Ethos is much less fussy on that.

Give it another try, if you can't get along maybe you can trade it for something like a Pentax XW (top quality as well, bit smaller FoV but less fussy).

[John]

Hi Tim,

I've owned a number of the Nagler T6's though not the 11mm (I think the 11mm is the only T6 I've not owned in fact !). They are a scaled design, that is the optical configuration of each one is the same, just scaled to deliver the appropriate focal length. They also share the same viewing characteristics including the 12mm eye relief which I found meant that my eye socket needed to be touching the eye cup, but not rammed right into it. I did not experience black outs or other issues but I know those were an issue with earlier Nagler designs (eg: the Type 1's).

I would accept that using Naglers does require some practice and they are not to everyones taste.

You may find the Radian series more comfortable to use.

[NGC 1502]

Two replies have mentioned Pentax XW and Radians. I have 2 Radians and 3 Vixen

LVWs. All these eyepieces share the same 20mm eye relief. Not everyone likes that,

or finds it necessary, but I do find that these are all very easy to use, with no

blackout or eye positioning issues.

I've looked through several clubmates T6 Naglers. Although I found them more

fussy with eye positioning, and noticed the shorter eye relief, I think it's a matter

of what you get used to. The T6s are very compact and sharp to the edge.

But if you really can't get on with yours, they are easy to sell, lots of people

want them.

Best regards, Ed.

Edit : By the way, welcome to SGL !!

[sixela]

They are a scaled design,

The T5 is scaled, but my impression was that the T6 was't a scaled design (otherwise the eye relief would be proportional to the focal length, whereas I've experienced them to be a constant eye-relief series, which by definition can't be a scaled series.)

The difficult bit in the T6 is actually keeping your eye pupil centred over the eyepiece when you look around (by "automatic" compensating head rotation or shift), but it's a skill you usually eventually do acquire instinctively.

[John]

The T5 is scaled, but my impression was that the T6 was't a scaled design (otherwise the eye relief would be proportional to the focal length, whereas I've experienced them to be a constant eye-relief series, which by definition can't be a scaled series.).....

Thanks for that clarification - thats clearly my confusion over the precise meaning of the term "scaled" showing there

[johninderby]

The T6 isn't better than the T5, it's just a different design series for different focal lengths.

This article will give you a good overview of the Nagler eyepieces and the differences between them.

http://www.cloudynights.com/documents/naglers.pdf

John

[sixela]

Thanks for that clarification - thats clearly my confusion over the precise meaning of the term "scaled" showing there

"Scaled" means that you basically just take the design and make a smaller version of it to get smaller focal lengths and a larger version of it to get larger focal lengths.

In principle, you don't change anything else though obviously you'll change the barrel to a standard (1.25" or 2") and may make different choices with respect to internal baffling, how wide you make the lenses and the body, and where exactly you place the focal plane with respect to the eyepiece barrel shoulder.

Yes, that 16T5 Nagler really just is a shrunk version of the 31T5 with the eyepiece focal plane placed somewhere else.

[spaceboy]

I think if you have small very curved glass and you have to look through up to 7 pieces of it you will find it fussy with regards position. I don't think it is so much the "eye placement" as the line of sight through the eye piece from the object. Trying to marry the object with line of light traveling through the glass into your eye on something so small I think is an amazing feat that we take so much for granted with modern optics that we over look the difficulties our ancestors would have faced just to get the same results from their telescopes. I always think of it as looking through a magnifying glass and how you have to get it just right to get the optimum image. An eyepiece I assume works on the same principle but with several magnifiers and correctors. I think to a certain degree the issue is easier resolved with making the lens larger and hence why the said Pentax and radians seem to get away with black outs.

Companies would go out of business is they were to only ever make one model. Be it eye pieces, TV's, Cars you name it. The consumer is always hungry for new this is how we are conditioned by the commercial world. Only trouble is sometimes there are no improvements to make to an old model and so you try to make some thing more compact or bigger in the attempt to keep the money rolling in. A natural misconception can be a new T6 is going to be better than an older T4 but this is not always the case.

I agree the T6 do have their faults but this is why JAPAN (instead of ROC) is labeled on the side to "sell" the EP to you and over look these faults. You will always have someone defend it to the death saying it's a superb eyepiece you couldn't get better but that is until the T7 comes out then that will be the best thing since sliced bread.

