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Nagler & Ethos praise

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#1 Darren Drake

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Posted 09 May 2013 - 03:03 PM

I just read through the Telescopes Eyepieces and Astrographs book on the eyepiece chapter. The spot diagram comparisons on p 519 of the various designs show just how amazingly dominant the Nagler and Ethos designs rule all others on off axis performance. It's not even close for f/5 instruments. Even the Abbe Ortho designs are abysmal in off axis performance by comparison. Of course pretty much all eyepieces that have the smyth barlow element have this type of performance but it was TeleVue who first came up with this design platform with the Nagler series in the early '80's. The Ethos does even better than the Nagler series upon close inspection for the inner 80 degrees. For the Ethos eyepieces the main magic comes from that crazy large highly curved element in the barlow end. That's what makes the 100 fov so sharp and possible. I plan to never sell any of my ethoi eyepieces. They are just to magical....

#2 Starman81

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Posted 10 May 2013 - 08:25 AM

I have only one of each but I do love 'em, especially the Ethos! The Delos, though, is supposedly 'better' than both...

#3 cliff mygatt

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Posted 10 May 2013 - 08:34 AM

I agree, the Ethos are great and I have them all and have not messed with my eyepieces since I bought the Ethos, I truly think my EP "upgrading" is over.

#4 csrlice12

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Posted 10 May 2013 - 09:50 AM

While I would love to look thru an Ethos, to be truthful, even some of the 82* are wide enough I can't take it all in; I'm finding I'm preferring my 68-70* eyepieces more (of course, they're better quality then the ES). The Naglers I have are all T1s, while not the latest and greatest, I'm happy with them. Just picked up the 22 and 24mm panoptics and can't wait to try them out....and outside of possibly the backorderd eyepieces (I'll definitely get the ES 82 4.8mm, not sure anymore on the ES68 24mm and 16mm). I donno, I think I'm just about done with eyepieces unless it's maybe a collector's item a a great price (WARNING: Having one can lead to wanting the set, like the T1s). Maybe that's another reason for me to stay away....like I said, would love to view thru one, but I'm already moving my head around with the 82*s.

#5 DaveJ

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Posted 10 May 2013 - 10:52 AM

While I would love to look thru an Ethos, to be truthful, even some of the 82* are wide enough I can't take it all in...


As I mentioned in another thread, there's far more to the Ethos than mere field width. The clarity of view, for lack of a better description, is why I purchased mine. Of course, that gigantic AFOV provides a spectacular borderless image. I have been able to pull out detail in obscure objects that my Naglers have missed completely.

#6 Starman1

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Posted 10 May 2013 - 11:17 AM

If you look through a 50 degree eyepiece, your eye sees the whole field easily, and you can shift your gaze from left edge to right edge
without moving the pupil of your eye so far that it misses the exit pupil of the eyepiece.

When you step up to 68 degrees, moving your eye from left to right does move it away from the exit pupil slightly, so that looking left causes the right edge of the field to darken. No one notices, because you're not looking there and if you look back, your eye moves into the ext pupil and you see the edge fully illuminated again. A lot of people think this is intuitive and easy. And, if the Delos is an example, it's easier to make a focused-to-the-edge design with a 68-72 degree field.

At 82 degrees, though, this technique no longer works. You can only see the edge of the field all the way around with peripheral vision and if you look all the way over to the left edge by merely moving the eye, the entire right side of the field goes dark. So you have to learn a slightly different way of looking at the left side of the field: you roll your head around the pupil point of your eye. In other words, you keep the pupil of your eye stationary and roll your head over to look at the edge. Do this a little while and it becomes normal. People who use progressive eyeglasses typically have less trouble with this. Because the edge
of vision is somewhat distorted with progressives, you learn to move your head to follow your gaze instead of just moving your eye.

My first 82 degree was a difficult-to-use design, and I had some "teething" problems with learning to use it. When I replaced it with a better design 82 degree, I was already used to using the 82 degree field so had no additional problems.

