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Olivier Biot
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A review of the 31 Nagler vs. the 32 Edmund Erfle
      #3968819 - 08/07/10 06:01 AM

A review of the 31 Nagler versus the 32 Edmund Erfle

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Ocram
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Olivier Biot]
      #3968855 - 08/07/10 06:47 AM

I read this during:
My opinion:
What I expect what will happen to the reviewer:
What I am doing now:

No serious, this confirms what I have seen more than once as well. You don't need to spend a fortune when picking EP's for your specific scope.
Naglers however are do-it-allways-very-well-in-every-scope EP's.
That's the price you pay for a certain convenience. Got an SCT with a full set or erfles and buy a very fast Dob, get thee some Naglers/Pentax/Ethos to keep your views sharp. Then a Dob becomes a more expensive proposition. When you stick to quality ultra-wide EP's that's not an issue. Nor is it when you only look on-axis...then you can keep your Erfles.

End rant, nice review, albeit a bit short

Edited by Ocram (08/07/10 06:48 AM)


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Alex Gastélum
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Ocram]
      #3969196 - 08/07/10 12:10 PM

I wish the review had a slower telescope on the comparison,
the reviews of this eyepiece in excelsis ratings are not bad.
Will the eyepiece suffer from more distortion on a faster scope?


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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Alex Gastélum]
      #3969279 - 08/07/10 12:57 PM

I did make this review a bit short, but to answer your question this Erfle performs very well in Newt reflectors down to f4.5 and I have used it in an 94mm f7 Brandon refractor where it is very good across the whole field.

The truth is that it does even better in these latter 2 scope types than in an f10 SCT. That is because of the field curvature inherent in the SCT design.

I did compare this 32mm Erfle to a 32mm Televue Wide field in the 94mm f7 Brandon refractor and I thought the Edmund smoked it in every category. Contrast and sharpness and field of view.

Mark


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Alex Gastélum
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Mark Swanson]
      #3969324 - 08/07/10 01:21 PM

I have a refractor f6 and a dobsonian f4.5, do you recoment it for those?

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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Alex Gastélum]
      #3969471 - 08/07/10 02:54 PM

I just submitted an update to my review that will answer your question. I am sure it will be posted soon. I have used this eyepiece in an f7 94mm Brandon refractor with great results. I would guess it would do OK in an f6, but maybe not quite as well at the edge.

Mark


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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Alex Gastélum]
      #3969474 - 08/07/10 02:56 PM

I also used it in an 17.5" f4.5 reflector and it performed very well.You will here why in my update to my review.

Mark


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Olivier Biot
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Mark Swanson]
      #3969549 - 08/07/10 03:26 PM

Quote:

I just submitted an update to my review that will answer your question. I am sure it will be posted soon. I have used this eyepiece in an f7 94mm Brandon refractor with great results. I would guess it would do OK in an f6, but maybe not quite as well at the edge.

Mark




The Aug 7 update has been added to the initial review.


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eric_zeiner
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Olivier Biot]
      #3969876 - 08/07/10 06:58 PM

The only one thing that I noticed is that the Edmund web site say that the AFOV is only 68 degrees as opposed to the 82 degrees listed in this review.

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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: eric_zeiner]
      #3969927 - 08/07/10 07:36 PM

Yes, it does say that it is 68 degrees on the website. This was based on a prototype of this eyepiece and not the final product.The Edmund has a slighty larger true field than the Nagler 31.Look at the field stops I have listed under the specifications. Even Edmund says the eyepiece has a 42.5mm field stop. The 31 Nagler field stop is 42mm in diameter. To get the true field at the eyepiece you multiply the field stop diameter by 57.3 and then divide that by the focal length of the telescope in mm. A C8 with the Edmund would have a true field of 42.5 X 57.3 divided by 2032 = 72 arc minutes, or 1 degree and 12 minutes.

