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New TV Nagler vs. 30-year old Plossls

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#1 Mountainwabbit

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Posted 16 July 2020 - 08:36 AM

Hi, I have recently gotten back into amateur astronomy after a 30 year hiatus, and I wanted to pick everybody's brains on my reaction to my recent purchase of a TV 13mm T6 Nagler. I am using a 12" f/5 Newtonian with a TV Paracorr 2 (both new) in conjunction with my circa 1990 TV Plossls. I have started to upgrade the eyepieces, beginning with a 27mm TV Panoptic. That eyepiece blew me away with its overwhelming superiority to the 26mm Plossl that it replaced.

So my second upgrade was the Nagler, and I spent last night jumping from object to object, switching between it and my vintage 17mm and 10.5mm TV Plossls. To say that I was disappointed was an understatement. Of course, the Nagler has a wider AFOV, but that was its only strong suit. On practically every object, one of the Plossls outperformed it. Only with a select few - the Swan Nebula stands out in my memory - did the balance of surface brightness and sky darkening result in the Nagler having the best view.

With star clusters, both globular and open, and with double stars, the Nagler was notably inferior. Sharpness from center to edge was consistent, but never as good as the Plossls. After a few hours of testing, I was completely steamed, and ready to condemn the Nagler to the bottom of my junk drawer.

So I am very aware that this is an atypical reaction the 13mm T6 Nagler, which gets so many glowing reviews. What do people think? Is it possible that I have a lemon? Or was I just approaching this eyepiece with too many expectations?

Thanks in advance for your insights.
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#2 peleuba

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Posted 16 July 2020 - 08:50 AM

So I am very aware that this is an atypical reaction the 13mm T6 Nagler, which gets so many glowing reviews. What do people think?

 

Hmm.  My 13mm NT6 is my most used eyepiece.  Ever.  I have complete sets of the NT6's, Delos and Delites, so it does not get used as much as it once did but I love mine and its an early model.  In my Portaball its my favorite eyepiece for Globular Clusters.

 

 

Is it possible that I have a lemon? Or was I just approaching this eyepiece with too many expectations?
 

 

Maybe a little of both?  Anything wrong with the coatings?  And, is it clean?  Cleanliness is an often overlooked aspect.  If I am looking at the planets, I make sure that the set I am using is clean.

 

Don Pensack would be a good resource for an opinion.  But without being able to examine or look through the eyepiece a lot of feedback that you'll get is mostly conjecture.


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#3 Mountainwabbit

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Posted 16 July 2020 - 08:58 AM

The Nagler is fresh out of the box - not a smudge or speck of dust. I gave the Plossls a thorough cleaning last month, so they are at a disadvantage for cleanliness.

As far as the coatings, shouldn't the Plossls be at a disadvantage there, too? I have read that the technology has progressed a lot over the years.

Edited by Mountainwabbit, 16 July 2020 - 08:59 AM.


#4 SeattleScott

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Posted 16 July 2020 - 09:22 AM

The Plossl are a less complex design so they should have less scatter and better contrast. I had an 8mm TV Plossl that just edged out my 7 Nagler. However the difference is quite subtle, and the wider view of the Nagler allows for framing targets at higher power. That is where the real improvement in the view is. Using it on small targets that fit in the view of the Plossls isn’t taking advantage of the Nagler. The beauty of the Nagler is being able to fit a 20mm Plossl field of view but at 13mm focal length.

That being said, if the plossls were clearly sharper, that would be disappointing. I would expect them to just edge out the Nagler for contrast.

Scott

#5 NC Startrekker

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Posted 16 July 2020 - 09:43 AM

I'm with Paul here.  My N13T6 is one of my most used 1-1/4" eyepieces.  Absolutely love it.  I'm not sure what was going on during your observing session with it.


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#6 Mountainwabbit

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Posted 16 July 2020 - 09:52 AM

@ Scott - I think that with 30 years worth of improvements in coating technology, I was expecting the Nagler to beat the Plossls. That certainly was the case with the Panoptic, which was love at first sight. And while the Nagler's wide AFOV is nice, I couldn't stop nitpicking its lower contrast - I preferred the Plossls' narrower but sharper views even on large objects like the Lagoon and the Veil.

I wish I could have tested the Nagler before buying, but I live in a remote area with more coyotes than people.

Edited by Mountainwabbit, 16 July 2020 - 09:52 AM.


#7 mrowlands

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Posted 16 July 2020 - 09:58 AM

Are you adjusting the Paracorr correctly for the Nagler?

