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28mm RKE junk now or still good?

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#1 azure1961p

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Posted 24 April 2013 - 07:16 AM

The 28mm RKE has been touted often as a great eyepiece but some say it used to be but now its plagued with quality control issues. Wouldnt something like a 32mm TV Plossl outdo it , albeit at less magnification, or is the 28mm RKE better still?

Thanks in advance!

Pete

#2 MRNUTTY

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Posted 24 April 2013 - 07:27 AM

I bought a set of RKE's and the Erfle, except the 28mm, new from Edmund Optics less than a year ago. There were no quality issues with the EP's I bought. my pair of 28's came from surplusshed. I don't believe if I had also purchased the 28's new there would have been any difference across the product line. The major glee factor comes from the floaty-effect of the 28, other than that, it's a competent EP in all respects.

I also bought the Edmund Scientific 8mm Plossl, which was of equal fit and finish.

#3 FirstSight

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Posted 24 April 2013 - 08:01 AM

The major glee factor comes from the floaty-effect of the 28, other than that, it's a competent EP in all respects.


I thought the "floaty" effect of the 28 RKE was considered a prime feature, rather than a bug, by that EPs aficionados. I myself find it a fun feature when I've looked through a fellow club member's 28 RKE, though not quite enough of a thrill to want to own one myself.

#4 hottr6

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Posted 24 April 2013 - 08:22 AM

+1. I consider the 28RKE a specialty EP, in the "fun" category. I've not found a serious application for them.

#5 Jeff B

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Posted 24 April 2013 - 09:18 AM

+1. I consider the 28RKE a specialty EP, in the "fun" category. I've not found a serious application for them.


Other than serious fun.

#6 DNTash

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Posted 24 April 2013 - 11:59 AM

The 28mm RKE has been touted often as a great eyepiece but some say it used to be but now its plagued with quality control issues. Wouldnt something like a 32mm TV Plossl outdo it , albeit at less magnification, or is the 28mm RKE better still?

Thanks in advance!

Pete


I'll be able to test those two in another day or two, clouds pending. Have the 32. The 28 is on it's way.

#7 Starman81

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Posted 24 April 2013 - 12:54 PM

+1. I consider the 28RKE a specialty EP, in the "fun" category. I've not found a serious application for them.


Other than serious fun.


:lol:

On a more serious note, I bought the RKE 28 brand new last year from Edmund Optics and there is no issue whatsoever with the quality. I think there were small number of SurplusShed units that had jagged field stops or other minor blemishes.

The TV 32 Plossl is perhaps the nicest ~30-32 Plossl out there (has anyone compared it to the Sterling Plossl 30mm?). The RKE 28 is what it is and it's main draw is the really cool floaty effect. I think most people look past the aberrations at the edge because the novelty of the effect trumps all other considerations. So if you want a more 'clinical view' the TV 32 might win out but the RKE is more novel.

#8 rdandrea

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Posted 24 April 2013 - 01:26 PM

I bought one of the 28mm RKEs from Surplus Shed and it's fine. No quality issues. I bought mine early--maybe by the end of the sale the bottom of the barrel wasn't so good.

Now on to the nitty-gritty. Between the RKE and my old Meade RG 28mm Ortho, two eyepieces of the same focal length and similar vintage, I prefer the Ortho, although the RKE is no slouch. Both have a little too much eye relief for me, however. Some see a "floaty" effect; I suppose that's true with careful eye placement. Mainly what I see, though, is blackouts and kidney-beaning like you get with any other "too much eye relief" eyepiece.

#9 John Kuraoka

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Posted 24 April 2013 - 01:37 PM

I have a fairly small eyepiece toolkit, and the 28mm RKE is one I bought out of sheer nostalgia. That said, I have found it to be a very useful eyepiece on open star clusters that need just a bit more magnification than my 35mm, and for giving a bit more context to other objects than my 25mm. It is superb Barlowed, giving me a useful and punchy 14mm. The floating-image effect is just an amusing ancillary feature, albeit one I never tire of.

#10 MRNUTTY

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Posted 24 April 2013 - 02:42 PM

I especially like the RKE 28 as a terrestrial piece in my C6-SCT since it's so easy to position your eye. My mom likes it too! For the same reason I got two (good ones) for my bino-viewer. They're good pieces i can use with the whole family.

