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31mm Celestron Luminos eyepiece, one of worst I've used

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#26 Tank

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Posted 10 July 2018 - 12:12 PM

Luminos on axis I thought was good

other than that cant say to much good about it


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#27 Adun

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Posted 10 July 2018 - 03:21 PM

I've heard too much criticism of the Luminos to consider them anymore. The Meade MWA series is the same way. If so many people dislike it so much... it must be doing something pretty wrong. Especially at the Luminos' low price point - people would be willing to cut it a lot of slack. I guess some people like them, but even then they'll usually qualify it.

 

As far as cheap 82 deg. eyepieces go, I think it's much better to go up to the next tier and get a Meade UWA or ES 82. I have a Meade UWA (the 20mm) and I like it a lot. I think the main advantage with the ES series is that you don't get that stupid twist-up eyecup.

 

It's hard to thread those 82º waters when you are so budget conscious and lack first-hand experience with the more expensive alternatives.

 

I skipped the Luminos altogether and went for Meade UWAs. Despite the MWAs being tempting on price (only $169!) I avoided them because there is just no forum love for them, while the (new model, waterproof) UWAs feel "proven" once you read what's out there.

 

I really like my UWAs, (5.5, 8.8 and 20) specially on my F4.7 dob, but I'm not so sure about getting the 14mm, there's less love for it, although even the 14mm ES82 has it's critics, and it seems a more challenging FL to design.


Edited by Adun, 10 July 2018 - 03:22 PM.


#28 nicoledoula

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Posted 10 July 2018 - 04:10 PM

Even a 26mm GSO kellner is good on axis. No one can call any other EP worse, but maybe the 31mm Luminos is close.  That same 26mm K works pretty good for terrestrial, who'da thunk? 


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#29 Jon Isaacs

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Posted 10 July 2018 - 08:56 PM

I've heard this a lot, but I haven't seen it myself. It may be sample variation, which, if true, would be a good reason not to buy it unless one wanted to spend time trying several samples and sending the bad ones back.

 

 

I had the 23mm Luminos for a while.  Like many/most, I found the EFoB brightness excessive.  I actually experimented with smaller field stops to try it curb it.  A 33mm did help some but it still was quite bothersome.  

 

I have been following the EFoB issue on this forum since the beginning.  I first noticed it about 10 years ago with the Orion 13mm Stratus.  It just so happened that the 13mm Stratus and the 16mm Type 2 Nagler are about the same size so in the dark, it was possible to mistake one for the other.  This really was a blind test because I would accidentally pickup the Nagler thinking I had the Stratus.

 

It usually took me about 3 seconds to realize I had made a mistake.  First I would think:  "Wow, I don't know what I have been thinking, this Stratus really is a very good eyepiece, it's sharp across the field and it's evenly illuminated across the field."  And then I realized, I had the 16mm Nagler. 

 

I personally think it's an issue of awareness, of expectations.  When one has expectations of and experience with evenly illuminated fields, the bright edge of eyepieces like the 23mm Luminos seem very apparent.

 

That's my 2 cents.  

 

Jon


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#30 Miranda2525

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Posted 10 July 2018 - 09:11 PM

That's interesting--I'll have to try the 31mm sometime if I can find one at a local astronomy club. I wonder if deshrouding it would help? It would certainly make it lighter (but not as light as my GSO 30mm SV). There have been so many complaints of recent (i.e. past decade) Celestron EPs that I believe you--some are probably just design duds, others (the X-Cels, I believe) apparently come new from the factory plagued with dust and other QC issues. My new Omni Plossls, like my Luminos, are fine, however.

Deshrouding it won't do anything. It's the internal baffling that is not done right in this EP.


Edited by Miranda2525, 10 July 2018 - 09:11 PM.


#31 jrbarnett

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Posted 10 July 2018 - 09:27 PM

Thomasr - I have to agree with you. I have 3 Luminos EPs and can find no major fault with any of them. Maybe they are built with the longer f/l SCT scopes in mind?

 

I also find the 15mm to be a valuable member of my EP collection. I haven't used the 10mm much mostly because the weather and sky around Ohio this summer has been pitiful.

 

The 31mm, one that has received more than its share of negative reviews around here actually gave me a very impressive view of Jupiter and a moon transit. Maybe it was that I was only looking at the center of the field but it was very sharp and clear. I was able to see Ganymede in transit even though it was only at about 75x with my C 9.25". At first I thought it was a shadow but it was the actual moon going across the disc.

 

I'm sure it pales compared to Televue but for the money I've been quite satisfied with them. The 31mm is a giant though, very heavy and fat in the middle. My 40mm EP is much lighter though it is only a 68* so I suppose that isn't a completely fair comparison.