 

Mike R.


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#8 Mountainwabbit

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Posted 16 July 2020 - 10:00 AM

Yep, I even tried different settings than those recommended by TV to see if I could improve it. No dice.

#9 TOMDEY

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Posted 16 July 2020 - 10:02 AM

Interesting! Well, let's see... the chain is object, atmosphere, 12" F/5 Newt, Paracorr 2, eyepiece (17.5 Plossl, 10.5 Plossl, 13 Nagler), eye (L/R), expectation, perception, evaluation. TeleVue's design, build, and quality-control are all without question... World Class Premium. So, there is something in the chain that is profoundly favoring the Plossls over the Nagler.

 

Here are some possibilities: Are you adjusting the Paracorr for each eyepiece? That's important; TeleVue explains that the differential aspect being a bit arcane. Your 10.5 Plossl delivers a 25% smaller pupil than the 13 Nagler; bigger stresses one's visual acuity more. The eye placement is more demanding on the Nagler, both lateral and longitudinal. If you are significantly myopic sans glasses, that could also have an effect/affect (very arcane).

 

It would make sense to get an experienced friend or two over and ask them to chime in. Best would be a ~blind study~, not push-poll. If they're steeped in this stuff (e.g. with the local club), I'll bet they come up with something that explains your strong preference. The quality of the eyepieces is unlikely to be it.    Tom


Edited by TOMDEY, 16 July 2020 - 10:04 AM.

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#10 sixela

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Posted 16 July 2020 - 10:15 AM

Hi, I have recently gotten back into amateur astronomy after a 30 year hiatus, and I wanted to pick everybody's brains on my reaction to my recent purchase of a TV 13mm T6 Nagler. I am using a 12" f/5 Newtonian with a TV Paracorr 2 (both new) in conjunction with my circa 1990 TV Plossls. I have started to upgrade the eyepieces, beginning with a 27mm TV Panoptic. That eyepiece blew me away with its overwhelming superiority to the 26mm Plossl that it replaced.

So my second upgrade was the Nagler, and I spent last night jumping from object to object, switching between it and my vintage 17mm and 10.5mm TV Plossls. To say that I was disappointed was an understatement. Of course, the Nagler has a wider AFOV, but that was its only strong suit. On practically every object, one of the Plossls outperformed it. Only with a select few - the Swan Nebula stands out in my memory - did the balance of surface brightness and sky darkening result in the Nagler having the best view.


For many objects a 10.5mm eyepiece may deliver a more optimal magnification for the detection of object details than a 13mm, and just because it says "Nagler" on it and has 82° AFOV that won't change.

Especially on an f/5 Newt I expect e.g. most medium sized galaxies to look better in the 10.5mm Plössl if you compare it with a 13T6, although fainter outer portions might be more visible in the 13T6.

For large nebulae with a UHC filter, I expect the 10.5mm to lose, but then the 17mm Plössl might beat the 13T6.

Edited by sixela, 16 July 2020 - 10:22 AM.

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#11 Mountainwabbit

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Posted 16 July 2020 - 10:29 AM

@ Tomdey -

I like your breakdown of the pertinent issues. I wish I could have somebody come over to give me an expert opinion, but I live pretty much in the middle of nowhere.

I did notice the lateral eye placement issue last night, and it's the main reason I'm not completely giving up on the Nagler yet. I'm thinking that it might improve with time and practice.
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#12 Jon Isaacs

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Posted 16 July 2020 - 10:44 AM

For many objects a 10.5mm eyepiece may deliver a more optimal magnification for the detection of object details than a 13mm, and just because it says "Nagler" on it and has 82° AFOV that won't change.

Especially on an f/5 Newt I expect e.g. most medium sized galaxies to look better in the 10.5mm Plössl if you compare it with a 13T6, although fainter outer portions might be more visible in the 13T6.

For large nebulae with a UHC filter, I expect the 10.5mm to lose, but then the 17mm Plössl might beat the 13T6.

 

:waytogo:

 

I agree. The most important thing about an eyepiece is it's focal length. It determines the magnification and the exit pupil.

 

To make a valid comparison, the focal lengths should be identical.  10.5 mm to 13mm doesn't seem like a big deal but it's a 24% difference in magnification and a 54% difference in brightness.

