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Equipment Discussions >> Eyepieces

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Astrojensen
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5678729 - 02/14/13 02:44 AM

Quote:

Field Curvature all depends on how long / short your focal length is.




Both telescopes AND eyepieces can have field curvature. Or they can have flat fields. It depends on the design. It is therefore wrong to say that field curvature all depends on the focal length [of the telescope].

Quote:

What a crock of doo-doo that quote is!




It was actually quite correct.


Clear skies!
Thomas, Denmark


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RogueGazer
super member


Reged: 06/10/12

Loc: Central Point Oregon
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5678783 - 02/14/13 05:22 AM

Quote:

"I have spoken with with our field specialist and our owner about this before and this occurs with these types of eye pieces when viewing bright objects. It is not a defect in the eyepieces it is an aberration that occurs in combination with how the light goes through the eyepiece and how your eye receives the light. It is my understanding that it lessens when viewed from and certain distance away from the eyepiece or when viewed at a light angle."




What a crock of doo-doo that quote is!

Cheers,




If I have to pull my eye back further to correct the problem there goes my 82* AFOV. I might as well use a plossl not that what he said matters beause nothing I have tried fixes the problem unless I get so far back from the EP I see nothing at all. I have read a lot of great reviews on this eyepiece and how great the moon looks. Even my 11 year old son thought it looked like trash. I suspect I may have gotten a bit of a dud but fighting it is probably a losing battle. I just wont use it for lunar observations. It still is a great lower light EP.


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: ES 82* 18 or Meade 5K 20? new [Re: RogueGazer]
      #5678795 - 02/14/13 05:40 AM

Quote:

Both telescopes AND eyepieces can have field curvature. Or they can have flat fields. It depends on the design. It is therefore wrong to say that field curvature all depends on the focal length [of the telescope].




Yes, however, You can take a 14mm Pentax XW, put it in my 10" F/4.7 and the field curvature is very strong. Now, take the same eyepiece and put it in an F/10 CAT telescope and the field curvature is no longer there.

Did this many times with many different eyepieces!

Cheers,


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5678796 - 02/14/13 05:42 AM

Quote:

If I have to pull my eye back further to correct the problem there goes my 82* AFOV. I might as well use a plossl not that what he said matters beause nothing I have tried fixes the problem unless I get so far back from the EP I see nothing at all. I have read a lot of great reviews on this eyepiece and how great the moon looks. Even my 11 year old son thought it looked like trash. I suspect I may have gotten a bit of a dud but fighting it is probably a losing battle. I just wont use it for lunar observations. It still is a great lower light EP.




The ES 82's and some of the Meade Series 5000 UWA eyepieces have poor baffling and a poor design on the bottom of the eyepiece. There is a thread here somewhere showing a felt ring added to the bottom of the eyepiece to correct bad flaring and internal reflections. Bright targets like Jupiter and the moon show really bad internal reflections, so the quote from this "certain person" from ES is handing you, or someone else a big load of BULL to try and save face.

Cheers,


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RogueGazer
super member


Reged: 06/10/12

Loc: Central Point Oregon
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5678829 - 02/14/13 06:26 AM

Quote:


The ES 82's and some of the Meade Series 5000 UWA eyepieces have poor baffling and a poor design on the bottom of the eyepiece. There is a thread here somewhere showing a felt ring added to the bottom of the eyepiece to correct bad flaring and internal reflections. Bright targets like Jupiter and the moon show really bad internal reflections, so the quote from this "certain person" from ES is handing you, or someone else a big load of BULL to try and save face.

Cheers,




I read about that as well.I will rig something up similar to their rig job and see how it works. I have low expectations so I wont get too disappointed when it fails. Always borrow money from a pessimist. He won't expect it back


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csrlice12
Postmaster
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Reged: 05/22/12

Loc: Denver, CO
Re: ES 82* 18 or Meade 5K 20? new [Re: RogueGazer]
      #5679067 - 02/14/13 09:56 AM Attachment (6 downloads)

"I have spoken with with our field specialist "

Our Field Specialist:


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russell23
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Reged: 05/31/09

Loc: Upstate NY
Re: ES 82* 18 or Meade 5K 20? new [Re: mitaccio]
      #5679208 - 02/14/13 11:12 AM