#11 Messyone

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Posted 24 April 2013 - 06:51 PM

Just bought a pair of RKE 28's from Edmund Optics a couple of weeks back, no issues here with quality. Got them as a replacement for a pair of Vixen 30 NPL's but will keep both pairs. The RKE's are going to take a bit of getting used to, as has been said in other threads they are in a class all there own.
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#12 mak17

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Posted 25 April 2013 - 01:35 PM

Good compared to kellners and ramsden eyepieces. Not good if you're used to Naglers and ES 82s.

#13 fishuntime53

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Posted 25 April 2013 - 01:35 PM

My deep loyalty to Edmund (going back to the days I ground my 8" mirror in 1970) has kept me from expressing what I'm about to post. I returned to this hobby last year with a C11 and I'm loving it. I ordered the Edmund 28mm RKE and 32mm RKE/Erfle. Imagine my surprise to find that the filter threads on the 28mm were sub-standard, so I returned the eyepiece. In discussing the return with Edmund's Customer Service, they asked me why I would use filters with eyepieces. The 'technical' rep did not have the slightest familiarity with astronomy. Filters?
I moved on and bought an excellent 'older' 28mm from another source. I am truly saddened to see the decline in Edmund's expertise. Quality Control can only inspect what they are aware of, I suppose...

#14 Jon Isaacs

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Posted 25 April 2013 - 01:55 PM

Good compared to kellners and ramsden eyepieces. Not good if you're used to Naglers and ES 82s.


A while back I bought a Parks/Carton 60mm F/7 refractor, it was built in around 1990 and the one eyepiece that came with it was a 28mm Kellner that seems to have many of the same characteristics as the 28mm RKE, both had the same 23.3mm field stop and a image that seems to be as large as the barrel.

Vintage eyepieces, the one on the left...

It's not a 31mm Nagler but it doesn't weigh 2 lbs. What was nice about that eyepiece is that it while it had a rather narrow AFoV, the AFoV just seemed much larger, I call such views, "The Big Easy View."

Jon

#15 jrbarnett

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Posted 25 April 2013 - 02:56 PM

"Wouldnt something like a 32mm TV Plossl outdo it , albeit at less magnification, or is the 28mm RKE better still?"

Yes. The 32mm Televue Plossl is a better eyepiece than the 28mm RKE. I've had multiple iterations of each, and the Televue does a MUCH better job curbing haloing and reflections. What the Televue is missing, though, is the illusion that the image is floating atop the eye lens. IMO that's the main reason to own a 28mm RKE; a "parlor trick".

Regards,

Jim

#16 mak17

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Posted 25 April 2013 - 03:14 PM

That kellner looks nice. I wasn't trying to bash kellners just saying if you're used to wide fields that are well corrected you may be disappointed. I had a Meade DS90 with a .965 visual back and awful eyepieces as a first scope. The eyepieces had little pinholes with maybe a 40 degree field and maybe 10mm ER. I thought them great bc I had nothing to compare them to. When I got some 1.25 inch starter plossls i thought them amazing. After using nothing but Naglers and the like for the past year I now know better.

#17 bcuddihee

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Posted 25 April 2013 - 03:22 PM

"parlor trick" :foreheadslap:...I think that trivializes the effect and pleasure this eyepiece can give a viewer. After all one could say that a 100 degree ep is only a parlor trick, one trick pony etc.. ep as well. I would label this ep's visual nuance a a "more immersive view", perhaps even describe it as having the "majesty factor"...oops i think I've heard that one somewhere before. All in all I've never had quality issues with this ep and I've had several. It's a serious observers ep and delivers superb views.

#18 ckwastro

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Posted 25 April 2013 - 04:23 PM

The 28mm RKE has been touted often as a great eyepiece but some say it used to be but now its plagued with quality control issues.


I got a set for my binoviewer about 14 months ago direct from Edmunds........they are now my favorites for lunar & planetary observing in my Mewlon. No QC issues at all. In fact I grabbed the 21s and 15s as well and those were excellent as well. I'm looking to fill out the rest of the sets soon.

#19 Jon Isaacs

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Posted 25 April 2013 - 04:57 PM

That kellner looks nice. I wasn't trying to bash kellners just saying if you're used to wide fields that are well corrected you may be disappointed. I had a Meade DS90 with a .965 visual back and awful eyepieces as a first scope. The eyepieces had little pinholes with maybe a 40 degree field and maybe 10mm ER. I thought them great bc I had nothing to compare them to. When I got some 1.25 inch starter plossls i thought them amazing. After using nothing but Naglers and the like for the past year I now know better.