 

Jon


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#13 SeattleScott

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Posted 16 July 2020 - 10:55 AM

@ Scott - I think that with 30 years worth of improvements in coating technology, I was expecting the Nagler to beat the Plossls. That certainly was the case with the Panoptic, which was love at first sight. And while the Nagler's wide AFOV is nice, I couldn't stop nitpicking its lower contrast - I preferred the Plossls' narrower but sharper views even on large objects like the Lagoon and the Veil.

I wish I could have tested the Nagler before buying, but I live in a remote area with more coyotes than people.

Technically it was a 7T1 so coatings probably similar, but coatings are really about light transmission, not contrast. Contrast can benefit from anti-reflection coatings, but mainly on bright objects.

Your 27 Pan bested what, a Meade 26mm Plossl? $30-40 eyepiece? Mass produced? The TV plossls are excellent. Before you were comparing premium TV to cheap mass produced stuff. But now you are comparing TV to TV, and contrast is what the plossls do best. You don’t upgrade TV Plossl with Nagler for sharper views. You do it for more AFOV. Sorry but that’s the only benefit of upgrading to Naglers. That and potentially more eye relief, at least for the short FL plossls.

That being said, the Nagler should have very similar contrast to the TV plossls.

Scott

Edited by SeattleScott, 16 July 2020 - 10:58 AM.


#14 Mountainwabbit

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Posted 16 July 2020 - 11:01 AM

No, it was a TV 26mm Plossl.

#15 John Turley

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Posted 16 July 2020 - 11:04 AM

Are you adjusting the Paracorr correctly for the Nagler?

 

Mike R.

Do you really need a Paracorr with a Nagler, especially with a focal length as short as 13 mm.

 

John 



#16 ddegroot

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Posted 16 July 2020 - 11:08 AM

I've used a wide variety of TV eyepieces - Ethos, Nagler, Delos, and Plossls - on a wide variety of telescopes. In my experience, Plossls are at least as sharp as more expensive eyepieces. What you give up, as you point out, is often field of view - and that can obviously be critical for observing DSOs. Nevertheless it has at times disappointed me that an eyepiece that costs four times more might provide only minor advantages - at best - over a Plossl. 

RP Vine of ScopeViews makes similar observations, for what it's worth. 

 



#17 BradFran

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Posted 16 July 2020 - 11:43 AM

You've already received some good advice. It seems strange to me that you see such a large difference. It could well be something is up with your T6. The 10.5mm Plössl is an excellent and sharp eyepiece, but not much sharper than a Nager in my experience. I think comparing a 13mm Plössl to the 13mm Nagler would be more apt comparison. Try removing the Paracorr and do a detailed comparison, it could be the Plössl is playing nicer with how it is set.

 

Another issue is learning to see through the Nagler. It is a very different beast than the Plössl. Since I prefer to observe with glasses, the Nager's wide field becomes difficult, even uncomfortable, to take in. Even in the center of the field, it is a different feeling to find and hold the exit pupil and achieve sharp focus. Once you are used to the Nager, this will likely improve. Many prefer Naglers strongly after getting used to them.

 

Also, I find the 26mm Plössl superior to the 27mm Panopic on axis with tac sharp stars, but the Panoptic is an excellent eyepiece which outclasses the Plössl off axis and has a more pleasing and engaging presentation.


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#18 MartinPond

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Posted 16 July 2020 - 11:45 AM

I like to consider theories that make

   almost all contradictory observations true.

 

The eyepiece is not the last stop..

What if:  there was a little bit of cloudiness,

  in the lens or the vitreous, of the viewer's eye?

That would easily explain how a wider field seems

   to have lower contrast.  More glow from the wider

   light. 

You can have a cloudy lens...it takes a lot to have

  it declared 'cataract'.  Floaters and cloudy fluid

  are common, too, with advancing age, and persistent. 

 

You can try fancy pills (that B&L stuff), or just eat a lot of

  spinach pie and greens.  that sometimes makes a difference.

 

A true Abbe (45 deg) or RKE (43 deg) should look even cleaner

   than the Plossl.  Of course, how narrow can you tolerate?

  There are also awesome  60 degrees eyepieces.. 


Edited by MartinPond, 16 July 2020 - 11:46 AM.

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#19 Shorty Barlow

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Posted 16 July 2020 - 11:55 AM

My guess is that it's something else in the light train that's causing this. 

 

med_gallery_249298_10131_359681.jpg

 

For a long time the only Nagler I owned was a 16mm T5. Recently I upgraded my 6.7mm ES to the 7mm T6 Nagler. I was so impressed with it that I got the 9mm and 13mm. The 13mm gets a lot of use for rich field in my small refractors. I really can't fault its sharpness or clarity. 