Now, go to 100 degrees and the issue is the same only more critical, because when you roll your head to look left, you're still not looking at the edge. The edge is WAY out there. Think of it this way: your gaze is a spotlight and the field of view is a big stage. If you focus on where the spot is illuminating the stage, you won't be seeing the rest of the stage. So it is with the 100 degree eyepieces. Normal eyes can see the entire edge of the field with peripheral vision, but to see the edge with direct vision, your head is rolled 45 degrees or so over from looking straight in at the center.
Now, I was already used to 82 degrees when I got a 100 degree eyepiece, so it didn't require learning how to use it--I already instinctively knew how.
But picture a lot of newbies going from a 50 degree to a 100 degree eyepiece and thinking the technique they used for the 50 degree eyepiece would work on the 100 degree. Whoops. And so some people who have obtained a 100 degree eyepiece have abandoned them and gone back down to 68-72 degree eyepieces, which work similarly to the 50 degree. Instead of learning how to use the 100 degree.

Are they right? What's the advantage of the 100 degrees?
1) More objects in the field with the object in the center. This is especially true of galaxies, where fields of view can actually be crowded. I can look up there, and over there, and down in that corner, and the images are good enough I don't have to bring the objects to the center of the field to examine them.
2) in an undriven scope, the object takes a lot longer to drift out of the field.
3) it means a higher power can be used and still see the entire object. With 82 degrees, my favorite eyepiece was a 17mm. Now it's a 13mm 100 degree, and the field is a little larger, but with a lot more power, so the background sky is darker and the object is larger. Larger object with darker background = better contrast.
4) In my scope, a higher power eyepiece has a large enough TFOV I can use it as a finder eyepiece. So I can find and view the object without changing eyepieces. There are nights the only eyepiece I've used was my 13mm (140X).
5) the eyepiece just feels "unblindered". The edge is so far out that when you're examining an object in the center you're not even aware there is an edge. Finally, an eyepiece close to the old idea of a "picture window" into space.
6) I can own and use fewer eyepieces. When I owned 50 degree eyepieces, I had about 20 different focal lengths (and a couple barlows). Then, with 82 degree eyepieces that got cut to 9 focal lengths and a barlow. Now, with 100 degrees, I'm down to 6 focal lengths and I no longer use a barlow. And one of those focal lengths is probably going to go because I don't need or use it.
I used to step up in power only a little because stepping up made the field so much narrower. Now, stepping up in power by a lot doesn't shrink the true field so abruptly so I can have bigger gaps between magnifications and not miss the powers in-between. I can have 1.3 degrees, 1 degree, 2/3 degree, 1/2 degree, 1/3 degree and the field size progression is reasonable while the magnification jumps are large (that last one is 304X, which, in my 12.5", is as high as I need to go even
for double stars and planets).

So is it worth the while of someone who observes to learn to use the 100 degree eyepieces? Well, I think yes, and if that 100 degree eyepiece happens to be an Ethos, it is also sharp to right at the edge, has a higher light transmission than most narrower field eyepieces and also has a better rendition of color to the eye.
When I went from a super high-end 13mm 82 degree to the 13mm Ethos, it was a revelation. This 9-element eyepiece actually had a brighter image than the 7 element 82 degree, better eye relief, better color rendition, a noticeably wider field, LESS scattered light, and was equally as sharp. I added the 8mm soon after, and at first was unimpressed. It turns out that the 228X of the 8mm just presses my luck with seeing a little more. When I finally got an observing session with superb seeing, the 8mm was just about the only eyepiece I used all night on galaxies. And it gave me the lifetime-best image of M27 I've ever seen. I have a link to a picture that looks just like what I saw (only without color):
http://www.flickr.co...11859/lightbox/
See the ropy nebulosity toward the outer ends of the long part of the ellipse? I could see that visually.

For me, at least, the progression from 40 degrees to 50 to 65 to 68 to 82 to 100 (or 110) degree fields has been a relatively straight line, and I think it's a one-way street. I read about state-of-the-art 45 degree field eyepieces these days like I would read about really high-end, hand-made, buggy whips. It's cool that someone still makes them, but I'm not Amish. :lol:

#7 chaoscosmos

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Posted 10 May 2013 - 02:04 PM

Yes, I definitely agree with the idea that having Ethos ep's makes one not really feel the need to get anything better, or feel the need for as many eyepieces. The first Nagler I got, a 12mm type 4, was my favorite eyepiece until I picked up a 13 Ethos, an ep I can't ever imagine wanting to sell. The 12 Nagler immediately became expendable.
Picked up an 8E next and was at first not as impressed, but have realized it's also a very nice and useful eyepiece. I'm planning on getting a 21E and I'll pretty much be set. With the 21E, I have a feeling it's possible I'll have no real need for my 31 Nagler.