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eric_zeiner
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3969968 - 08/07/10 07:57 PM

Quote:

Yes, it does say that it is 68 degrees on the website. This was based on a prototype of this eyepiece and not the final product.The Edmund has a slighty larger true field than the Nagler 31.Look at the field stops I have listed under the specifications. Even Edmund says the eyepiece has a 42.5mm field stop. The 31 Nagler field stop is 42mm in diameter. To get the true field at the eyepiece you multiply the field stop diameter by 57.3 and then divide that by the focal length of the telescope in mm. A C8 with the Edmund would have a true field of 42.5 X 57.3 divided by 2032 = 72 arc minutes, or 1 degree and 12 minutes.




Thanks for the clarification and like a bonehead I did not even think to look at the field stops. How do you think these would perform in an f/5 or an f/6 refractor?


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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: eric_zeiner]
      #3970169 - 08/07/10 10:54 PM

If it were a TV Genesis with the field flattener in it I would guess it would do OK. You know the 4 element refractor. I know it did well in an f7 refractor, but it may not be quite as good on edge with an f5 or 6 refractor.

Mark


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Alex Gastélum
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3970307 - 08/08/10 01:16 AM

I was thinking on my triplet 80mm SV apo f6

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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Alex Gastélum]
      #3970640 - 08/08/10 10:48 AM

My Brandon 94mm f7 was a Rolend Cristen cemented triplet lens. The Edmund did well in that one. You can pick these used Edmund's up on the internet for under $100. They sell new at Edmund for $225.

Mark


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Starman1
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3971167 - 08/08/10 03:51 PM

Notes:
1) Spot diagrams for the Erfle design (the standard 5-element design, not the modified 6 element design) show:
f/10 on axis, 7 degrees off axis, 10 degrees off axis spots are smaller than the Airy disk.
f/5 even on axis, the spot is larger than the Airy disk.
Critical F/ratio = 8, meaning the eyepiece is not designed to handle f/ratios below f/8 without oblique rays causing astigmatism at the edge of the field.
The design has chromatic aberration on-axis. Red rays are not as focused as other colors. Fortunately, our night vision is insensitive to this color.
2) Spot diagrams for the Nagler design show:
--star images smaller than the Airy disk out well beyond 20 degrees off axis (this assumes the T5 design, on axis, is similar to the original type--Al Nagler told me it's actually smaller than this)
Critical f/ratio = 4

One can't deny what you experienced, but if the star images you saw were smaller in one eyepiece than the other, it may mean one eyepiece was not manufactured to design tolerances.
With such a low power, I wouldn't want to blame seeing conditions or mirror cooling, so the issue of spot size is difficult to address when both eyepieces should have displayed star images no larger than the Airy disk in your scope (which probably isn't visible at low power).

I've been observing a long time, and also have seen similar differences between eyepieces (spot size was one of the reasons I preferred Plossls to Abbe Orthoscopics, for example, and why I loved the Konig designs), even between different samples of the same eyepiece (!). Some of the eyepieces I've owned (and I've had a 31 Nagler for many years) had a noticeable variation from night to night--seeing conditions even affected the quality of my lowest power images. The edge of the field in the 31 Nagler seems to vary in quality for that reason, as well as my ability to accommodate a slightly curved focal plane, the tiredness of my eyes, the ability to achieve a sharp focus (somewhat difficult on short f/ratios), etc.

But I suspect the difference you saw may have been "sample-derived" rather than "design-derived", because the 31 Nagler I own is one of the sharpest eyepieces I've ever looked through, on-axis.


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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Starman1]
      #3971410 - 08/08/10 06:30 PM

Don, I understand what you are saying about the spot size for the 5 element version, but this is a computer designed David Rank eyepiece and it has 6 elements.

On the Weatherman web site there is a review of the 31 Nagler versus the 30mm Leitz by Bob Luffel. I hope I spelled that right. He did a comparison of these two eyepieces and he gave the Nagler 31 the edge on the edges, but said that the Leitz was in his estimation about 20 to 25% sharper than the 31 Nagler in the central area. He ultimately chose the Leitz to keep for reasons that pertained to his own set of eyes. Not for any other reasons I just stated before this last reason. There was something about his own eyes that made the 30mm Leitz easier to view thru.