It is obviously the price you have to pay for having such a AFOV in such a compact eyepiece. If there were no black outs and the EP weighed in at 2LB then people would complain they are to heavy. Televue just need to try and find the happy medium but that will come with the T7 (no shock as that will make them more money)

[sixela]

I agree the T6 do have their faults

I don't think it's a "fault"; it's just inherent in wide field eyepieces with relatively high magnification (and thus smallish exit pupils) that you'll have more trouble centring the eye pupil over the exit pupil when you actually look around.

It could do with slightly longer eye cup or even a moveable eyecup (à la TMB planetary, Pentax SW or Meade 5000 SWA), at least to my taste (but no two faces are the same!

But that's not really a fault in my eyes, just a minor nit (some other eye guards that will help will even fit the eyepiece.)

[spaceboy]

MY BAD! I should choose my words more carefully. I agree it's not so much a fault, after all they do what they say on the tin. I meant more of a shortcoming associated with the design of the T6's

[John]

...I agree the T6 do have their faults but this is why JAPAN (instead of ROC) is labeled on the side to "sell" the EP to you and over look these faults....

You don't think that this is because the Type 6's ARE actually made in Japan then (like the plossls)

[sixela]

MY BAD! I should choose my words more carefully. I agree it's not so much a fault, after all they do what they say on the tin. I meant more of a shortcoming associated with the design of the T6's

Sorry to be a bit of a nit, but I think it's important for me not to be misunderstood.

My first point is that it's actually inherent in any ultrawide when they become shorter, because when you rotate your eye to look around the field you also move the pupil, at least until you learn to compensate with head movement. There's nothing TeleVue can do about the underlying physics, not even if they decided to make the Ultimate 82° Eyepiece at any cost.

The two ways to assist you to beat the fact your eye doesn't rotate around its pupil are using cues to tell you where your head is, either through shortish eye relief (like on a 16T5) or using a movable eye guard; that way, your peripheral vision of the eyepiece around the eye lens helps you to place your eye correctly.

But the T6 has longish eye relief and an eye guard that's a tad too short to help you place your eye.

But it's all personal; I've heard people complain about blackouts in 5mm Pentax XW despite the excellent eye cup ad th fact that I think Pentax really couldn't have done anything more even if they'd tried.

It's less visible in narrowfields because you don't look around that much, and it's less visible in longer eyepieces because the exit pupil is larger so blackout will occur more gradually if you don't place your eye optimally.

My second point is that it's not because you have problems at first that you'll continue to have them; I can work with T6 Naglers without any issue, whereas I used to feel they were blackout prone at the start.

I also don't think the T6 eyepieces are labeled "Japan" to somehow lure you into buying them despite their "shortcomings". After all, they're i my opinion still by far the best 82° eyepieces in their focal lengths, perhaps bested only by the 16T5 and 20T5 in a *VERY* good barlow (and by the Ethe and Explore Scientific 100° eyepieces if you "forget" the extra field ), and they're actually made in Japan.

[dweller25]

Alexis, I always find your posts informative and it really cracks me up that you come with a health warning - keep the posts coming

Wendy - I have a 5 and 7mm Pentax XW and both blackout if you don't get good eye placement. I think it's a 'feature' of wide angle eyepieces as I don't get it with any of my Orthoscopics.

Oh and welcome to SGL

[West End Wendy]

Thanks for the contributions everyone - very interesting reading.

In the end I'm prepared to put up with the odd blackout for the large FOV, which is not just a needless gimmick or an empty visual spectacle - it actually, rather magically, appears to darken my light-polluted skies. This is, presumably, because the magnification is higher than I would otherwise be able to use to see a given area of the sky.

With the whole of London to my immediate south, this is no mean feat.

Tim

[West End Wendy]

...although I'm really not entirely sure what Televue have against twist-up eyeguards...

[Chris H]

Do you observe standing or sitting? Sitting can make a world of difference not only more comfy but it will help hold your head steady and therefore your eye. Have you tried rolling down the rubber eye guard? I find doing this makes it easier to avoid blackouts and it also makes the eyepiece more immersive.

I have had similar problems with my 12T4 and it took me quite a while to get the hang of holding my eye in the correct place, it is still an occasional problem but the ep is worth it.

[Ags]

This blackout thing - I don't get it with 52-degree plossls, I get it a little bit with 60-degree TS Planetaries, and I get it a lot with a 68-degree Hyperion. I've decided the problem is trying to balance the eye on a blunter and blunter light cone as the apparent FOV goes up. The slightest error in eye placement will cut off part of a blunt light cone, while a more acute cone is less likely to bump into the edge of your pupil.