I have a set of Naglers plus a fair number of other eyepieces. I appreciate the Naglers, particularly in a fast Newtonian fitted with a Paracorr or fast refractor. I consider them my first string eyepieces for most uses.

But other eyepieces have their own virtues and I appreciate a good Kellner, particularly in a slower scope. The RKEs are quite far removed from those 0.965" eyepieces that you got with that Meade DS-90, they are reasonably well made, they have sufficient eye relief and the 28mm, while it doesn't have a Nagler like AFoV, it does have a field stop large enough to allow for 47 degree or so AFoV.

I think it would be a nice eyepiece in your Meade 310. At F/11, it will be quite sharp across the field of view and you won't be giving up too much field of view to a 32mm Plossl or 24mm WF.

Jon

#20 mak17

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Posted 25 April 2013 - 06:21 PM

Jon

What virtue do you appreciate most with the more primitive kellner design in a slow scope?

#21 ibase

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Posted 25 April 2013 - 07:19 PM

The 28mm RKE has been touted often as a great eyepiece but some say it used to be but now its plagued with quality control issues. Wouldnt something like a 32mm TV Plossl outdo it , albeit at less magnification, or is the 28mm RKE better still?

Thanks in advance!

Pete


Here are the RKE28mm & 32mm plossls:

Posted Image
L-R: RKE 28mm (Edmund Scientific version), TV 32mm, Baader Classic 32mm, Celestron 32mm

Sure the TV32 might edge out the RKE28 in edge correction, but the novelty floating projection effect that the RKE28 brings to the table can't be ignored and shouldn't be understated, it's the single attribute that had made legions fall in love with this gem of an EP and I'm not about to be without one.

Best,

#22 Starman81

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Posted 25 April 2013 - 08:19 PM

My deep loyalty to Edmund (going back to the days I ground my 8" mirror in 1970) has kept me from expressing what I'm about to post. I returned to this hobby last year with a C11 and I'm loving it. I ordered the Edmund 28mm RKE and 32mm RKE/Erfle. Imagine my surprise to find that the filter threads on the 28mm were sub-standard, so I returned the eyepiece. In discussing the return with Edmund's Customer Service, they asked me why I would use filters with eyepieces. The 'technical' rep did not have the slightest familiarity with astronomy. Filters?
I moved on and bought an excellent 'older' 28mm from another source. I am truly saddened to see the decline in Edmund's expertise. Quality Control can only inspect what they are aware of, I suppose...


Funny that you mention this, but just this past week I tried screwing on a moon filter onto the RKE to no avail. But nonetheless, I don't think there's any need to write off the RKE 28, no way, no how. It can strut its stuff and exist peacefully next to the TV 32 Plossl and even its cousin, the 28mm Edmund Plossl.

Attached Files



#23 Jon Isaacs

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Posted 26 April 2013 - 04:37 AM

Jon

What virtue do you appreciate most with the more primitive kellner design in a slow scope?


This particular Kellner is unique in that it provides this floating sensation. But in slow scopes, all that monkey motion that is going on in a Nagler to allow it to provide those sharp to the edge views in a fast scope is just not necessary. A small F/11 or F/13 refractor with Kellners or Erfle's they can provide some stunningly clean views.

Of course the majority of the time I am using a fast refractor or a fast Newtonian so I am using Nagler type eyepieces with a coma corrector if appropriate.

But there is something simple and pure viewing through a slow refractor or Newtonian, they barely bend the light at all, combined with simple eyepieces.

Jon

#24 dbledsoe

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Posted 26 April 2013 - 09:51 AM

The 28mm RKE has been touted often as a great eyepiece but some say it used to be but now its plagued with quality control issues. Wouldnt something like a 32mm TV Plossl outdo it , albeit at less magnification, or is the 28mm RKE better still?

Thanks in advance!

Pete


The 28 RKE is OK but nothing to get excited about. I've owned several of them over many years. Never could manage to hang onto one. They're a decent eyepiece but I'd take a 32 TV plossl any day over the RKE.

#25 ckwastro

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Posted 26 April 2013 - 09:58 AM

The 28 RKE is OK but nothing to get excited about. I've owned several of them over many years. Never could manage to hang onto one. They're a decent eyepiece but I'd take a 32 TV plossl any day over the RKE.


Interesting. My experience has been just the opposite. :grin: Love the 32 but sold it off. I'd never part with the 28 RKE.






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