I have owned several different Edmund 32 Erfles over the years. I would sell and then buy one back. You know how it is in this hobby. The one I have now will never be sold. These are all the same eyepieces I am talking about.

I have a long history of watching this eyepiece destroy one eyepiece after another in the centerfield position.I read a thread on the internet that compared a 5 element 31mm Proxima Erfle to the 6 element 32mm Edmund Erfle and the reviewer said that the Edmund was sharper in the central area and that it would be a great eyepiece for looking at open clusters.

The 31 Nagler was very sharp in the center. I am saying that the Edmund was superhuman sharp in the central area.Tinier pinpricks.

I have a 20 year history of sticking one eyepiece after another in my Diagonal and watching it go down in flames against the 32mm Edmund Erfle in the centerfield area.

Mark

Edited by Mark Swanson (08/08/10 06:52 PM)


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Starman1
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3971515 - 08/08/10 07:31 PM

You would love the standard Konig designs.
Don


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Jon Isaacs
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Starman1]
      #3971553 - 08/08/10 07:49 PM

A few quick thoughts:

- I don't think anyone is seeing the Airy Disk with a 3.1mm exit pupil...

- Also, the rear port/rear baffle on an 8 inch F/10 SCT is 38mm (1.5 inches). The has to be some vignetting with a 42mm field stop.

Jon


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Daniel Mounsey
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Jon Isaacs]
      #3973849 - 08/09/10 10:57 PM

Quote:

A few quick thoughts:

- I don't think anyone is seeing the Airy Disk with a 3.1mm exit pupil...


Jon



Agreed


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Starman1
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Daniel Mounsey]
      #3974040 - 08/10/10 02:05 AM

Still, if the star points are smaller with one eyepiece, either one eyepiece has spots larger than the Airy disk on axis, or the eyepiece with larger stars has substantial spherical aberration, or the observer didn't achieve as tight a focus with one eyepiece as with the other.
You don't see the Airy disk as a disk at low powers, but you can definitely see bloated star images in comparison.
It's the why of it that interests me, because both eyepieces should display star images of equal size.


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Mark Swanson
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Starman1]
      #3974601 - 08/10/10 11:45 AM

Don,

I just submitted info from Edmund to cloudynights that gives stats on spot size, distortion, and false color for this 32 Edmund Erfle. Maybe you can compare it to the 31 Nagler info you have.

Mark


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Larry Geary
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Starman1]
      #3974686 - 08/10/10 12:25 PM

Perhaps the transmission losses in the Erfle are greater, resulting in dimmer stars which appear smaller.

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Jon Isaacs
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Larry Geary]
      #3974719 - 08/10/10 12:40 PM

Another thoughts:

For me, the performance of a widefield eyepiece like the 31mm Nagler is of most importance in a fast scope simply because fast scopes provide the widest fields of view for a given aperture.

So of particular interest is the statement that the Edmunds Erfle eyepiece performs well in an F/4.5 Newtonian. I am curious as to the aperture of the Newtonian used for this test as well as what sort of coma corrector was used.

Jon Isaacs

Jon Isaacs


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Starman1
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Larry Geary]
      #3974744 - 08/10/10 12:51 PM

Quote:

Perhaps the transmission losses in the Erfle are greater, resulting in dimmer stars which appear smaller.



Interesting idea. It could be tested by looking for the faintest stars in the field and comparing those.


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Mark Swanson
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Larry Geary]
      #3975454 - 08/10/10 07:08 PM

I don't think so. This eyepiece uses the finest anti-reflection coatings and has fantastic contrast.I would venture to say it may have more transmission than the 31 Nagler.
I think what is going on here is that it is difficult for some people to believe that there could be an eyepiece that is sharper than a Nagler at any position in the field. It should occur to people that to get that sharp of an edge in a nagler, that there might by necessity be a very tiny loss of sharpness at centerfield.The Nagler is very sharp. Just not quite as sharp in the center of the field as the 32 Edmund.

