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The red grippy band is new, the older ones were plain metal. I assume the optical design is unchanged

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what can be expected of this eyepiece compared to those in above pics?

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so they are now about 30 years old. They all have a red grippy band. (8,15 & 28mm.)

dan

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That all? They're youngsters! If you're thinking of selling them, don't forget to put 'Factory fresh' in the ad

Didn't realise the red n black look went back that far, mine was bought 2nd hand so I've no idea how old it actually is apart from 'old'.

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Currently have several 27mm - 36mm's:


L-R: Panoptic 27mm, UWA-80 30mm, Proxima 31mm, Seibert 36mm Observatory Series (together with TMB Paragon 40, GSO 42mm)


Meade SWA 28 & 34mm Series 5000

Placed an ad at A-mart for an RKE 28mm and found one - it's on the way (eyepiece #71 in the stable); what can be expected of this eyepiece compared to those in above pics? So excited to receive and try out the new EP. Thanks.

Best,

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The red grippy band is new, the older ones were plain metal. I assume the optical design is unchanged

Have a look here for a biiiiig thread about the joys of the RKE 28.

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I purchased my RKEs the early 80's so they are now about 30 years old. They all have a red grippy band. (8,15 & 28mm.)

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what can be expected of this eyepiece compared to those in above pics?

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Hernando, you need to compare these to your stable unbiased, and then report your findings... If someone tells you what to expect you will have a bias and may subconsciously agree. But if you go in unbiased what you learn and the opinions you gain are MUCH more valuable. I'd love to hear your opinions after a few evening of comparisons.

By the way, nice looking eyepieces.

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Thanks Jaimo! If possible, will bat for an unbiased comparison and post opinions when I've gotten hold of the EP.

Best,

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A unique experience compared to all of those. Smaller FOV, more critical eye placement, but definitely a unique view.

Quite a bit lighter weight than all of those as well.

Keep an open mind. The view will grow on you. Remember to back your eye off a ways if you get blackouts. Loooong eye relief.

I think the older with no grippy band is the 1 1/8 marking type.

I have the 28mm SWA which is a great eyepiece, but I often grab the RKE because it offers up quite a different view. In my opinion, it shows brighter images. Can't say that would be for everyone though. This is for either older or newer with grippy band. They are identical when taken apart, and I can't tell the difference.

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Your quite lucky Hernando. I've been keeping an eye out for the 28mm for quite some time on the used market and it's a tough one to land.

I have the red banded 15mm and I really love it. I'm surprised it doesn't get more fanfare. Good luck and again congrats on finding the 28mm.

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You will really enjoy the RKE's they are a well kept secret vintage eyepieces , I originally bought mine in 1978 they as far as I know have always had the red grip band , they work extremely well in longer focal length Telescopes. See my post in the classic telescopes forum " suprise set of RKE eyepieces"

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What's under the red band? Mine's just got a ring of grooves, it came as is with no band, perhaps it lost it?

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Couldn't tell as I haven't received the EP yet, but here's another pic from the seller (posted with permission):



Can't seem to find the ring of grooves in there. I hope nothing got lost or anything, thanks.

Best,

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I have the 28mm SWA which is a great eyepiece, but I often grab the RKE because it offers up quite a different view. In my opinion, it shows brighter images. Can't say that would be for everyone though. This is for either older or newer with grippy band. They are identical when taken apart, and I can't tell the difference.

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I have the 28mm SWA which is a great eyepiece, but I often grab the RKE because it offers up quite a different view. In my opinion, it shows brighter images. Can't say that would be for everyone though. This is for either older or newer with grippy band. They are identical when taken apart, and I can't tell the difference.

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This says SHOOT OUT all over it !!!

Cheers,

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Two things -

I'm not worthy and my pair is shipping to Canada next week to assist in some testing of another instrument.

I will have to resort to using the most excellent Meade 28 SWA exclusively for a little bit.

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I have the 28mm SWA which is a great eyepiece, but I often grab the RKE because it offers up quite a different view. In my opinion, it shows brighter images. Can't say that would be for everyone though. This is for either older or newer with grippy band. They are identical when taken apart, and I can't tell the difference.

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This says SHOOT OUT all over it !!!

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Looking forward to this!

Best,

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..the most excellent Meade 28 SWA..

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You're welcome Hernando

There's another thread worth trying to find in the eyepieces forum, "Favorite eyepieces" or something similar. Lots of mentions of the usual multi-$$$$$ high-end suspects, as you'd expect, but also a lot of mentions of the RKE 28, including from the high-end-owners.