#8 Stephen S

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Posted 10 May 2013 - 02:46 PM

I read about state-of-the-art 45 degree field eyepieces these days like I would read about really high-end, hand-made, buggy whips. It's cool that someone still makes them, but I'm not Amish. :lol:


:funny:

Thank you Don for your very detailed discussion. I find your posts incredibly helpful.

I wear glasses when I observe. I had a 13mm Ethos and sold it do to eye relief. Perhaps I should give it another try and include a diopter as part of the set up.

Thanks! Steve S

#9 russell23

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Posted 10 May 2013 - 05:25 PM

Don,

What you are saying makes sense. When I picked up my 14mm ES100 a while back the first thing I noticed was that it seemed pretty natural for me to deal with the 100 deg AFOV, but I am used to wearing glasses and with my glasses I do have to move my head because the edges of the lenses do distort the view somewhat.

Dave

#10 russell23

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Posted 10 May 2013 - 05:31 PM

I read about state-of-the-art 45 degree field eyepieces these days like I would read about really high-end, hand-made, buggy whips. It's cool that someone still makes them, but I'm not Amish. :lol:




:funny:

Thank you Don for your very detailed discussion. I find your posts incredibly helpful.

I wear glasses when I observe. I had a 13mm Ethos and sold it do to eye relief. Perhaps I should give it another try and include a diopter as part of the set up.

Thanks! Steve S


Did you try the 13mm Ethos without your glasses? I was shocked at how sharp my 14mm ES100 was without my glasses at 57x in my scope - which is a 2.46mm exit pupil. I have 1.25 diopters of astigmatism and generally figured I needed an exit pupil less than 1.4mm for the view to be sharp enough without glasses. So the performance of the 14mm ES was very surprising and I suspect the 13mm Ethos would also be usable without my glasses.

Dave

#11 GeneT

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Posted 10 May 2013 - 06:39 PM

to be truthful, even some of the 82* are wide enough I can't take it all in;


This is where I came out. A lot of people love the Ethos. I spent two evenings looking through a 13 and a 21. The view was lovely--but too much. I had to work my eye around the lens to see the edge. For me, the Nagler is just right. I have bought several in the Delos series, and they perform very well on all types of objects. However, they have 72 AFOV, which is adequate, but not as good for me as the 82 or the Naglers.
The market place sorts all this out. Our situation is that we have many excellent choices; we are fortunate!

#12 John Huntley

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Posted 10 May 2013 - 06:52 PM

I don't want to see the edge of the field of my 100 degree eyepieces. The "endless pool of stars" effect is exactly what I'm after :)

#13 Paul G

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Posted 10 May 2013 - 07:01 PM

I don't want to see the edge of the field of my 100 degree eyepieces. The "endless pool of stars" effect is exactly what I'm after :)


Same here. M13 nearly fills the fov of the 13 Ethos in my 10" Mak; the view is spectacular, feels like I'm flying through the cluster.

#14 JimMo

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Posted 10 May 2013 - 09:07 PM

I don't want to see the edge of the field of my 100 degree eyepieces. The "endless pool of stars" effect is exactly what I'm after :)


Same here. M13 nearly fills the fov of the 13 Ethos in my 10" Mak; the view is spectacular, feels like I'm flying through the cluster.


+3 Why would you ever want to focus on the field stop?

#15 FirstSight

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Posted 10 May 2013 - 10:08 PM

I don't want to see the edge of the field of my 100 degree eyepieces. The "endless pool of stars" effect is exactly what I'm after :)


++1

#16 Stephen S

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Posted 10 May 2013 - 10:09 PM

I read about state-of-the-art 45 degree field eyepieces these days like I would read about really high-end, hand-made, buggy whips. It's cool that someone still makes them, but I'm not Amish. :lol:




:funny:

Thank you Don for your very detailed discussion. I find your posts incredibly helpful.

I wear glasses when I observe. I had a 13mm Ethos and sold it do to eye relief. Perhaps I should give it another try and include a diopter as part of the set up.

Thanks! Steve S


Did you try the 13mm Ethos without your glasses? I was shocked at how sharp my 14mm ES100 was without my glasses at 57x in my scope - which is a 2.46mm exit pupil. I have 1.25 diopters of astigmatism and generally figured I needed an exit pupil less than 1.4mm for the view to be sharp enough without glasses. So the performance of the 14mm ES was very surprising and I suspect the 13mm Ethos would also be usable without my glasses.