Mark


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Mark Swanson
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Jon Isaacs]
      #3975476 - 08/10/10 07:19 PM

It was in a 17.5" f4.5 Coulter Dob. I did not have a coma corrector in it at all. I had put on a 2" tectron focuser.

I compared it to a 32mm Televue wide field. It was not one of the smoothside wide fields from Japan, but a later version with rubber eyecups. I can confirm that the later versions were not as good as the smooth side. I have looked through both.I had a smooth side, but sold it to buy the edmund 32 erfle. At a star party I compared someone else's 32 televue to my Edmund 32. It was the rubber eyecup version and the Edmund outperformed it on contrast and sharpness.This Edmund works very well in reflectors and I was pleased with the incredible wide field with the edmund in that dob. I thought the whole field was useable.

Mark


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Jon Isaacs
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Mark Swanson]
      #3975550 - 08/10/10 08:01 PM

Quote:

It was in a 17.5" f4.5 Coulter Dob. I did not have a coma corrector in it at all.




Here is a calculation: The coma free field of an F/4.5 is about 1.6mm. In a 17.5 inch this corresponds to a field of view of 2.75 arcminutes. A 31mm eyepiece would provide about 64x and so the diffraction limited, coma free apparent field of view would be a 3 degree, a pretty small portion of a 82 degree AFoV.

I honestly don't see how anyone can draw conclusions about on-axis sharpnes sharpness in an F/4.5 Newtonian without using a coma corrector, particularly in a Dobsonian when the diffraction limited field is only 3 degrees.

YMMV

Jon Isaacs


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Starman1
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Mark Swanson]
      #3975577 - 08/10/10 08:15 PM

If you thought the whole field of view of a low power Erfle was "usable" at f/4.5 without a coma corrector, then you must have really lax standards about star image quality at or near the edge of the field.
Because the spot diagram of an Erfle at f/5 shows the star images to exhibit severe chromatic aberration:
http://www.telescope-optics.net/eyepiece_aberration_2.htm
and even worse coma from the scope:
http://www.rfroyce.com/mirror_performance.htm
not to mention field curvature from the scope:
http://starizona.com/acb/basics/equip_optics101_curvature.aspx
The last time I tried the 31 Nagler at f/5, without coma correction, the star images at the edge of the field were easily 10X as large as the star images in the center.
Now you have me interested in seeing how good the Erfle is WITH coma correction.


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Mark Swanson
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Re: A review of the 31 T5 vs. the 32 Edmund Erfle new [Re: Starman1]
      #3975704 - 08/10/10 09:20 PM

I had this dob in the early nineties and at one time I did own a 2" Paracor. I may be mistaken on saying that i did not use a coma corrector. I did use this scope without a coma corrector for a while and added the coma corrector later. I could have had it in place when I used the Edmund 32 in that dob. I do remember it being a good view, so I probably did have the Paracor in the scope.

Mark

Mark


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John Rhodes
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Olivier Biot]
      #3977226 - 08/11/10 03:57 PM

Oliver, Group,
Noting the review and 8/7/10 update that states that the 31mm Nagler isn't sharp on axis in comparison, we must question the report since in his f/10 SCT, the 31mm Nagler has a Strehl ratio on-axis of over 99.9% and no visible color.  Anecdotally we've had no returns or comments at Tele Vue about lack of axial sharpness.  The comment the author makes in this thread regarding the possibility of having to give up axial sharpness for edge field sharpness is one of those hackneyed old tales that needs to be laid to rest.  Kind of like the notion that Barlows degrade the image, you can't make a good zoom eyepiece, and fast refractors can't have good color correction, it ain't so.


