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Celestron Luminnos eyepiece, 31mm is a pain

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#1 RichA

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Posted 25 June 2015 - 01:10 AM

Make that "Luminos."  Case in point;  huge low power, ultrawide field eyepiece.  The eye relief in some cases may be a claimed 20mm, but in order to see the entire field, and not hit kidney-beaning or simply lose the outer edge, you need to keep your distance DEAD steady.  Very uncomfortable.


Edited by RichA, 25 June 2015 - 01:11 AM.


#2 Mitrovarr

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Posted 25 June 2015 - 01:27 AM

Is there really a good option for that combination of focal length and field width? The 31mm Nagler is just too expensive for most people. I have a 38mm Q70 that is very nice to use, but it only has a 70 degree field and doesn't fare well in fast scopes (it's great in SCTs though).


Edited by Mitrovarr, 25 June 2015 - 01:28 AM.


#3 RichA

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Posted 25 June 2015 - 02:22 AM

I honestly do not know if there is a good option.  It's possible that we are only "kidding ourselves" that such a f.l. and field can be contained by a 2" design.  I once saw the Pentax 60mm eyepiece.  It had at least a 3" barrel.  Perhaps it's time they moved to a 3" diagonal?



#4 Scanning4Comets

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Posted 25 June 2015 - 02:28 AM

The 30mm ES 82 is another option. The eye lens is recessed a bit and there are no blackouts when using that eyepiece. The other option is a Meade 24mm Series 5000 UWA. Both work very good in fast scopes, and there are no problems like you mentioned when using both these eyepieces. The 30mm can be had at a really good price on the used market....same goes for the Meade 24mm UWA.

 

CS!


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#5 jetstream

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Posted 25 June 2015 - 08:20 AM

The 30mm ES 82 is an excellent eyepiece and it is a permanent EP in the arsenal, unless they come out with a 30mm Ethos... :lol:


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#6 Jon Isaacs

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Posted 25 June 2015 - 08:40 AM

I have no problem position ing my eye with the 31 Nagler

 

I honestly do not know if there is a good option.  It's possible that we are only "kidding ourselves" that such a f.l. and field can be contained by a 2" design.  I once saw the Pentax 60mm eyepiece.  It had at least a 3" barrel.  Perhaps it's time they moved to a 3" diagonal?

 

I don't know of any optical reason why eyepieces like the 31 Nagler or the 30 mm Ethos require anything more than a 2 inch format. A 60 mm eyepiece with anything greater than a 44 degree AFoV needs a larger barrel.

 

Looking at the 31 mm Luminous, the obvious difference from the other two is large diameter flat top where as the other two have a more ergonomic torpedo shape, it's easier to look through the torpedo shape because your nose doesn't get in the way. The 27 mm eyep relief is long enough that some observers will probably have difficulty with eye placement.

 

I think this is a design issue with the 31 mm Luminous..

 

Jon


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#7 Starman1

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Posted 25 June 2015 - 10:10 AM

Note that a 30mm Ethos would be a 3" eyepiece if it existed.

A 30mm 100 degree Explore Scientific does exist, and it is 3".


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#8 Usquebae

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Posted 25 June 2015 - 10:44 AM

I feel the OP's pain.  I have now modified the eye-cup on, I believe, 16 of my EPs, with much mixing and matching of parts.  Most recently I stuck the rubber bit from a Z100 EP onto the top of the raised eye cup of a 35 Panoptic, adding approximately 5mm in height, and now the infamously fussy 35 Pan is a perfect fit to my eye.

 

As for the 31 Luminos, the first step is to decloak the beast, which knocks off a full pound of weight, and also fixes the nose-room issue.  Building a housing above the lens should not prove to difficult.  In place of rubber you can use couple layers of sturdy duct tape cut to form, with scopestuff felt inside to kill reflections.  I don't recall what I used to build the height (it's covered in tape now - hot pink!) but it measures 25 up from the shoulder of the decloaked housing.  Very comfy now.

 

My new 31 Luminos cap (and many others) is made from layered, brightly colored duct tape.


Edited by Usquebae, 25 June 2015 - 10:45 AM.

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#9 Starman1

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Posted 25 June 2015 - 02:02 PM

If you must bury your eye in an eyecup, you'll have to make your own eyecup because the eye relief is long and NO eyecup will be long enough, even the after-market accordion ones.
Buy a bicycle inner tube the same diameter as the eyepiece.  (Say the eyepiece is 1.5" in O.D.--get any size tube with a 1.25-1.5" width).  Cut out a 3" section and clean it well.
Pull it over the top of the eyepiece and pull it down about 1/2".  Then, fold over the top so it overlaps the part already on the eyepiece and pull it down until it's equal.  If that's too tall, pull it down more until you achieve the perfect height for the eyecup.
See http://www.cloudynig...ce-rubber-cups/  and go down to post #8.  His were pulled down to make them short.  But they can be as long as you want.  And, you can get a hundred eyecups out of one inner tube!


