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Hapii

Eye relief VS fov. FIght !

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Hi there,

For exemple :
If you have to choose between 82° eyepiece with 13mm eye relief VS a 68° EP with 20mm eye relief (assuming they have same build quality, and price)

What would you prioritise for your viewings ?
At what point would you consider a poor eye relief ? below 15mm ? Lower ?
Does a poor eye relief is even worse when the Fov is big?

PS: People who are wering glasses doesn't count :D.

Cheers.

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Personally, I think 10-15mm eye relief is about right. I cannot stand hovering over an eyepiece which is sometimes necessary with longer eye relief.

Given your choices I'd go for the 82 degree with 13mm but my own preference is for eyepieces with 70 degrees or less and I have found that some 70+ degree apparent field eyepieces I have tried (even premium ones like Ethos and newer Naglers and to some extent Delos) show off axis chromatic aberration. My mono eyepieces are now mainly Panoptic and Delites for this reason.

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Ok interesting, 

Actually it's because i don't know if i should take the 11mm ES 82° or the Baader Hyperion 10mm 68° :s 

 

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82°. 13mm or 14mm eye relief are enough, and the Hyperion line is not as sharp as the Explore 82° line, more field doesn't necessarily cause more edge aberration. I own the 10mm Hyperion, some greenish fringing happens around everything bright. Center sharpness is okay but the Hyperion line is not competitive anymore, 120€ for a 68° when many very good 82°'sell for 95€ is not a bargain. I paid only 90€ for my Hyperion in 2013 but now I'd go for an Explore or its Opticstar clone.

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_322

Add 11% to the price in £ to convert it to €.

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I have the 14mm and 30mm ES 82's with eye relief of 15mm and 21mm, respectively. I also have the Tele Vue Delos 10mm with eye relief of 20mm. I find the Delos provides a much more comfortable field of view at 72deg, probably much the same as Moonshane's preference for 70deg or less. I honestly can't take in the full 82deg of the ES eyepieces, which is great if that's what you want. The ES 82's are fantastic eyepieces and great value for the money. You just have to know when best to use that wider field of view and not expect to take in the entire field.

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In all honesty, you cannot really go badly wrong these days with the quality available. If it's feasible to buy used then this is a good option as you can buy, try and the keep or sell at little or no loss if you change your mind and want to try something else. I have not used either of the eyepieces referred to but the ES do get great reviews. The Hyperions are not bad either according to reviews but I suspected suited more to scopes of f6 or higher focal ratio.

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I have used both the Hyperions and the ES 82’ range. I actually swapped all the former for the latter. I just couldn’t live with the eye relief on the Hyperions or the weird eyecup.

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I never really thought about what is my preferred eye relief, but now that you brought up the topic - it looks like I prefer around 20mm eye relief. I'm not wearing glasses btw.

Just went and checked specs of couple of eyepieces, ones that are most comfortable for me to use and they all have around 20mm eye relief.

I've god 11mm ES82 and it is great eyepiece - very sharp. I don't care much for 82deg FOV - I think it is too much - I'm perfectly happy with fields of around 68 degrees. ES82 11 also took me a bit of getting used to it. Due to a bit longer eyelashes there is awkward sense of always brushing them against eye lens of ES82 11mm.

ES68 28mm for example I find marvelous eyepiece, I like it's eye relief very much. ES68 16mm has a bit less eye relief and it's starting to feel like ES82 11 - a bit awkward - probably due to similar eye relief of ES82 11mm - at 11.9mm.

Due to this eyelashes issue, I found that using for example 6mm Ortho is less awkward than above eyepieces although it has less eye relief. 6mm Ortho has very short eye relief - around 5mm, and that presents a challenge - there is certain fatigue when using it for longer times, but since eye lens is very small - I don't get same awkward feel of eyelashes hitting it.

Having said all this - I would rather choose sharp eyepiece with eye relief issues than comfortable one with aberrations. One can probably get used to short eye relief but you can't train your self to see sharper image.

Best option, of course, is sharp eyepiece with appropriate eye relief, good transmission and contrast, minimal scatter, decent FOV (60-70 deg range) and reasonably priced :D - anyone knows such eyepieces? :D

 

 

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I too had my eyelashes brushing the rubber of the eyecup of the ES 82°.
The image is sharp, but with this eyepiece the usable eye relief is much shorter
than the stated eye relief, which is measured from the glass.
ES11.png.adbb88ba802161330337a1827a8feee7.pngES 82°
I returned the ES 82° and got a 12mm Delos instead. Very fine, but really expensive.

I never considered Baader's Hyperions because I have an f/5 telescope. Their
Morpheus line is amazing though.
 

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3 hours ago, Hapii said:

PS: People who are wering glasses doesn't count :D.