Dave


Good question. I did not. I think I really need to give the Ethos another try. I assume the 13mm is a good place to start (to be used in my NP101). Time to start saving up for the 13mm Ethos.

Thanks! Steve S.

#17 turtle86

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Posted 10 May 2013 - 10:21 PM

I don't want to see the edge of the field of my 100 degree eyepieces. The "endless pool of stars" effect is exactly what I'm after :)


Same here. M13 nearly fills the fov of the 13 Ethos in my 10" Mak; the view is spectacular, feels like I'm flying through the cluster.


+3 Why would you ever want to focus on the field stop?


Not to pile it on, but put me down for a +4. I seldom need (or want) to see all the way to the field stop either. Most of the time I just like the effect of the eyepiece getting out of the way.

#18 mountain monk

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Posted 10 May 2013 - 10:45 PM

+5

Dark skies.

Jack

#19 turtle86

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Posted 10 May 2013 - 10:59 PM

For me, at least, the progression from 40 degrees to 50 to 65 to 68 to 82 to 100 (or 110) degree fields has been a relatively straight line, and I think it's a one-way street. I read about state-of-the-art 45 degree field eyepieces these days like I would read about really high-end, hand-made, buggy whips. It's cool that someone still makes them, but I'm not Amish.



:funny:

Of course, the Brandonites and Orthonites might not approve! :lol:

#20 ibase

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Posted 11 May 2013 - 11:09 AM

Why not have the best of both worlds? Have 100, 82, 80, 72, 70, 68, 66, 60, 55, 50, 45, 40mm EP's and enjoy all of them. :grin: (And yes, I don't look to the edge of the 100, the extra field at the periphery of vision is a bonus)

Best,

#21 Scott in NC

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Posted 11 May 2013 - 11:27 AM

I read about state-of-the-art 45 degree field eyepieces these days like I would read about really high-end, hand-made, buggy whips. It's cool that someone still makes them, but...


I'm going to have to agree with this statement wholeheartedly! :waytogo: It's good that there are plenty of choices out there, especially so that people who really like these have the option of acquiring them, but they're definitely not for me.

#22 mayidunk

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Posted 11 May 2013 - 01:14 PM

I don't want to see the edge of the field of my 100 degree eyepieces. The "endless pool of stars" effect is exactly what I'm after :)

I'm with you on that, but I also realize that seeing the view encircled within the field stop is very important for some people.

I recall reading someplace that it has to do with how a person's brain perceives what it sees. Some people need to have the fixed frame of reference that a visible field stop provides, while others don't. IIRC, for people who need to see the field stop, it isn't so much a preference as it is a need! For them, viewing without the field stop causes their brain to become distracted enough that they are unable to really settle down and enjoy the view.

Apparently, this truly is a case of different strokes for different folks!

#23 Paul G

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Posted 11 May 2013 - 01:23 PM

I recall reading someplace that it has to do with how a person's brain perceives what it sees. Some people need to have the fixed frame of reference that a visible field stop provides, while others don't. IIRC, for people who need to see the field stop, it isn't so much a preference as it is a need! For them, viewing without the field stop causes their brain to become distracted enough that they are unable to really settle down and enjoy the view.


Hopefully they aren't out there driving a car while distracted, they can't see the field stop in their eye, either.

#24 mayidunk

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Posted 11 May 2013 - 01:27 PM

I recall reading someplace that it has to do with how a person's brain perceives what it sees. Some people need to have the fixed frame of reference that a visible field stop provides, while others don't. IIRC, for people who need to see the field stop, it isn't so much a preference as it is a need! For them, viewing without the field stop causes their brain to become distracted enough that they are unable to really settle down and enjoy the view.


Hopefully they aren't out there driving a car while distracted, they can't see the field stop in their eye, either.

It's likely to be a learned behavior that only kicks in within the context of viewing through a scope. In other words, having viewed through the confines of the field stop for so many years (decades), many just can't get used to it not being there!

#25 Tom and Beth

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Posted 12 May 2013 - 01:35 AM

I recall reading someplace that it has to do with how a person's brain perceives what it sees. Some people need to have the fixed frame of reference that a visible field stop provides, while others don't. IIRC, for people who need to see the field stop, it isn't so much a preference as it is a need! For them, viewing without the field stop causes their brain to become distracted enough that they are unable to really settle down and enjoy the view.


Hopefully they aren't out there driving a car while distracted, they can't see the field stop in their eye, either.


Imagine driving down the road and being obsessed with seeing the frame of your windshield? :p






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