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Thanks again Bob; wow, for something that I paid $42 for, it sure is a comforting thought that the RKE 28mm is among the pantheon of "Favorite eyepieces," walking tall with expensive hi-end EP's!

Best,

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Oh, you got a goodie and no doubt just don't expect a flat-field view, and you'll be fine, the RKE will distort at the edges, but you won't care

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Thanks, nicely put, I'm liking it already!

Best,

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I bought an Edmund 1 1/8" "Kellner" new nearly 50 years ago (still have and use it) and now just received a new 28 mm RKE.

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Another RKE I've seen but never owned is the 8mm Wide angle.

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Hi Hernando,

I can guarantee yours is not in the most recent housing. Yours reads Edmund Scientific. That brand ceased to exist in the 70's.

I have purchased a set of RKE's from Edmund optics. They came in three different barrel types. I have only kept the 28mm, which was the only one in a modern barrel. By the way, the 8mm arrived chipped.

15, 12 and 8mm models have too tight eye relief to have any use.

28.7mm model(28mm) feels special, due to the famous "eyepiece vanish effect".

I have read on you blog - nice blog by the way - it exhibited field curvature on your f5.9 scope. Do you have a higher focal ratio scope to try it on?

I have a f8 scope and the field curvature problem is not that prominent.

I will post pictures of mine as soon as I can.

I am tempted to machine to field stop to meet the barrel inner diameter. this will yield about 60º of AFOV.

ATTENTION: Do not unscrew the barrel with the field lens facing down. The optics will fall on the floor.

Congratulations on your purchase. It will be a future classic

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I bought an Edmund 1 1/8" "Kellner" new nearly 50 years ago (still have and use it) and now just received a new 28 mm RKE. Both are nice eyepieces, but I do like the defined field stop in the RKE instead than the rather reflective inner barrel visible in the old "Kellner". I will use the RKE without the rubber eye guard that was sent in the package, but offer this caution for those who try that guard. In applying the rubber eye guard to the eyepiece, I carelessly allowed the forward edge to brush the field lens. Big mistake! Apparently there is some material on the rubber that transfers to the glass, making a mark. It was NOT removable with my standard lens cleaner! Fortunately, a little acetone on a Q-tip removed the mark completely. If you don't have acetone handy, be very careful. -Bill

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Hernando, keep using the RKE. It will grow on you the more you use it. The eye placement issue becomes a non-issue very fast. I thought it was a cool eyepiece when I first used mine, but after some time using it, I moved it to the "must keep" category and it has become one of my most used eyepieces. Sometimes I just go out and view with a 2x barlow, a 5x Powermate, and the 28mm RKE. Three magnifications all with that floaty effect and barlowing it gets rid of any edge artifacts.

I am waiting for Explore Scientiics barlows to come out. I think they are reintroducing the Meade 5000 series teleXtenders in 1.25". I have a 2", 2x TeleXtender, but really want the 1.25" 2x, and 3x teleXtender telecentrics. With a 2x, 3x, and 5x Telecentric design, I'll get the 28mm RKE in 4 magnifications and no added eye relief. Hmmmm, maybe a 2.5 Powermate is in order to make the 28 RKE an eyepiece case application.



I also saw you noticed the 45 degree AFOV appears wider in use. I think it does too.

Now that I'm thinking about this, all those telecentrics plus my 28 RKE and 35mm Parks Gold would be just about everything I'd need to be happy with my views and make the rest of my eyepieces collect dust.

I think I just created my list for purchases....

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I bought an Edmund 1 1/8" "Kellner" new nearly 50 years ago (still have and use it) and now just received a new 28 mm RKE.

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If you take the 1-1/8" apart, you will find it is not a Kellner but an asymetrical Plossl design, perhaps a Clave-style Plossl. So it is 4 elements in 2 groups.

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Thanks for chiming in Bill. Been curious for sometime already about the Clave plossl, hmmm..

Best,

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I've got the 28mm RKE from 1981 and like it a lot. It came with a Edmund 8 f5 #4001 ota.
I usually use the eyecup.
Some 1980's Edmunds ads reads 60* but 45 degree is more like it unless some where 60*
Another RKE I've seen but never owned is the 8mm Wide angle.
Anyone have info of these and where there others.
Any ways, good purchase.
Clear Skies
Sam

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>I have read on you blog - nice blog by the way - it exhibited >field curvature on your f5.9 scope. Do you have a higher >focal ratio scope to try it on?

Yup - on my rich field there is noticeable softness towards the edge but on my 100mm F13 Carton...
Sublime just about describes it.