Wow.  Us astigmatism-afflicted observers don't count.  I thought it would never come to this on SGL. 😉

Be that as it may, I've found that long eye relief eyepieces help immensely when sharing the view because others don't have to take off their glasses and refocus the view since everyone observing is corrected for distance viewing.  That, and you don't get eye makeup smeared on your eye cup. 🤮

4 hours ago, Hapii said:

If you have to choose between 82° eyepiece with 13mm eye relief VS a 68° EP with 20mm eye relief (assuming they have same build quality, and price)

What would you prioritise for your viewings ?
At what point would you consider a poor eye relief ? below 15mm ? Lower ?
Does a poor eye relief is even worse when the Fov is big?

To address your specific questions:

I would definitely go with whatever AFOV is most easy to take in at a glance.  If you have to jam your eye into your eyepiece to see the fieldstop, that gets old in a hurry.  Thus, I'd go with the narrower, longer eye relief any day.

Poor usable eye relief starts around 14mm to 15mm for me with eyeglasses.  By usable, I mean the measured eye relief from the top of the folded down or removed eye cup.  The Delos, XW, XL, LV, and ES-92 lines all claim 20mm of eye relief, but the usable eye relief is actually closer to 18mm or even 17mm for some focal lengths.  The Morpheus line actually have 19mm to 22mm of usable eye relief thanks to the nearly complete lack of eye lens recession and very thin eye cups.  The XW and ES-92 lines in particular both lose 2mm or more usable ER due to eye lens recession.

If I'm working at sub-1mm exit pupils, I can sort of tolerate my uncorrected astigmatism and remove my eyeglasses.  I can then use 7mm to 9mm of usable ER eyepieces comfortably as is the case with my Speers-Waler 5-8mm zoom.  Even without glasses, the 4mm and 5mm usable ER of my 9mm and 12.5mm Kellners, respectively, is still extremely uncomfortable.  They came with my ST-80 years ago and have no real resale value, so I hang onto them for a quick reminder of how nice $200 to $500 eyepieces really are.  My 12mm ES-92 positively dwarfs that 12.5mm Kellner, though. 🤣

As an example of poor eye relief with a large AFOV, the above mentioned SW zoom has a constant 78 degree measured AFOV.  With eyeglasses on, I can see maybe 60 degrees of that, so it is frustrating knowing I'm leaving AFOV on the table unviewed.  It's still perfectly usable, but annoying none-the-less.  With narrow AFOV eyepieces like the Kellners, the viewing becomes super narrow with eyeglasses on.  I can see maybe 20 degrees at most of the 42 degree AFOV.  This makes manual tracking at high powers all but impossible.  I can see where when using a tracking mount and viewing planets, it could be an acceptable use case.

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I’ll venture to say that I think too much attention is paid to eye-relief!  It would be other performance characteristics of an eyepiece, like sharpness, contrast, transmission, etc, that would persuade me to buy it or not. (I don’t wear specs when observing - if I did, perhaps I’d feel differently). I own a number of eyepieces with intentionally ‘comfortable’ eye relief (Delos), some with weird eyerelief (28mm RKE) and quite a lot with short eyerelief (orthos, plossls and a mono). In some important ways and applications, this last group outperforms the others and for me that would be the basis for choosing them or not. 

I’m also with Moonshane in not favouring the 100 degree options. I have a 13mm Ethos and, extraordinary feat of design and execution as it is, I wouldn’t buy one again.  

As for your specific choice, I’ve not owned that ES, though I have the 24mm 68 degree and quite like it. I have owned Hyperions but thought the performance was very ordinary and sold them.  I’ve used the later Morpheus and think they’re a very big step up. If it’s really just between the two you mention though, I’d go for the ES.

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I’m with Moonshane on this. Without glasses I find that anything between about 10-15mm of advertised ER (real ER being a few mm less) is about perfect. Less and my eyelashes start to brush the lens, more and it gets difficult to hold the view. This is why most 20mm ER EPs (geared towards eyeglass users) tend to have adjustable eye guards. 

In your case I’d lean towards the 82 degree/13mm ER option, but I’d read reviews of that particular EP to make sure that users find it comfortable before buying. 

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I have gone both ways with eye relief.

Short, Very Short and Eyeball on Eye-lens short.
Longer at 15-20mm s well.

In all honesty I like something between 15-20 mm Eye-relief, but this is a very personal thing.
Until you try them all, you will not know and just one try will not be enough,
you need to do some observing on varying target to decide.

The worst thing is you might like both and end up keeping both types of EP.

 

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Agree, it is personal. Comfort is nice and makes for effective observing - but I can live with a bit of discomfort if an eyepiece is giving an edge in performance.  Not to say that being uncomfortable is an essential requirement!

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On 04/01/2019 at 11:41, Ben the Ignorant said:

82°. 13mm or 14mm eye relief are enough, and the Hyperion line is not as sharp as the Explore 82° line, more field doesn't necessarily cause more edge aberration. I own the 10mm Hyperion, some greenish fringing happens around everything bright. Center sharpness is okay but the Hyperion line is not competitive anymore, 120€ for a 68° when many very good 82°'sell for 95€ is not a bargain. I paid only 90€ for my Hyperion in 2013 but now I'd go for an Explore or its Opticstar clone.