When I bought my C9.25 EdgeHD it came with a 23mm Luminos.  I could not give that eyepiece away fast enough.  The guy I gave it to, my Dob loving buddy Jeff Cooke, likewise didn't keep it long - apparently free was too steep a price to pay for such suffering.

 

Kellners work fine in SCTs.  I don't think it is possible to optimize for an SCT to be honest.  The design is fairly undemanding on eyepieces.  I'm also not a Televue fanboy.  Like most eyepiece firms, they have some winners and some "also rans".  I like Type 5s, Type 6s, Ethos, Panoptics and Delos, personally.  Not a fan of Radians, Type 4s, Delites.  Agnostic about Plossls.  Like the novelty of the Nagler Zoom, but not its performance relative to most fixed focal length eyepieces.

 

Best,

 

Jim


Edited by jrbarnett, 10 July 2018 - 09:28 PM.

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#32 BigC

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Posted 13 July 2018 - 07:55 PM

Deshrouding it won't do anything. It's the internal baffling that is not done right in this EP.

Deshrouding loses little weight  but makes it look uglier in my opinion.

 

Deshrouding also removes the ability to set the eyecup at your favored height.

 

Experimenting with one of each I find the eyecup  helps greatly in placing my eye at the point where kidney beaning is absent.

 

Edge of field brightness is evident but acceptable tradeoff for the wide view.

 

My opinions with my eyes,experience,and budget;your results and expectations  may be different.



#33 MrJones

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Posted 13 July 2018 - 10:23 PM

I like a purist. I found the shroud and cap that are immaculate and the stickers covering the screws, one of which is slightly blemished. I will send them along so that you can enjoy a fully authentic Luminos experience as the USPS donkey currently servicing the Southern Indiana route was cheaper than expected. smile.gif


Edited by MrJones, 13 July 2018 - 10:25 PM.

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#34 dustyc

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Posted 14 July 2018 - 07:41 PM

My scope came with the 23mm luminos. I just use it for outreach. I thought that maybe the eofb was due to urban light pollution but getting out to a dark site didn't make any difference.


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#35 Jon Isaacs

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Posted 14 July 2018 - 07:55 PM

Deshrouding loses little weight  but makes it look uglier in my opinion.

 

Deshrouding also removes the ability to set the eyecup at your favored height.

 

Experimenting with one of each I find the eyecup  helps greatly in placing my eye at the point where kidney beaning is absent.

 

Edge of field brightness is evident but acceptable tradeoff for the wide view.

 

My opinions with my eyes,experience,and budget;your results and expectations  may be different.

 

It sounds good in theory but those massive twist up eyecups just get in my way of positioning my eye . If they could be twisted down,  they might have some use. 

 

Some people have trouble with eye placement .  That's not me. . 

 

Jon



#36 mark379

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Posted 23 July 2018 - 08:51 AM

Did you fine EOFB  less bothersome in heavy light pollution?

My scope came with the 23mm luminos. I just use it for outreach. I thought that maybe the eofb was due to urban light pollution but getting out to a dark site didn't make any difference.



#37 Miranda2525

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Posted 23 July 2018 - 06:08 PM

Did you fine EOFB  less bothersome in heavy light pollution?

My take, is that it would actually be worse.



#38 mark379

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Posted 24 July 2018 - 08:45 AM

I wonder if it will be worse or just  blend together and bee mess noticeable?

My take, is that it would actually be worse.



#39 Jon Isaacs

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Posted 24 July 2018 - 09:44 AM

Did you fine EOFB  less bothersome in heavy light pollution?

 

I found it objectionable under dark skies as well as under light polluted skies. I didn't really notice any difference.

 

But it's worth stepping back for some perspective.

 

My 23 mm Luminos was trying the fly with the eagles, it was up against some very tough competition, the 21 mm Ethos, 22mm Panoptic, and the 31 mm Nagler.  These eyepieces are very well corrected in my fast scopes and are evenly illuminated across the field of view.. no EoFB..

 

How would I feel about the 23 mm Luminos if that's what I had?

 

I'd use it, that's for sure. And I'd probably like it better than the Erfle like derivatives that are the alternatives.

 

Jon


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#40 mark379

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Posted 24 July 2018 - 09:52 AM

Jon,

 That actually answers my question  for the most part     Thank you !

 My main thought is to use this Ep for  out reach  in my clubs heavily light polluted main observing  area  with a 10 inch GSO F5 dob. 

 I guess my thought was would it make an object such as a nebula  disappear closer to the outer edges???

 I haven’t tested it yet under this condition but was wonderIng.  From what it sounds, it’s going to be better than the 25 mm erfle  currently being used by this telescope.  I was going to do the change out in September when our public telescope night begin at  Montclair  state university.  

 Under an orange zone where I’m currently  testing the EP, it seems acceptable, But where this is going will be a outer white zone.  Obviously compared to a 21 ethos ,there is no comparison , lol!