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If you take the 1-1/8" apart, you will find it is not a Kellner but an asymetrical Plossl design, perhaps a Clave-style Plossl. So it is 4 elements in 2 groups.

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Sorry, for the late response... I've been away.

1 1/8" Edmunds "Pre-RKE":


Jaimo!

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Thanks for posting your exploded view! Yes, very obvious difference is that the lens edges are not blackened in your RKE28mm version. Not sure if the optical performance is identical.

Best,

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Thanks for posting your exploded view! Yes, very obvious difference is that the lens edges are not blackened in your RKE28mm version. Not sure if the optical performance is identical.

Best,

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The RKE is a 3 element 2 group eyepiece. It also has a field stop in the barrel.

The 1-1/8" is a 4 element 2 group eyepiece. It has no field stop and uses the barrel as the field stop whcich gives it about 10 degrees more AFOV than the RKE.

Performance-wise both give the "floating" effect they are famous for. I do notice a subtly better performance on-axis for planetary with the 1-1/8" over the RKE, giving a little more clarity and apparent contrast, which is why I prefer those over the RKE for bino with a 3.5x for planetary. It is subtle, but there to my eye.

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Thanks much for explaining the differences and for sharing your experience with the vintage and more recent RKE28's. Will be looking out for the 1-1/8" version to add to the stable, but doubt if there are owners willing to part with them at this time.

Best,

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For the handful of people on CN who do not have an Edmund 28mm RKE yet, Surplus Shed has them (unused) in their "New This Week" category now (April 15) for $35! If you put "Please apply my discount" in the Comments box, you'll get 15% off THAT for just $29.75!

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rdandrea, Surplus Shed usually applies the discount when they charge your card just before shipping, so you may get that discount after all. The extra discount deal is good for orders through tomorrow only, however.

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For the handful of people on CN who do not have an Edmund 28mm RKE yet, Surplus Shed has them (unused) in their "New This Week" category now (April 15) for $35! If you put "Please apply my discount" in the Comments box, you'll get 15% off THAT for just $29.75! If you are a VIP member of Surplus Shed, there's another 10% off and free shipping, too (otherwise shipping is $5). Seems like a no-brainer if you don't have one of these eyepieces yet.

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Thanks for the "heads up"!


I've had a single Edmund 28mm RKE for years. It's always been in my eyepiece case and is one of my favorite galaxy-hopping EPs.

Just bought another pair of these for future bino-viewing. I'll keep my fingers crossed that they are a matched set.


Cheers!
Blake

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Just bought another pair of these for future bino-viewing. I'll keep my fingers crossed that they are a matched set.

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Congrats on the in-coming RKE 28mm pair for the bino-v. In all likelihood they'd probably be a matched set, coming as they are from maybe the same batch. At one time I even took a leap of faith and blindly bought another UO 12.5mm hoping that it would work on my binoviewer together with the one I already had:



The two VT's shown above were obviously from different batches/versions (the one on the left has the infamous undercut) and yet they worked wonderfully when used as a pair!

Best,

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I bought 2...

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I'm RKE crazy.

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Hahaha LOL
One can never have too many RKE28's!

Best,

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If you take the 1-1/8" apart, you will find it is not a Kellner but an asymetrical Plossl design, perhaps a Clave-style Plossl. So it is 4 elements in 2 groups.

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Sorry, for the late response... I've been away.

1 1/8" Edmunds "Pre-RKE":


Jaimo!

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Hmph... Sorry I've been away from CN a while...

I had an original set of RKE's - full set - 8, 12, 15, 21 and 28mm when they first were made in the early 1980's and used them with a variety of scopes:

- 4" f/10 Meade SCT,
- 8" Celestron 8,
- 6" f/5 Newtonian,
- 12" f/3.7 Newtonian.

Originally Edmund designed and sold the RKE's for the little Astroscan telescope, a 4.25" f/4.2 Newtonian on a ball mount. There appeared to have been some attempt to optimise the RKE design to match the optical characteristics of this scope and it is quite noticeable that they perform very well for such a simple eyepiece when used in a Newtonian around f/4 to f/5.

Other budget eyepieces of that era were primarily orthos, Kellners, Erfles or Konigs and the RKE stood out against that crop for being admirably sharp in a Newtonian, with the apparent field of view being fairly typical for that era (we can leave Naglers out of this as they cost 10X as much at that time).

Characteristics:

The good:

- Excellent transparency and little colour thanks to the relatively short glass path and low number of glass-air surfaces compared to modern ultra wide designs, and they're coated.