Quote:

I am looking for an eyepiece 20-18mm to fill the gap I have. Currently have a 24mm Meade 5K and a ES 82* 14mm & 8.8mm Both the ES 82* 18mm and the Meade 5K 20mm are $149, waterproof, and would match my existing eyepieces. Here's the numbers for my scope:

Meade 5K 20mm: 101X, 2.0 Exit Pupil at 17mm eye relief
ES 82* 18: 113X, 1.8 Exit Pupil at 13mm eye relief

Both eyepieces are very close in design from my understanding. But which one is the better performer? I am leaning towards the Meade, even though it is heavier as it offers a slightly bigger exit pupil.




The problem is that while the 20mm Meade WP UWA is listed on numerous websites nobody has yet to have any in stock - ever (not that I'm aware of). So nobody can say yet which is better.

Based upon my experience with ES, Meade, and Celestron eyepieces I would say that while all three companies may be using the same basic optical design for the 82's, I think that ES does the best job of the three companies in terms of overall quality of optical performance and that Celestron does the worst job - and this includes the other lines.

Specifically I find that the across the full field of an eyepiece the ES eyepieces seem to have the "cleanest" presentation. Both the 6.7mm ES82 and 28mm ES68 that I have provide a nice uniform sky background and minimal scattering, and/or "grainy" texture to the light. Next comes Meade based upon what I've seen from an 8.8mm Meade UWA and a 12mm Meade HD-60. Both eyepieces shows some edge brightening and while very good - did not present as clean a view as the ES eyepieces. Finally comes Celestron based upon a 19mm 82 deg Luminos and a 12mm X-cel LX. Both eyepieces showed edge brightening of a moderate level and a noticeable amount of "grainy" (as opposed to "Hi-def") texture to the light.

So in my opinion if other specs on the eyepieces are not an issue (eye relief differences ...)you can't go wrong with the ES option if this is a gap you need to fill.

Dave


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Astrojensen
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5679846 - 02/14/13 04:28 PM

Quote:

The ES 82's and some of the Meade Series 5000 UWA eyepieces have poor baffling and a poor design on the bottom of the eyepiece. There is a thread here somewhere showing a felt ring added to the bottom of the eyepiece to correct bad flaring and internal reflections. Bright targets like Jupiter and the moon show really bad internal reflections, so the quote from this "certain person" from ES is handing you, or someone else a big load of BULL to try and save face.




Sometimes I really wonder if we're talking about the same eyepieces... Our experiences differ so extremely, that it really makes me wonder if we maybe have two different versions.

In my 12" f/5 Lightbridge, the ES 30mm, 18mm, 11mm and 8.8mm all present an extremely clean view of the Moon with zero glare, no ghost images and no reflections anywhere in the field of view. The waxing crescent Moon with the illuminated portion just outside the field stop in the 18mm ES82 (an acid test for these aberrations in most telescopes) showed a superb view of the earthshine. There was absolutely NO glare, ghosts or reflections in the image. The same with Jupiter in the 12". The image is extremely clean. The color of Jupiter and the Moon is neutral, with no, however subtle, yellowing. My 9mm UO ortho shows a considerably yellower image than the 8.8mm ES82.

I will add that I have observed for over 20 years with orthos and high-end Zeiss and Meiji Techno research-grade microscope eyepieces and am EXTREMELY picky about internal reflections and ghosting, which I find completely off-putting and extremely annoying on the Moon, however sharp the eyepiece may otherwise be. The ES eyepieces I own are right up there with my research-grade 25mm Zeiss eyepieces in clarity and lack of ghosting and reflections. In other words, some of the finest I've seen. The 18mm is especially stunning. The first time I saw the Moon through it on the 12", my jaw dropped and I let out a loud gasp. It was really fantastically good. And I've observed the Moon quite a few times and under much better conditions than that evening. Still, it was a jaw-droppingly good view, and not just because of the wide field, but because the image quality was so exceptionally good.

There is a relatively easily seen orange-yellow ring around the field stop in the 30mm ES82, when observing the Moon or in daylight. Its presence depends on the eye position. I have to get my eye quite close to the lens, then it is at a minimum. In the 18mm ES82, it is much less than in the 30mm and not very noticeable. In the 11mm and 8.8mm, it is there only if I look for it, unless I look into the eyepiece at a really weird angle I would never use in practice. It is invisible on deep-sky.