Edited by Starman1, 25 June 2015 - 02:04 PM.


#10 Mitrovarr

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Posted 25 June 2015 - 07:29 PM

It's good to know the 30mm ES 82 is a solid performer. I'll keep an eye out for one someday when I've got a few extra hundred dollars to burn on one. I did some calculations once that showed (well, I think) that the greatest TFOV is achieved with a 55mm plossl, then a 41 panoptic-type, a 31mm nagler-type, and finally a 21mm ethos-type. A 30mm ES 82 would be a good point of balance between having a good TFOV, a good AFOV, and a fairly reasonable price point.

 

I wonder if the Meade 30mm series 5000 UWA was any good? It's discontinued now, but a lot of people say some of them had the same optics as some of the ES eyepieces. Maybe it was the same?



#11 Jon Isaacs

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Posted 25 June 2015 - 08:42 PM

It's good to know the 30mm ES 82 is a solid performer. I'll keep an eye out for one someday when I've got a few extra hundred dollars to burn on one. I did some calculations once that showed (well, I think) that the greatest TFOV is achieved with a 55mm plossl, then a 41 panoptic-type, a 31mm nagler-type, and finally a 21mm ethos-type. A 30mm ES 82 would be a good point of balance between having a good TFOV, a good AFOV, and a fairly reasonable price point.

 

I wonder if the Meade 30mm series 5000 UWA was any good? It's discontinued now, but a lot of people say some of them had the same optics as some of the ES eyepieces. Maybe it was the same?

 

Optically, I believe it is the same. Mechanically, it has much in common with the Luminos, a large diameter flat top barrel. 

 

I find that torpedo shaped upper barrels are best with large eyepieces, they allow me to position my eye without the eyepiece contacting my nose.. With small eyepieces, I like a flat top, either one fits in my eye socket area but flat top gives me a little protection.

 

Jon



#12 rowdy388

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Posted 25 June 2015 - 08:49 PM

I have the Meade 30 UWA, a 3 pound beast. Yes, the optics are terrific but the ergonomics
are worst than the ES because the eyecup is almost the size of a dinner plate. A human
sized face can not look straight into it, you have to turn your head sideways and look
through at an angle. Good news is the eyecup is easy to take off and they are cheap and
often come up second hand.
Dave Y

Edit: Usquebae, I read with interest how you modded (post #8) the top of your eyecup to fit. I actually did the same with my Meade 30UWA without removing that huge top. The reason being I like to have an eyecup to hold my head correctly and having no
eyecup is cold against my face in the winter. My fix was to trap a smaller fold up
eyecup under the Meade's twist up cup. The smaller cup stays in place and I use a
smaller cap to cover it with.
Dave Y

Edited by rowdy388, 25 June 2015 - 09:08 PM.


#13 Scanning4Comets

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Posted 26 June 2015 - 03:03 AM

It's good to know the 30mm ES 82 is a solid performer. I'll keep an eye out for one someday when I've got a few extra hundred dollars to burn on one. I did some calculations once that showed (well, I think) that the greatest TFOV is achieved with a 55mm plossl, then a 41 panoptic-type, a 31mm nagler-type, and finally a 21mm ethos-type. A 30mm ES 82 would be a good point of balance between having a good TFOV, a good AFOV, and a fairly reasonable price point.

 

I wonder if the Meade 30mm series 5000 UWA was any good? It's discontinued now, but a lot of people say some of them had the same optics as some of the ES eyepieces. Maybe it was the same?

 

A really good observing friend of mine, (beatlejuice), and I did a test between these exact two eyepieces over the course of a night and optically there was no difference at all when we viewed through them. However, ergonomically, the 30mm Meade 5000, (with the big, bulbous eyecup removed), was easier to get in there because he top eye lens is almost flush with the housing making it much easier to take in the entire FOV. It was just more comfortable. If you want a 30mm Meade 5000, I suggest looking for one on the used market, and take your time as they do come up.

 

Cheers,


Edited by Scanning4Comets, 26 June 2015 - 03:53 AM.


#14 rmollise

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Posted 27 June 2015 - 08:48 AM

Make that "Luminos."  Case in point;  huge low power, ultrawide field eyepiece.  The eye relief in some cases may be a claimed 20mm, but in order to see the entire field, and not hit kidney-beaning or simply lose the outer edge, you need to keep your distance DEAD steady.  Very uncomfortable.