The 28mm and 21mm had nice eye relief and fine for modest wide field views. The 15mm was ok but I didn't have much use for it. While the 8 and 12mm were OK for planetary, they were painful to use (impossibly short eye relief) and had a LOT of pincushion distortion.

The bad:

- Pincushion distortion - lots of it, and bad enough to distort jupiter or saturn quite badly when off-axis in the 8mm.

- Very limited field of view by modern standards.

- You must take care not to scratch the eye lens of the 28mm, it is convex and protrudes beyond the barrel - it is a shame Edmund didn't extend the barrel a few mm to protect it.

A few years ago I donated the RKE set to a worthy cause, and replaced it with a set Vixen LV's which are a whole lot better thanks to the consistent eye relief and better glass, with no regrets.

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I have to hold on to it for a while... I need to compare it to my new RKE when it arrives.

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Iluxo wrote:

(snip)Originally Edmund designed and sold the RKE's for the little Astroscan telescope, a 4.25" f/4.2 Newtonian on a ball mount. There appeared to have been some attempt to optimise the RKE design to match the optical characteristics of this scope and it is quite noticeable that they perform very well for such a simple eyepiece when used in a Newtonian around f/4 to f/5.

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(snip)While the 8 and 12mm were OK for planetary, they were painful to use (impossibly short eye relief) and had a LOT of pincushion distortion.

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(snip)You must take care not to scratch the eye lens of the 28mm, it is convex and protrudes beyond the barrel - it is a shame Edmund didn't extend the barrel a few mm to protect it.

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Perhaps this was a very early example? I've never owned an RKE with this issue... my early 1980's, early 1990's and 2012 versions of the 28mm RKE all have their eyelens recessed below the level of the surrounding barrel.

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My RKE doesn't quite protrude but it's very close:

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Good comments! If I may respond:

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Iluxo wrote:

(snip)Originally Edmund designed and sold the RKE's for the little Astroscan telescope, a 4.25" f/4.2 Newtonian on a ball mount. There appeared to have been some attempt to optimise the RKE design to match the optical characteristics of this scope and it is quite noticeable that they perform very well for such a simple eyepiece when used in a Newtonian around f/4 to f/5.

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The Astroscan came out in late 1976, and I believe was originally was equipped with the 1-1/8" focal length RKE precursor. The RKE line proper was introduced a bit later, around 1978 or so, coinciding with Edmund's introduction of their new 8" f/5 and 6" f/6 fork-mounted reflectors. I agree that the line performs very well indeed with relatively fast 'scopes such as the Astroscan and these two reflectors, and I'm sure that was the intention.

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(snip)While the 8 and 12mm were OK for planetary, they were painful to use (impossibly short eye relief) and had a LOT of pincushion distortion.

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Indeed, the eye relief is almost intolerable on the 8mm and only slightly better with the 12mm - certainly not an eyepiece for eyeglasses wearers! Much of this is due to the machined housing that rises much too far above the eyelens. Back in the 1980's I threw an 8mm I had on the lathe and turned down the housing considerably, to just a few millimeters above the eyelens... the eye relief was still a bit tight, but nowhere near as bad as it had been.

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(snip)You must take care not to scratch the eye lens of the 28mm, it is convex and protrudes beyond the barrel - it is a shame Edmund didn't extend the barrel a few mm to protect it.

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Perhaps this was a very early example? I've never owned an RKE with this issue... my early 1980's, early 1990's and 2012 versions of the 28mm RKE all have their eyelens recessed below the level of the surrounding barrel.

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Thanks for the additional info on the RKE's! I've been eying a red Astroscan can if one comes around at a good price.

Best,

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My RKE doesn't quite protrude but it's very close

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Same thing with my RKE28 "Edmund Scientific" where the surface of the eye lens is recessed just a teeny bit below the EP's top rim as shown below:



P.S. The news about the availability of the RKE28mm at Surplus Shed for only $35 had spread to 2 other threads in the forum; they will surely be cleaned off the shelf in no time now.

Best,

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Well... despite all the hype over you guys (re)discovering the RKE 28mm, I should add there is an EVEN BETTER eyepiece - if you have the scope to match it.

It is the Vixen LV50mm, its a 2" massive piece of glass weighing a pound, and you MUST have at least an 8" f/10 to f/15 scope to do justice with this beastie - it is NOT suited to shorter/smaller scopes as they cannot fill the field of view - this baby is basically TWICE THE SIZE of the RKE28mm.