I found it objectionable under dark skies as well as under light polluted skies. I didn't really notice any difference.

 

But it's worth stepping back for some perspective.

 

My 23 mm Luminos was trying the fly with the eagles, it was up against some very tough competition, the 21 mm Ethos, 22mm Panoptic, and the 31 mm Nagler.  These eyepieces are very well corrected in my fast scopes and are evenly illuminated across the field of view.. no EoFB..

 

How would I feel about the 23 mm Luminos if that's what I had?

 

I'd use it, that's for sure. And I'd probably like it better than the Erfle like derivatives that are the alternatives.

 

Jon

 


Edited by mark379, 24 July 2018 - 09:56 AM.

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#41 Jon Isaacs

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Posted 24 July 2018 - 10:10 AM

Jon,

 That actually answers my question  for the most part     Thank you !

 My main thought is to use this Ep for  out reach  in my clubs heavily light polluted main observing  area  with a 10 inch GSO F5 dob. 

 I guess my thought was would it make an object such as a nebula  disappear closer to the outer edges???

 I haven’t tested it yet under this condition but was wonderIng.  From what it sounds, it’s going to be better than the 25 mm erfle  currently being used by this telescope.  I was going to do the change out in September when our public telescope night begin at  Montclair  state university.  

 Under an orange zone where I’m currently  testing the EP, it seems acceptable, But where this is going will be a outer white zone.  Obviously compared to a 21 ethos ,there is no comparison , lol!

 

Mark:

 

An experienced observer might see a faint nebula disappear but for any nebula appropriate for outreach from a light polluted site, I should be fine. And much better than an Erfle.

 

I think what's so exasperating about this eyepiece is that it is that other than the EOFB, it's quite a decent eyepiece.

 

I did find that a 32-33mm field stop significantly reduced the EoFB.. 

 

Jon



#42 mark379

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Posted 24 July 2018 - 10:18 AM

Hi Jon,

 That’s great news... I had a feeling… Yes it may bother someone like me who's critical somewhat but you’re right overall it’s not a bad EP. 

 And for the price, I was hoping it would be an excellent out reach EP, And sounds like it is… Thank you my friend

Mark:

 

An experienced observer might see a faint nebula disappear but for any nebula appropriate for outreach from a light polluted site, I should be fine. And much better than an Erfle.

 

I think what's so exasperating about this eyepiece is that it is that other than the EOFB, it's quite a decent eyepiece.

 

I did find that a 32-33mm field stop significantly reduced the EoFB.. 

 

Jon


Edited by mark379, 24 July 2018 - 12:04 PM.

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#43 Starman1

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Posted 24 July 2018 - 07:10 PM

Very heavy, which I could live with if it was a good performer.  Impossible to see the edge of the field and not induce kidney bean.  Using it was a trial.  Mediocre edge quality, relative to even simple, uncorrected designs like Plossls.  Uneven brightness across the field.  The one bright spot was the centre was very sharp and contrasty.  Very good build-quality.  Far better than the crude black anodizing seen on some other eyepieces.  But I wish they'd spent some of the money on the optics and optical design. 

You don't mention the scope it's used in, but with 82° it's normal to have to roll the head over to look directly at the edge.

The edge will have a lot more problems because the field stop is so much larger.

At f/5, compared to a Plössl, there will be more astigmatism, field curvature, visible coma (if used in a newtonian), chromatic smear, chromatic aberration of the exit pupil, etc.

If the center was brighter than the edge, you also have vignetting.  If the edge was brighter than the center, that's likely in the eyepiece (EOFB, edge of field brightening).

But it's a very cheap eyepiece compared to what it attempts to copy:

TeleVue 31mm Nagler--$666.00

Celestron Luminos 31mm--$209.95


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#44 Usquebae

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Posted 24 July 2018 - 11:41 PM

I think the reputation of the 31 Luminos as "worst ever" is largely due to the peculiar niche it finds itself in.  Before decloaking it is bigger, heavier, and less comfortable (due to diameter of top housing) than its Meade & ES 30mm counterparts, with inferior images and - when it first came out - a higher price tag than a used Meade or super-sale ES.  Plus, the 31 Axiom that preceded the Luminos looked identical (except for the name) but was optically superior.  Even now that the price has dropped the 31 Luminos is in no-man's land, cheaper than the ES 30 but still pricey for any eyepiece in general. 

 

I'm guessing that anyone willing to spend $200 on an eyepiece will find a way to scrounge the extra 60-80 bucks for a used 35 Pan or a new 30 ES.  It would be well worth it in my opinion.  In a vacuum, though, I don't think it's an awful piece of glass.  If I was using a 30mm Erfle and someone gave me a 31 Luminos I would be quite happy with the upgrade.


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#45 mark379

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Posted 25 July 2018 - 03:53 PM

That very well may be the case...