I'll grab some photos of my ES 82s and upload them, so we can find out whether they are the same or not. It'll be worthwile to find out. Perhaps there are some early samples that are less good?


Clear skies!
Thomas, Denmark


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Astrojensen
Post Laureate
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5679859 - 02/14/13 04:38 PM

Quote:

Yes, however, You can take a 14mm Pentax XW, put it in my 10" F/4.7 and the field curvature is very strong. Now, take the same eyepiece and put it in an F/10 CAT telescope and the field curvature is no longer there.

Did this many times with many different eyepieces!




That really makes me wonder, since some catadioptric telescopes have extremely curved fields and others don't. Classic SCTs have very curved fields, even more so than refractors of the same focal length. A classic refractor will have a field curvature radius of about 1/3rd the focal length, while a classic SCT will have a field curvature radius of 1/10th the focal ratio!

If we compare a classic 10" f/4.7 newtonian and a classic 10" f/10 SCT, then the newtonian will have a field curvature radius of 1200mm, roughly, while the SCT will have one of 250mm! The SCT, in other words, have a field curvature almost five times worse than the newtonian of half the f/ratio!

My 8" f/10 SCT has a very curved field and eyepieces show strongly out of focus stars near the edge.


Clear skies!
Thomas, Denmark


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: ES 82* 18 or Meade 5K 20? new [Re: Astrojensen]
      #5680121 - 02/14/13 07:51 PM

What you say, and what I have seen with my eyes, as well as my observing buddies, shows different. You can throw all the theory at me you want, but the eye does not lie. It seems you have an answer for everything I say no matter what.

You're a walking, talking encyclopedia bro!

Cheers,


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stevew
Now I've done it


Reged: 03/03/06

Loc: British Columbia Canada
Re: ES 82* 18 or Meade 5K 20? new [Re: Astrojensen]
      #5680289 - 02/14/13 09:57 PM

Thomas I'd have to agree with you.
I am not much of a lunar observer, but I did test out my 18mm ES on the Moon with my Antares 105x1300mm and have not seen any flaring or bright rings at the edge of the field.
Jupiter shows none either.
If other observers are seeing these artifacts maybe there is some quality control issue going on with these eyepiece.

Steve


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: ES 82* 18 or Meade 5K 20? new [Re: stevew]
      #5680323 - 02/14/13 10:19 PM

Quote:

Thomas I'd have to agree with you.
I am not much of a lunar observer, but I did test out my 18mm ES on the Moon with my Antares 105x1300mm and have not seen any flaring or bright rings at the edge of the field.
Jupiter shows none either.
If other observers are seeing these artifacts maybe there is some quality control issue going on with these eyepiece.

Steve




The ES 18mm UWA is prob far superior to the 18mm Meade 5000 UWA I guess?

cheers,


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RogueGazer
super member


Reged: 06/10/12

Loc: Central Point Oregon
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5680334 - 02/14/13 10:29 PM

I'm going to post a picture of what I am seeing as soon as the Moon and weather cooperate.

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Astrojensen
Post Laureate
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5680627 - 02/15/13 03:15 AM

Quote:

What you say, and what I have seen with my eyes, as well as my observing buddies, shows different. You can throw all the theory at me you want, but the eye does not lie. It seems you have an answer for everything I say no matter what.




I am honestly trying to find an explanation as to why we are seeing so very different things in the ES82 eyepieces. It seems you are missing this point completely and try to oppose my effort. The eye does not lie, indeed, but that also includes mine. I honestly report what I am seeing and offer an honest explanation to why we see may differ. I am in no way trying to belittle any product, if that is the impression you have somehow got.

Quote:

You're a walking, talking encyclopedia bro!




I've been called that before and take it as a compliment.


Clear skies!
Thomas, Denmark


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Astrojensen
Post Laureate
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5680632 - 02/15/13 03:22 AM

Quote:

The ES 18mm UWA is prob far superior to the 18mm Meade 5000 UWA I guess?