To give you some idea, the eye lens on this beastie is bigger than most finders !

Like the RKE28mm, the LV50 provides a stupendous amount of eye relief, maybe 30mm, and you will get the 'stars floating in front of my nose' effect, and they are tack sharp edge to edge like diamonds on velvet.

Those with faster/smaller scopes need not apply.

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Manuel, the red ring is indeed recessed into a smoothly-machined cutout in the barrel, on models from both Edmund Scientific and Edmund Optics.

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Yes it is embedded, but on my Edmund Scientific, I am unable pry open the red rubber grip to see what's under as the rubber is securely attached thereon as shown below:

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Note the size of the LV50 - its bigger than the Masayuma 45 and far heavier - it is a LOT of glass.

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Wow Chuck, thanks, that oldest RKE (silver) is a beauty, I like it too, I want one!

P.S. I noticed your link has reference to "Jethro Tull" of the Aqualung fame, great band!

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Hey ibase:

The old silver eyepiece used to be black anodized, but after nearly 45 years of constant use, the anodizing has worn-off, leaving only machining marks and a trace of anodizing in the "low" spots. Still works great.

There is no engraving at all on that eyepiece. Never has been. I think that back then, Norm Edmund had barrels machined for whatever lenses he had a large stock of. 28mm (or thereabouts) is a great focal length for scopes of 48" and longer focal length (6" f/8 Newts, by far the most popular scope in the '60's) so I think that just might have been a factor in Edmund's decision to go forward with a mass-produced 28mm eyepiece using OEM optics instead of strictly US government surplus. But who knows for sure?

I've been a fan of Jethro Tull since about 1969, and have been to many, many concerts. Still have an original "Thick As A Brick" T-shirt, and have my tickets for the Thick as a Brick Volume 2 concert, due to be in my neck of the woods this fall. Ian Anderson has written a sequel to the original TAAB and I can't wait.

Rock on!

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Manuel, the red ring is indeed recessed into a smoothly-machined cutout in the barrel, on models from both Edmund Scientific and Edmund Optics.

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Yes it is embedded, but on my Edmund Scientific, I am unable pry open the red rubber grip to see what's under as the rubber is securely attached thereon as shown below:

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Thanks for that info. It sure seems like mine is a pretty old one then - it's in the same style body as the "1 1/8". I wonder if the Astroscan it was included with is as old...

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Manuel, I think you're on to something, I borrowed your RKE image (hope you don't mind) to show it side-by-side in my response to Chuck at the next post below, thanks.

Best,

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Wow Chuck, thanks, that oldest RKE (silver) is a beauty, I like it too, I want one!

P.S. I noticed your link has reference to "Jethro Tull" of the Aqualung fame, great band!

Best,

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Hey ibase:

The old silver eyepiece used to be black anodized, but after nearly 45 years of constant use, the anodizing has worn-off, leaving only machining marks and a trace of anodizing in the "low" spots. Still works great.

There is no engraving at all on that eyepiece. Never has been. I think that back then, Norm Edmund had barrels machined for whatever lenses he had a large stock of. 28mm (or thereabouts) is a great focal length for scopes of 48" and longer focal length (6" f/8 Newts, by far the most popular scope in the '60's) so I think that just might have been a factor in Edmund's decision to go forward with a mass-produced 28mm eyepiece using OEM optics instead of strictly US government surplus. But who knows for sure?

I've been a fan of Jethro Tull since about 1969, and have been to many, many concerts. Still have an original "Thick As A Brick" T-shirt, and have my tickets for the Thick as a Brick Volume 2 concert, due to be in my neck of the woods this fall. Ian Anderson has written a sequel to the original TAAB and I can't wait.

Rock on!

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Nearly 45 years of constant use of the RKE28 - that's amazing! I've been into this for only 4 years (started in 2008), and that means I have to wait around 4 more decades for my RKE to become the silver beauty like yours!

Below is a pic of your silver RKE (I hope you don't mind my borrowing it and doing some processing/re-scaling) vis-a-vis that of Mmclure's all-black RKE28 posted earlier:



They look very similar in shape, form & grip ring style, and since there were no engravings ever on the silver one as you said, then it must pre-date that of Mmclure's, and probably also that of Jaimo!'s (1-1/8"). That puts your silver RKE as the oldest one here to-date! (I wonder if there is anybody who has an even older RKE28 than this silver.) Very interesting background story too about the early days and origins of the RKE28, thanks!

P.S. How I wish I can attend the concert of Jethro Tull, but I'm at the opposite side half-way around the globe! Enjoy!

Best,

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