#46 epee

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Posted 25 July 2018 - 04:04 PM

You don't mention the scope it's used in, but with 82° it's normal to have to roll the head over to look directly at the edge.

The edge will have a lot more problems because the field stop is so much larger.

At f/5, compared to a Plössl, there will be more astigmatism, field curvature, visible coma (if used in a newtonian), chromatic smear, chromatic aberration of the exit pupil, etc.

If the center was brighter than the edge, you also have vignetting.  If the edge was brighter than the center, that's likely in the eyepiece (EOFB, edge of field brightening).

But it's a very cheap eyepiece compared to what it attempts to copy:

TeleVue 31mm Nagler--$666.00

Celestron Luminos 31mm--$209.95

 

 

I think the reputation of the 31 Luminos as "worst ever" is largely due to the peculiar niche it finds itself in.  Before decloaking it is bigger, heavier, and less comfortable (due to diameter of top housing) than its Meade & ES 30mm counterparts, with inferior images and - when it first came out - a higher price tag than a used Meade or super-sale ES.  Plus, the 31 Axiom that preceded the Luminos looked identical (except for the name) but was optically superior.  Even now that the price has dropped the 31 Luminos is in no-man's land, cheaper than the ES 30 but still pricey for any eyepiece in general. 

 

I'm guessing that anyone willing to spend $200 on an eyepiece will find a way to scrounge the extra 60-80 bucks for a used 35 Pan or a new 30 ES.  It would be well worth it in my opinion.  In a vacuum, though, I don't think it's an awful piece of glass.  If I was using a 30mm Erfle and someone gave me a 31 Luminos I would be quite happy with the upgrade.

lol.gif  You guys sound like the Barbara Woodhouse of astronomy, "No bad Eyepieces"...

 

Which I tend to agree with. If the Luminos cost the same as a Nagler we might call it bad, but otherwise any eyepiece that lets you see more than you would otherwise isn't all bad.

 

Even so, from the talk around here, the Luminos never entered my mind regarding ownership.


Edited by epee, 25 July 2018 - 04:10 PM.


#47 Jon Isaacs

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Posted 25 July 2018 - 10:09 PM

Even so, from the talk around here, the Luminos never entered my mind regarding ownership.

 

 

A 23mm Luminos came my way via serendipity.  When one is accustomed to TeleVue eyepieces with a Paracorr, it's possible to become a bit on the picky side, spoiled.. 

 

I try to keep that in check.. Tonight, if the clouds don't roll in, I will be doing some observing with my Meade 310, an 80mm F/11 achromat and for eyepieces I will be using a set of Celestron Plossls, some made in Taiwan, some in China.  It's a nice combo and helps keep things in perspective.  

 

The 23mm Luminos, that darn EoFB.. :(

 

Jon



#48 jallbery

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Posted 26 July 2018 - 02:13 PM

I have the 15mm Luminos.   Most of my observing is at F/10 (or slower) and for $79 I paid,  I think it was a great value.   I didn't want to pay for a Nagler, the 14mm ES82 had checkered reviews, and the Luminos had a bit better eye relief (at least per the specs).   It does show a bit of EOFB, but under most conditions, not a distracting amount for me (YMMV).    I haven't used it enough at faster focal ratios to comment (and I don't have anything faster than F/6.1, anyway).


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#49 Usquebae

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Posted 27 July 2018 - 07:56 AM

The Luminos reputation is based on the performance of the 2" EPs (23, 31).  By most accounts the 1.25" Luminos oculars (7, 10, 15) are very good.  I personally have both Luminos and Axiom oculars in 15mm and 31mm focal lengths.  At 31mm the difference between the two is dramatic, but not so at 15mm.  The 15mm Luminos is a little softer at the edge than Axiom and has some EOFB but not gobs of it.  In both focal lengths the Luminos has significantly more eye relief.  Assuming the 7 and 10 are equal in quality to the 15mm I think the 1.25" Luminos EPs are quite good, and steal for the current prices.  In 2" format it's worth paying extra for ES or similar.


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#50 Exnihilo

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Posted 27 July 2018 - 09:32 AM

Very heavy, which I could live with if it was a good performer.  Impossible to see the edge of the field and not induce kidney bean.  Using it was a trial.  Mediocre edge quality, relative to even simple, uncorrected designs like Plossls.  Uneven brightness across the field.  The one bright spot was the centre was very sharp and contrasty.  Very good build-quality.  Far better than the crude black anodizing seen on some other eyepieces.  But I wish they'd spent some of the money on the optics and optical design.

I got the 23mm bundled with the 11" Edge. I don't use it; for its huge weight, its just not that great. Its OK, but why bother? I have a nice 30mm ES 82 deg, which is heavy as well, but actually worth the bother. I'm probably going to get rid of the Luminos.

Edited by Exnihilo, 27 July 2018 - 09:33 AM.



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