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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: John Rhodes]
      #3978120 - 08/12/10 12:24 AM

John,
I never said the Televue 31 Nagler was not sharp on axis in comparison. They are both very sharp on axis. I am certain that the Edmund was slightly sharper. If you don't believe me go out and buy an Edmund 32 Erfle and take the plunge. Compare both eyepieces and then honestly tell me the 31 Nagler is sharper on axis.

Don't rely on Televue's reputation only. Go do the test yourself. I did.

Go to the weatherman web site and read the review by Bob Luffel comparing the 30mm Leitz 88 degree eyepiece in which he said that the 30mm Leitz was in his estimation about 20 to 25% sharper on axis than the 31mm Nagler. He gave the edges to the 31 Nagler.

I am not the only one with eagle eyes.

Mark


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NorthWolf
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3978161 - 08/12/10 01:06 AM

Pentax XW 30mm FTW! 1.63 lbs of Crystal.

88 degrees is awesome though.


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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: John Rhodes]
      #3978227 - 08/12/10 02:05 AM

John,

I noticed that you listed every refractor Televue makes and all eyepieces they make as the equipment you use. Therein lies your problem. Instead of relying on Strehil figures, I can't even spell it, go look thru other equipment.The truth is your company has fine products, but nothing that can't be bested by another company. Example: Celestron Ultimas out perform Televue Plossls. I have very little use for pincushion distortion which every Televue eyepiece has.The original Meade series 4000 Ultrawides outperform the type 1 Naglers both during daytime and nightime with their flat fields. The 14mm Meade Ultrawide is a better eyepiece than the 13mm type 1 Nagler.Much easier to view thru and flatter field while still sharp at the edge. I am only referring to these older designs because these are what I have looked thru and compared. I had a 94mm f7 Brandon refractor with a cemented Cristen triplet apo lens that was sharper over most of the field than the original TV Genesis with the 4 element system. It had a flourite element in it.
Amateur Astronomy has been around long before you and I were even born and would be thriving today whether your company ever came along or not.I am frankly tired of all the suckups that rave about your company and it is time for someone to show another viewpoint.

Mark Swanson


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Alex Gastélum
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3978767 - 08/12/10 12:22 PM



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Jon Isaacs
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3978863 - 08/12/10 01:20 PM

Quote:

Example: Celestron Ultimas out perform Televue Plossls.




In 1996 Sky and Telescope did an exhaustive comparison of various Plossls. (Page 41 April 1996 if I recall.) These included various tests on the optical bench as well as field comparisons involving several experienced observers.

The result, they rated the Ultimas and TV Plossls at that top and of equal quality. Meade was probably their biggest advertiser at the time but the Meade series 4000 SuperPlossls, 4 elements by that time, were pretty much in the middle.

When I judge an eyepiece in a particular scope, I pick specific targets and if I want to write about what I see, then I refer to what I saw on those particular targets. For on-axis comparisons of a widefield eyepiece in a fast scope, I typically use the wild duck cluster. It is small and filled with a great number of tiny "pinpricks."

Jon Isaacs


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Tamiji Homma
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Daniel Mounsey]
      #3978871 - 08/12/10 01:24 PM

Quote:

Quote:

A few quick thoughts:

- I don't think anyone is seeing the Airy Disk with a 3.1mm exit pupil...


Jon



Agreed




Hi Daniel,

Can you bring your Nagler 31 and Leitz 30 to NUTS star party this weekend? I'll bring my Edmund 32 Erfle, XW 30, something near 30 that I have

Tammy


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Daniel Mounsey
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Tamiji Homma]
      #3978914 - 08/12/10 01:46 PM

No problem, I'll bring both.

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Tom TAdministrator

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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #3978943 - 08/12/10 02:00 PM

Quote:

Example: Celestron Ultimas out perform Televue Plossls.




FWIW This is such a broad statement, it's somewhat meaningless. I've had both lines, and Celestron Ultimas and TV Plossls are both fine performers (for my own use I kept the TV plossls and sold the Ultimas).

Quote:


I am frankly tired of all the suckups that rave about your company and it is time for someone to show another viewpoint.