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_322

Add 11% to the price in £ to convert it to €.

The Hyperions were something of a bargain when they first came out, I think I paid around £65 for my early ones and there wasn't much else available for that price giving that FOV.

Baader must have seen this and the price very quickly went up to £75 ish, not the worst deal in the world but getting closer to other, competing, options. Since then they've drifted up while better options have come along at a similar price point.

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I admit to having a real soft spot for the 24mm Hyperion after comparing it alongside a 24mm Panoptic in three great scopes. My friend Derek bought the 24 Pan for use in his Sky 90, and on one night sometime within the last 18 months or so, Derek and I had taken our scopes over to my friend paulastro's , where we enjoyed an evening observing, and comparing scopes and eyepieces. Derek took his Sky 90, I had taken along my FC100DC, and Paul was using an excellent 102mm AstroTech ED. Wanting to simplify my eyepiece collection I was particularly interested in the 24mm Panoptic, but comparing it in all three scopes the eye relief felt restrictive and the edge of the field was pretty poor considering the high price of the eyepiece. By contrast, the 24mm Hyperion had a larger eye lens, felt noticeably more comfortable on eye relief, and most importantly for me, was sharp to the edge. And it costs a fraction of the price of the Panoptic. Derek remained happy with his 24mm Pan, but both Paul and I felt it was by far the worst performer at the edge of field, less comfortable than the Hyperion and considerably overpriced. Whatever the spec of an eyepiece, I suppose in an ideal world it would be best to test drive eyepieces alongside eachother before parting with hard earned cash. 

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I have the 24mm Hyperion and it gets a lot of use in my ED120. Optically it's different from the rest of the range so it's hard to judge the rest from it's performance.

BTW does anyone know what happened to the 3.5mm Hyperion? It doesn't seem available anywhere these days

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I've liked the Hyperions that I've used, but not so much when they are put into a scope faster than around F/6.

One of the 1st reviews I did here was to compare Hyperions to Vixen LVW's. Vixen UK actually put it on their website:

https://www.vixenoptics.co.uk/Pages/lvw_review.html

 

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If you're observing in colder temperatures then having a little extra eye relief can prevent the eye lens from fogging.  I think most modern eyepieces add an extra element or two to achieve this, plus apparent field is wider as well, compared to 4 element eyepieces.  I own a few 58 degree AFOV eyepieces that seem just as wide ( maybe even slightly wider) than a couple 25 year old 67 degree Super Wide Angle eyepieces, so that's a bit puzzling to me.  I wear glasses for driving but prefer not to while observing so extreme wide fields above 82 degrees wouldn't be for me.

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On 06/01/2019 at 00:41, davejlec said:

....  I own a few 58 degree AFOV eyepieces that seem just as wide ( maybe even slightly wider) than a couple 25 year old 67 degree Super Wide Angle eyepieces, so that's a bit puzzling to me. ...

Some eyepiece brands were / are a little "optomistic" about their apparent field of view ..... Some of the Meade 4000 UWA's, for example, were certainly not 80+ degree AFoV eyepieces.

 

 

 

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1 hour ago, John said:

Some eyepiece brands were / are a little "optomistic" about their apparent field of view ..... Some of the Meade 4000 UWA's, for example, were certainly not 80+ degree AFoV eyepieces.

 

 

 

I have the smoothie original 14mm Meade 4000 UWA.  I measured the AFOV to be 80 degrees via projection rather than the claimed 84 degrees.  After measuring the effective field stop using a yard stick and some math (19.5mm), the effective AFOV is also 80 degrees, so distortion across the field is practically non-existent.  However, it needs updated coatings and massively improved stray light control to compete with modern offerings like the 14mm Morpheus.  Still, it has an absolutely flat field, which was quite an accomplishment for its day.

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12 hours ago, John said:

Some eyepiece brands were / are a little "optomistic" about their apparent field of view ..... Some of the Meade 4000 UWA's, for example, were certainly not 80+ degree AFoV eyepieces.

 

 

 

 John, Good to know that about the AFoV's not always being as advertised.  Wasn't sure if the 58 degrees were more than advertised or the 67 degree were less than advertised- thanks!   

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I think I remember reading that the 21mm Hyperion is a lot closer to 60 Degs than 68 which, if true, makes it a little redundant as the 17mm Hyperion gives that same FOV at a higher magnification.

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Thanks everyone !

I can see that this question is a little subjective of course because each person have a comfort preference. 

The thing is i don't really know what would be my best comfort eye relief because the only eyepiece that came with my celestron nexstar 4SE is a 25mm plossl but i can't find the exact same on internet so i don't know it's eye relief !
On the EP it's only writed : Celestron 25mm PLOSSL FULLY COATED china

After some reflection i will actually drop the idea on buying ES82 or Hyperion and go for much cheaper EP at first, because i understood that in faster scopes like mine ( f/13 ) it's much more forgiving.

Thank you all

 

 

Edited by Hapii
missing info

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The eye relief on a 25mm Plossl will be around 18mm, HTH.

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