 

Frankly, most eyepieces in this range are a pain, including even the vaunted 35 Pan. Hated its eye-relief/blackout/kidney-beaning characteristics when I first got it. I learned to use it and love it, however, and have had it for about 15 years now. :)



#15 russell23

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Posted 27 June 2015 - 09:17 AM

Is there really a good option for that combination of focal length and field width? The 31mm Nagler is just too expensive for most people. I have a 38mm Q70 that is very nice to use, but it only has a 70 degree field and doesn't fare well in fast scopes (it's great in SCTs though).

 

This is why I think the 28mm ES68 is such a valuable option on the market (and the 27mm Pan too).   The 28mm ES68 is not as affordable as it used to be, but it is still a good option for many people.  It weigh's 16oz, is sharp, provides bright views, no blackouts, no EOFB, will have a nice exit pupil in just about any scope, and it barlows nicely if you need that option.   No it does not max out the TFOV, but it is still useful as a widest TFOV option in many scopes if you are unhappy with the even longer FL options. 

 

I think a lot of people might find that if they give up a little bit in the max TFOV chase, they would be much happier with the 28mm ES68 or the 27mm Pan than  the wider TFOV eyepieces they are using that they find unsatisfactory for various reasons.

 

Dave


Edited by russell23, 27 June 2015 - 09:19 AM.


#16 Jon Isaacs

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Posted 27 June 2015 - 09:51 AM

I think a lot of people might find that if they give up a little bit in the max TFOV chase, they would be much happier with the 28mm ES68 or the 27mm Pan than  the wider TFOV eyepieces they are using that they find unsatisfactory for various reasons.

 


 The 27 mm Pan and 28 mm ES provide less than 70% of the maximum possible TFoV, for me, that's a lot. Its not a whole lot more that their 1.25 inch 24mm versions. I think 35 mm Panoptic class is a nice balance..

 

Jon


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#17 csrlice12

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Posted 27 June 2015 - 10:49 AM

I had no problems with the mushroom top ES82 30mm (or the 24mm) eyepieces.  Really liked the views.  They were heavy beasts and looked like a giant photon-sucking tick on the focuser of the scope (and that's a pretty good description of how they work).  Only sold them after I got the XWs, till then, the ES82 24mm was my most used eyepiece.



#18 otocycle

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Posted 27 June 2015 - 12:16 PM

I have the all the Luminos eyepieces (some in pairs) except for the 31mm, because the 31mm Nagler was already in the eyepiece case more than a decade before.   It took a little getting used to their flat top design...extending the "eyecup" doesn't help much at all.   The 23mm Luminos is almost as bulky as the 31mm, but it actually punches well above its deeply discounted new/used price point.

 

I went back and forth on the 31mm Nagler and 30ES82, settling on the latter because of cost savings, infrequent use, and more time spent on imaging compared to visual these days.   Still, if a 31mm Luminos came up for sale at a crazy low price, I would bite just to see the difference and maybe complete the set.


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#19 tjay

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Posted 27 June 2015 - 04:10 PM

The 30mm ES 82 is another option. The eye lens is recessed a bit and there are no blackouts when using that eyepiece. The other option is a Meade 24mm Series 5000 UWA. Both work very good in fast scopes, and there are no problems like you mentioned when using both these eyepieces. The 30mm can be had at a really good price on the used market....same goes for the Meade 24mm UWA.

 

CS!

 

I count myself lucky to have the Meade Series 5000  24mm and 30mm UWA.  Very nice eyepieces in every scope I've used them with.


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#20 russell23

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Posted 27 June 2015 - 06:23 PM

 

I think a lot of people might find that if they give up a little bit in the max TFOV chase, they would be much happier with the 28mm ES68 or the 27mm Pan than  the wider TFOV eyepieces they are using that they find unsatisfactory for various reasons.

 

 The 27 mm Pan and 28 mm ES provide less than 70% of the maximum possible TFoV, for me, that's a lot. Its not a whole lot more that their 1.25 inch 24mm versions. I think 35 mm Panoptic class is a nice balance..

 

Jon

 

 

That is very true.    What I am suggesting is that some people might be happier with their largest TFOV eyepiece if it was the 28mm ES68 rather than chasing the maximum TFOV options.  