Mark Swanson




As long as there are different types of gear there will be folks who for whatever reason favor one over the other. Just because you like one and someone else likes another does not make either of you wrong in your choice. Everyone is certainly entitled to their own viewpoint but on this board lets keep in mind the need to be tolerant of one another please. Thank you - (That's me speaking as board admin here...)

Speaking as an amateur astronomer, I'd venture to say that you should be aware that John is a company rep and has access to design information. When he states that the strehl ratio of the eyepiece on axis is 99.9%, that means that by design the eyepiece places 99.9% of the light within the airy disk. Since you can't resolve beyond the airy disk (in this case), that's about as good as you can get. Now - I'm not saying you didn't see what you say you saw - I'm just suggesting that the technical details of what's actually going on might be different - ie, transmission (as has already been suggested), contrast, light cone behavior, or something else that might involve user perception. (For example - I can see where certain types of astigmatism might lead one to believe that on axis star images were smaller.) Like was pointed out - I don't think you're really seeing the airy disk in these eyepieces (the magnification is way too low), but then again

Anyway - it's something to think about.

Tom T.


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Jon Isaacs
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Tom T]
      #3978991 - 08/12/10 02:27 PM

Quote:


FWIW This is such a broad statement, it's somewhat meaningless. I've had both lines, and Celestron Ultimas and TV Plossls are both fine performers (for my own use I kept the TV plossls and sold the Ultimas).




The measurements and observations of the Sky and Telescope report were much more detailed as was the summary. I was merely responding to Mark's blanket claim that the "Celestron Ultima's out perform the TeleView Plossls." Sky and Telescope singled these two series and being a cut above others tested.

Jon Isaacs

Edited by Jon Isaacs (08/12/10 02:28 PM)


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Tom TAdministrator

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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Jon Isaacs]
      #3978997 - 08/12/10 02:31 PM

Jon,

I remember that article and am in agreement with you. FWIW My comment was directed towards Marks statements - not yours.

Sorry for any confusion.

T


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Jon Isaacs
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Tom T]
      #3979077 - 08/12/10 03:16 PM

Quote:

Jon,

I remember that article and am in agreement with you. FWIW My comment was directed towards Marks statements - not yours.

Sorry for any confusion.

T




Tom:

Now that I read your post more closely, it is not confusing at all, I see the mistake was mine and caused by reading what you had written too quickly.

I bought several of the standard Taiwanese Celestron Plossls after reading that review, I still have the 32mm plus a second identical 32mm, they severed me well.

Jon


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KWB
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Jon Isaacs]
      #3979194 - 08/12/10 04:20 PM

"Go to the weatherman web site and read the review by Bob Luffel comparing the 30mm Leitz 88 degree eyepiece in which he said that the 30mm Leitz was in his estimation about 20 to 25% sharper on axis than the 31mm Nagler. He gave the edges to the 31 Nagler.

I am not the only one with eagle eyes."
-----------------------

To be totally fair,this thread isn't about the Leitz eyepiece nor anothers review of that eyepiece or any other eyepieces that aren't germane to your review. This thread is about your review of Nagler and the Edmund and IMO only about those 2 eyepieces. I'd rather only hear about these 2 eyepieces being discussed and compared.


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Alex Gastélum
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Tamiji Homma]
      #3979247 - 08/12/10 04:43 PM







Hi Daniel,

Can you bring your Nagler 31 and Leitz 30 to NUTS star party this weekend? I'll bring my Edmund 32 Erfle, XW 30, something near 30 that I have

Tammy




I will appreciate your opinions on that comparison very much.
The best and more objective eyepiece reviews that I have read were written by Danien Mounsey.