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#20 Steve Cox

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Posted 16 July 2020 - 11:59 AM

I'll agree with the OP here.  Before the Ethos were introduced, I had a set of T6's from 13mm down to 5mm, and I had mixed feelings with them.  I found the older T4's much clearer with less scatter, and much better about getting out of the way and allowing me to enjoy the views more.  The 13T6 I liked but it did not equal the views I got through my newer vintage TV Plossls, and on planets especially I found the views through the T6's soft by comparison to the Plossls.  Once I moved from Naglers to Ethos, that all changed.


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#21 mrowlands

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Posted 16 July 2020 - 12:18 PM

Do you really need a Paracorr with a Nagler, especially with a focal length as short as 13 mm.

 

John 

I do, especially on a manually driven scope.  But I also know some people who don't feel the need for a Paracorr at all on an F5 scope.  Go figure.

 

Mike R.



#22 Mountainwabbit

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Posted 16 July 2020 - 12:22 PM

@ Martin - the vitreous humor suggestion is very interesting. Mine is terrible, and has been my entire life. Some of my earliest memories are of staring at the maze of retinal fibers that I always see when looking at the daylight sky.

#23 BradFran

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Posted 16 July 2020 - 12:38 PM

I found the older T4's much clearer with less scatter, and much better about getting out of the way and allowing me to enjoy the views more.

You could be right. My favorable views of the Naglers were mostly through the older versions.



#24 MartinPond

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Posted 16 July 2020 - 12:59 PM

@ Martin - the vitreous humor suggestion is very interesting. Mine is terrible, and has been my entire life. Some of my earliest memories are of staring at the maze of retinal fibers that I always see when looking at the daylight sky.

One thing that can filter out (in your optic cortex) anomalies is binocular vision

   ...not necessarily binoculars..it could be a bino-viewer.  If the disturbance is in

   one eye but not exactly duplicated in the other, the optic cortex will figure out the

   best(sharpest, most even) piece and the view is fixed.   Same for floaters.

 

Haze (in the eye) is helped a little with green or red-leaning filters.

A trick I found only recently for thin clouds or daylight fog is to use an

  an eyepiece with small, somewhat even Chromatic aberration.

  It plucked seals out of the fog that were totally invisible with

   Plossls  or the Paradigm-ED, using a multi-coated Ramsden (homebrew).

    Also popped some of Jupiter's moons

   out of a cloud.   The fog/cloud chromatics even out across the spectrum, but

   not with a distinct edge...a little red/purple fringing.  The cortex

    jumps on this, finding the critter/object by the edges, and reducing the CA

    with perhaps edge-detection.    There is a lot going on in the noggin.

    A 'fixed-fine-CA' filter would be great  for all EPs.


Edited by MartinPond, 16 July 2020 - 01:02 PM.


#25 hoof

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Posted 16 July 2020 - 01:01 PM

I'll agree with the OP here.  Before the Ethos were introduced, I had a set of T6's from 13mm down to 5mm, and I had mixed feelings with them.  I found the older T4's much clearer with less scatter, and much better about getting out of the way and allowing me to enjoy the views more.  The 13T6 I liked but it did not equal the views I got through my newer vintage TV Plossls, and on planets especially I found the views through the T6's soft by comparison to the Plossls.  Once I moved from Naglers to Ethos, that all changed.

Ditto.  Back when the T6's were relatively new, it was clear to me that the T6's (and Meade equivalents) weren't quite as good as a plossl (or orthos, and supermonos).  Again, it makes sense, fewer elements, doesn't need to be corrected out to the edge (optimizing for one aspect of an eyepiece often degrades another aspect), etc.  However, a slight (and I do mean slight) degradation in the middle of the view always seemed like a good trade-off for the awesome wide field views in fast telescopes.

 

That said, when I got the 13mm Ethos back in 2008(ish), my sentiment changed.  The Ethos is much closer (IMO) than the Naglers were in terms of matching the simple eyepieces.  It was visually superior to my 11mm T6 Nagler in a slight, but noticeable way.

 

This does not take away from the T6's (or any Nagler), it's just my observation that the gap between that-generation of ultra-wide eyepieces and simple eyepieces.  The gap has closed noticeably, with the wide-fields that have come out more recently.  The T6's are awesome, and still one of the most compact ways to get 80 degrees+ views of high quality.


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