 

As an example here are the main long FL 2" options with my 120mm f/7.5:

 

31mm Nagler  $650, 35.2 oz, 2.83 deg TFOV

35mm Pan      $380, 25.6 oz, 2.65 deg TFOV

30mm ES82   $340, 35 oz, 2.73 deg TFOV

34mm ES68   $300, 24 oz, 2.57 deg TFOV

36mm Siebert $229, ~12 oz, 2.88 deg TFOV

35mm Levenhuk $220, 17.3oz, 2.65 deg TFOV

36mm Baader $219, 13.8 oz, 2.88 deg TFOV

35mm Bresser 70 $140, 18.3 oz, 2.72 deg TFOV

38mm Agena SWA   $95, 21.3 oz, 2.95 deg TFOV

 

28mm ES68 $225, 16.0 oz, 2.12 deg TFOV

 

Optically, the best options might be the 31mm Nagler and the 35mm Pan, but they are expensive and heavy which will knock them out for many people.  The 34mm ES68 and 30mm ES82 are also heavy and cost $300+ (and the 34mm ES68 is not nearly as good as the 28mm ES68 optically and ergonomically).   The 36mm Siebert is about the same cost as the 28mm ES68 and light, but it is not as good as the 28mm ES68 optically and you might not be able to get one because Harry is so busy.  The 36mm Baader about the same cost and weight as the 28mm ES68 but is it as good optically?  Probably not as good near the edges from the reports I've read.

 

The 35mm Bresser and Levenhuk are somewhat unknown quantities.  I doubt the 35mm Bresser with 5 elements is as good as the 28mm ES68.    The Levenhuk looks to be the same as the Astrotech Titan II ED eyepieces which were a little short on eye relief for their FL and not really much better than lower cost options for edge performance.

 

Finally there is the 38mm Agena SWA, Orion Q70 - terrible edge performance in many scopes.

 

So yes - the 28mm ES68 gives up some TFOV, but it costs less than the quality wider TFOV options, is lighter, is comfortable (no blackouts), has good edge performance and no EOFB.   And you will get a larger image scale and smaller exit pupil compared to the other options listed above.   When you look at all that, there is likely a set of people that might be better off going with the 28mm ES68 than the heavier, more expensive, longer FL options that nearly max out the possible TFOV. 

 

If you can afford the 31mm Nagler or the 35mm Pan and don't mind the weight then great, but if those issues are problematic the 28mm ES68 is probably the next best eyepiece of those listed above.  Yet many people might not consider that option because they are thinking in terms of maxing out the TFOV rather than maxing out the quality-TFOV.

 

Dave


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#21 Jon Isaacs

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Posted 27 June 2015 - 06:52 PM

Optically, the best options might be the 31mm Nagler and the 35mm Pan, but they are expensive and heavy which will knock them out for many people........if you can afford the 31mm Nagler or the 35mm Pan and don't mind the weight then great, but if those issues are problematic the 28mm ES68 is probably the next best eyepiece of those listed above.  Yet many people might not consider that option because they are thinking in terms of maxing out the TFOV rather than maxing out the quality-TFOV. 

 

 

 

Dave:

 

An excellent summary.

 

I point to the 35 mm Panoptic because it does offer excellent views even in fast scopes, it is heavy but not as heavy as some of the others, it offers a wide true field of view and finally, they are frequently available on the used market for about $250, you get a world class eyepiece that is reasonably affordable.

 

Jon


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#22 SeattleScott

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Posted 28 June 2015 - 12:17 AM

The 42mm vixen LVW is a lightweight, premium eyepiece that performs well in fast scopes (at least the 65* AFOV version. I suspect the 72* could not be as well corrected but can't speak from experience). It isn't sharp to the edge in my F4.8 but it beats the heck out of my 38mm agena SWA. And little issue with eye placement or losing the edge at F4.8. It does have some issues with losing the edge in my Cat as I sweep, not surprisingly. But with my fast reflector, the exit pupil is so oversized it doesn't seem to be a problem!  Background sky is a bit bright though. And the eyepiece can be on the pricey side new, although not Terminagler pricey. Really nice ep though. 



#23 Usquebae

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Posted 28 June 2015 - 10:49 AM

 I suspect the 72* could not be as well corrected but can't speak from experience

 

I think I recall that the 72° was actually a misprint on early models of the EP, and that all are in fact 65° no matter what the housing claims.  It might have been a discussion on Stargazer's Lounge.



#24 Herr Ointment

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Posted 28 June 2015 - 11:01 AM

A de-cloaked 31mm Axiom (the Luminos predecessor) is my favorite ep in my C11.

 

Ridding it of the shell and making an inner tube eye thingy made it so much better.

 

Bonus? Turn the shell into something useful!

 

cn44.jpg

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#25 Scanning4Comets

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Posted 29 June 2015 - 02:06 PM

A de-cloaked 31mm Axiom (the Luminos predecessor) is my favorite ep in my C11.

 

Ridding it of the shell and making an inner tube eye thingy made it so much better.

 

Bonus? Turn the shell into something useful!

 

LOL! At least it has some use!!!! :lol:




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