The problem cannot be solved by eyepiece design. all e.g. 82 degree eyepieces will try to construct a similar cone of light that behaves in basically the same way - the only difference being the aberations introduced by each individual eyepiece design.

I agree with the sitting idea. Sitting has made observing (and using eyepieces) much easier.

[spaceboy]

You don't think that this is because the Type 6's ARE actually made in Japan then (like the plossls)

Hi John

Can I put one question across on this that may get you thinking. What is on the side of a WO UWAN?? and where are they made

SPACEBOY

[spaceboy]

Alexis, I always find your posts informative and it really cracks me up that you come with a health warning - keep the posts coming

Forgive my ignorance but is Alexis not a female name ?

Doh! I see it now

[John]

Hi John

Can I put one question across on this that may get you thinking. What is on the side of a WO UWAN?? and where are they made

SPACEBOY

You will have to help me out that one - it's been a long time since I owned a UWAN

[Nexus 6]

Hi Tim,

I agree with Chris, I have found that I really need to sit when observing, a big advantage to negating effects that will spoil your views. I agree with your idea of going for quality over standard ep's, I wanted to see what the differences were and they quite sudstantial compared to the standard plosll ones I had to start with and I hoped they would stay with me even when I decided to buy a new scope.

The type 6 I have is superb, views through it have given me my best views of all the solar system objects I have observed. I am going for a 13mm type 6 soon, afraid I can't afford the Ethos!

Alan

[sixela]

Forgive my ignorance but is Alexis not a female name ?

Apparently not always; I definitely seem to have a Y chromosome.

[spaceboy]

You will have to help me out that one - it's been a long time since I owned a UWAN

Hi John

William optics USA

They do have a striking resemblance to Orion Meagaview and Skywatcher Nirvana don't they. Some would argue they are the same eyepiece.... but how could this be ? WO UWAN have USA on the side so are they made in the USA ? There is 2 ways this labeling can be read depending on your perception;)

Forgive me if I don't explain myself well in text and have caused confusion. I'm not saying that TV's are not made in Japan I'm just pointing out that having Japan wrote on the side instead of ROC or Taiwan may be suggestive to the new consumer this is of a higher grade compared to other models and that as it's a "T6" by some miracle shortcomings that have been established to 82' design eyepieces may no longer be so much of an issue.

My reply was intended to help Tim look past any misconceptions of pay more get more or better advertising/ labeling and to be aware that all wide eye pieces will suffer the same shortcomings no matter how much you pay. I'm only using TV's as the example due to the higher costs compared to their competitors and Tim asked about a Nagler. Granted you do get better performance regards sharpness etc, but the same inherent shortcomings are present in TV's as would any 82' EP.

When it came to buying eyepieces I decided to adopt the approach that I would rather have one top quality eyepiece than lots of cheap or mid-price ones. With that in mind I bought an 11mm Nagler T6, of which I could find no negative comments at all on the net.A couple of months down the line and this eyepiece both impresses and frustrates in equal measure. On the positive side, it is superbly built, and the views through it are every bit as spectacular as I was hoping. However it is extremely fussy when it comes to eye position, and I get frequent black outs - a situation seemingly exacerbated by the fact that the eye guard appears to be shallower than the eye relief – so that when your eye socket touches it you're already too close.Do other forum members have any similar experience of this eyepiece or are blackouts with certain eyepieces very much an individual phenomenon? Perhaps viewing comfort will come with more experience in finding the correct eye position?

Just for the record I'm also not saying Just because some thing is made in Japan/USA dose not automatically suggest it's better but some may argue this to be so. This is all down to personal preference and opinion which we all have a right to. I'm sure they are the same coatings, materials and are assembled in the same way be it ROC, Taiwan, Japan or USA.

[Rui]

I don't think it's a "fault"; it's just inherent in wide field eyepieces with relatively high magnification (and thus smallish exit pupils) that you'll have more trouble centring the eye pupil over the exit pupil when you actually look around.

I think that those blackout areas that appear on the field of view due to your eye positioning can be considered a fault. In fact, it was because of that that al Nagler invested in new designs. For example the 13mm evolved from Type 1 to Type 6 precisely because of that "Kidney Bean" effect.

Once I had a couple Orion Epic EDII and they also were very sensitive to eye positioning.

Meanwhile, that doens't seem to be related only to the wide fields because the Epics I mentioned are only 55º and the Ethos are 100º and people don't complain about black outs...

Just my 2 cents...