That could very well be the case, if their designs differ. And there are many things that point in the direction that their designs actually are quite different and that there may even be a significant upgrade from the early ES82s to the latest production models. Sometimes manufacturers make significant changes in their product without much fanfare.

What makes all of this so frustrating is that no one individual seems to own all versions of these eyepieces at the same time and thus direct A/B comparisons are extremely hard to make. Some report bad ghosting and reflections, while other see not the slightest hint of any. This clearly indicate that something has been changed in the line.


Clear skies!
Thomas, Denmark


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rtomw77
Pooh-Bah
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Reged: 10/06/04

Loc: Deer Valley, AZ
Re: ES 82* 18 or Meade 5K 20? new [Re: Astrojensen]
      #5680661 - 02/15/13 04:06 AM

Something else you might consider is size and weight. The ES 18mm has a weight of 14 oz, and the widest part of the body of the EP is about 2.2". It fits in a 65mm bolt case.

The listed weight of the Meade 20mm is 26 oz, and it has a bigger body. It probably requires a 80-90mm in diameter bolt case.

I have the ES 82º 18mm, and I am very happy with it.

Tom


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russell23
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Reged: 05/31/09

Loc: Upstate NY
Re: ES 82* 18 or Meade 5K 20? new [Re: Scanning4Comets]
      #5681077 - 02/15/13 10:21 AM

Quote:

Quote:

Thomas I'd have to agree with you.
I am not much of a lunar observer, but I did test out my 18mm ES on the Moon with my Antares 105x1300mm and have not seen any flaring or bright rings at the edge of the field.
Jupiter shows none either.
If other observers are seeing these artifacts maybe there is some quality control issue going on with these eyepiece.

Steve




The ES 18mm UWA is prob far superior to the 18mm Meade 5000 UWA I guess?

cheers,




Well - like I said in my earlier post - in my experience using current offerings from ES, Meade, and Celestron, I feel that Explore Scientific has he best execution of the eyepiece. I don't know how much of that is optical design adjustments, how much of that is internal blackening requirements, how much of that is variations in coatings, how much of that is requested lense polish specs ... and so on. I just know that I rank the three companies as such:

1st: ES, 2nd: Meade, 3rd: Celestron. I would also say that the gap between Meade and Celestron is larger than the gap between ES and Meade.

Dave


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russell23
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Reged: 05/31/09

Loc: Upstate NY
Re: ES 82* 18 or Meade 5K 20? new [Re: rtomw77]
      #5681082 - 02/15/13 10:26 AM

Quote:

Something else you might consider is size and weight. The ES 18mm has a weight of 14 oz, and the widest part of the body of the EP is about 2.2". It fits in a 65mm bolt case.

The listed weight of the Meade 20mm is 26 oz, and it has a bigger body. It probably requires a 80-90mm in diameter bolt case.

I have the ES 82º 18mm, and I am very happy with it.

Tom




I just wish ES didn't inset their eyelenses so much on some of the ES82 line. The 19mm Celestron Luminos had ~20mm of eye relief and the 18mm ES only has 13mm? I have to believe the designs are similar enough that they could bring those eyelenses closer to the surface to squeak out a few more mm of eye relief. That is really the only problem I've seen with any of the ES eyepieces - and it is only a problem for those of us that have astigmatism and need to wear glasses while observing. It is not a problem with my 6.7mm ES82 because the exit pupil is small enough I don't need my eyeglasses, but the 18mm would be a problem and I really would like to get one.

Dave


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csrlice12
Postmaster
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Reged: 05/22/12

Loc: Denver, CO
Re: ES 82* 18 or Meade 5K 20? new [Re: russell23]
      #5681600 - 02/15/13 02:06 PM

It may only have 13mm of eye relief, but what an amazing 13mm it is.........sorry for all the eyeglass wearers....

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russell23
Post Laureate
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Reged: 05/31/09

Loc: Upstate NY
Re: ES 82* 18 or Meade 5K 20? new [Re: csrlice12]
      #5681642 - 02/15/13 02:22 PM

Quote:

It may only have 13mm of eye relief, but what an amazing 13mm it is.........sorry for all the eyeglass wearers....




Actually, looking more closely at the picture of the 18mm ES82 on Astronomics it doesn't look like the eyelense is recessed that much. Is it possible to see the full field with glasses on?

Dave


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