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Mark Swanson
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Tom T]
      #3979329 - 08/12/10 05:35 PM

I should not haven taken that tone with John and will be more careful in the future.
With regard to the Ultima versus TV Plossl, I will be more specific. It is my opinion that the 5 element Ultima,Ultrascopic,original meade smooth side 5 element plossls,are better performers than the 4 element Plossls such as the Sirius by Orion, 4 element Meade,4 element Televue, 4 element anything. In this case I was not so much having a problem with the Televue, as I think that the 5 element ones, which are a highly corrected Erfle really are better.There must be something to this because you almost can't give away these 4 element versions on A-mart, cloudynights, etc.Post a 5 element version and you have immediate interest. I have a 35mm Rini 5 element that is like these other 5 element versions and it performs better than my 32mm Meade 4 element plossl. Better contrast and sharpness across the field. It is better on edge than the meade also.

Mark


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spaceydee
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Mark Swanson]
      #4016591 - 08/30/10 11:18 PM

Folks, I've unlocked this thread and have removed a number of posts. Please keep posts civil, polite, and respectful. From the TOS:

* Play Nice
* Share
* Be Polite
* Be Honest
* Respect other members & the administrators and moderators who are working to keep this board a useful resource.

Posts that are not respectful of other individuals (be they members or not) are not welcome here.


Please follow the TOS or this thread may become locked again and/or posts deleted.

thanks!


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Jim Romanski
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Olivier Biot]
      #4018953 - 09/01/10 12:05 AM

I read this review a while ago. I have to wonder if perhaps what was being observed was the effects of field curvature. If that's the case it would be useful to compare the two eyepieces in a scope known to have a very flat field such as a petzval refractor. Otherwise it's hard to say how much field curvature is from the scope versus the eyepiece. Sometimes certain eyepiece and scope combos cancel out the field curvature while others add up to more curvature. SCT are known to have curved fields.

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Alex Gastélum
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Loc: Tijuana, México
Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Daniel Mounsey]
      #4019672 - 09/01/10 12:08 PM

Quote:

Hi Daniel,

Can you bring your Nagler 31 and Leitz 30 to NUTS star party this weekend? I'll bring my Edmund 32 Erfle, XW 30, something near 30 that I have

Tammy.




Quote:

No problem, I'll bring both.




Hi Daniel:
Did you made the comparison, I am interested on your opinion.

Best regards.


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Daniel Mounsey
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Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Alex Gastélum]
      #4021058 - 09/01/10 10:46 PM

Hi ALex,
Unfortunately I am not allowed to comment, but Tammy might be able to share his thoughts.


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Alex Gastélum
super member


Reged: 06/04/08

Loc: Tijuana, México
Re: A review of the 31 Nagler vs. the 32 Edmund Er new [Re: Tamiji Homma]
      #4021479 - 09/02/10 06:30 AM






Hi Daniel,

Can you bring your Nagler 31 and Leitz 30 to NUTS star party this weekend? I'll bring my Edmund 32 Erfle, XW 30, something near 30 that I have

Tammy






Hi ALex,
Unfortunately I am not allowed to comment, but Tammy might be able to share his thoughts.




Hi Tammy:
Can you comment about that comparison?


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Frank Marino
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Olivier Biot]
      #4734510 - 08/07/11 12:30 AM

Hi all,
The FOV indicated for the 32 Edmond Erfle is 82 degrees. Isn't it 60?
Also it's described as a 6 element eyepiece. isn't it a 5-element?
Any takes on this?


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PJ Anway
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Re: A review of the 31 Nagler vs. the 32 Edmund Erfle new [Re: Frank Marino]
      #4969180 - 12/16/11 08:32 AM

Quote:

Hi all,
The FOV indicated for the 32 Edmond Erfle is 82 degrees. Isn't it 60?
Also it's described as a 6 element eyepiece. isn't it a 5-element?
Any takes on this?




By measuring the true field and calculating the apparent field, I got 72°. Closer to the stated 68° AFOV listed on Edmund's site. Also, according to the diagram on Edmund's site there are six elements in three groups. Here's the link:

http://www.edmundoptics.com/products/displayproduct.cfm?productid=2074

By the way, I really like this eyepiece in my 4" f/10 refractor! f/10 is so very forgiving when it comes to aberrations.


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