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A really F-U-N eyepiece! My new 28mm RKE!

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#51 amicus sidera

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Posted 15 February 2012 - 06:13 PM

That $13.90 is shipping and handling, gentlemen... which means that in all likelihood Edmund is paying a living wage to it's mailroom personnel.

An excellent, well-designed, high-quality eyepiece, made domestically by an American company, and $6 or so is going to make or break the sale... I fail to understand this.

#52 Paraclete

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Posted 15 February 2012 - 06:17 PM

I've been looking for a used one for awhile now. It's amazing as if you don't bid on it within an hour you have zero chance of getting one.

Hey TMK! I was reading in your recent thread how you intended to condense your eyepiece collection. Now it seems like you want to expand it! :grin: I don't blame you!

#53 iceblaze

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Posted 15 February 2012 - 06:31 PM

That $13.90 is shipping and handling, gentlemen... which means that in all likelihood Edmund is paying a living wage to it's mailroom personnel.

An excellent, well-designed, high-quality eyepiece, made domestically by an American company, and $6 or so is going to make or break the sale... I fail to understand this.


I'm with you on that one. People have no problems dropping the big bucks on TV gear...

Why the big deal over an extra $6 for shipping for such an awesome eyepiece?

-James

#54 TMK

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Posted 15 February 2012 - 07:39 PM

I've been looking for a used one for awhile now. It's amazing as if you don't bid on it within an hour you have zero chance of getting one.

Hey TMK! I was reading in your recent thread how you intended to condense your eyepiece collection. Now it seems like you want to expand it! :grin: I don't blame you!


True. However I have the 15mm Edmund Scientific RKE and it's a wonderful eyepiece. The 28mm would make a welcome addition.

#55 astrodon

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Posted 15 February 2012 - 07:57 PM

I've noted the 28mm Meade RG ortho and 24mm Brandon to give similar 'fun' views. They're a bit more expensive than the RKE however. I bet the 32mm Meade 4000 smoothside does the same as well as the 32mm Brandon.

#56 Jaimo!

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Posted 15 February 2012 - 08:45 PM

You may be right... I have just received a 32mm Meade 4000 Smoothie this week, look at the photo below and how much glass & how little housing. Kids are getting ready for bed and the skies are clearing up, I think I have something to do...

Posted Image

Posted Image

Jaimo!

#57 BillP

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Posted 15 February 2012 - 08:58 PM

WoW...thanks for that link!!! I was so bumbed when I heard they closed the showroom. Everyone that went there loved it. There will never be a place that was soooo much fun! :bawling:

#58 amicus sidera

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Posted 15 February 2012 - 09:05 PM

I feel very much the same... :bawling:

We should be glad that we had the opportunity to experience it... there is nothing that compares to the Edmund Scientific showroom in this internet-driven, sanitized age...

#59 SATMAN

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Posted 15 February 2012 - 10:02 PM

You can still see that Japanese periscope that they had in the show room it's currently housed at the battleship New Jersey Museum , Edmund Scientific Donated it to the Museum after they closed the retail store in 2001.
I really like my RKE eyepieces since I bought my own set back that I gave away 28 years ago and unknowingly bought back on EBay see my post in the Classic Telescopes forum. :grin:

#60 Jaimo!

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Posted 15 February 2012 - 10:28 PM

I gave away 28 years ago and unknowingly bought back on EBay see my post in the Classic Telescopes forum.



That was a GREAT story!

Jaimo!

#61 Jaimo!

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Posted 15 February 2012 - 10:49 PM

I don't want to hijack the thread, but I took out my the 1 1/8"FL Edmunds eyepiece this evening with a 60mm f/16.7 Carton Refractor. Inspired by this post, I thought I'd would take it out and give it a spin against a 32mm Meade 4000 SS & a 32mm TV SS (NJ) Plössl. The only variable is which eyepiece "dissappeared" the most, my previous photos of the size of the housing have really NO bearing on what you actually see at the eyepiece... The Edmund's leaves very little of the eyepiece left to be seen when in use, followed by the 4000, then distantly followed by the TV. It was really no contest the Edmunds blew them away. When I was readying the Edmunds eyepiece to take out, I noticed a little dust on the field lens... One thing lead to another, so I took it apart. It is not an RKE or a symetrical, but more of a straight up Plössl, see below.

Posted Image

Enjoy,
Jaimo!

#62 Rick Woods

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Posted 16 February 2012 - 12:51 AM

Jaimo!,

That's a great avatar you have of Jimi's shadow on his shredded Marshalls. Do you know the story of that picture?

#63 Jaimo!

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Posted 16 February 2012 - 07:44 AM

I believe the show was at Harvard... but more information is always welcome.

Jaimo!

#64 BillB9430

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Posted 16 February 2012 - 09:25 AM

Jaimo!, thanks for posting the "exploded" photo showing the correct lens arrangement for the Edmund 1 1/8". It may help future owners of this classic eyepiece. I've purchased 4 used ones in the last 10 years to accompany gift spotting scopes I've made with surplus achromats and binocular prism cluster erectors. Three of them showed VERY poor images when they arrived. I compared them to my original, purchased in the 1960's (Edmund called it a Kellner!). One had the eye lens flipped, one had the field lens flipped, and the prize went to the third, which had BOTH lenses flipped from what they should have been. Once the lenses were oriented correctly, they all gave images as good as my original. Anyone taking one of these apart should know that the more strongly curved sides of the achromats go inward, as shown by your nice photo. Unless I was just VERY unlucky, this sort of thing must be common. At least the lenses are of slightly different diameter, so no one was able to "improve" the eyepiece while cleaning by reversing the lens positions!

I don't have an Edmund 28 RKE, but wonder how much the lenses in the currently offered RKE eyepiece differ from these old ones? - Bill

#65 Sarkikos

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Posted 16 February 2012 - 09:59 AM

Donald,

I've noted the 28mm Meade RG ortho and 24mm Brandon to give similar 'fun' views. They're a bit more expensive than the RKE however. I bet the 32mm Meade 4000 smoothside does the same as well as the 32mm Brandon.


I have a 32mm Brandon. I haven't noticed if it gives a "lost in space" view like the 28mm RKE. I'll have to check that out next time I use the Brandon.

But I do have a weird eyepiece that gives a view similar to my 28mm RKE, so that the eyepiece appears to disappear when you look through it. That's my Rini "Modified Plossl/RKE" 45mm. It's a 1.25" eyepiece with 36mm eye relief and about 36mm AFOV! I think the barrel is made from Delrin. It has a long, built-in eye cup that is actually an extension of the barrel. The field stop is the rim of the barrel, but that virtually disappears when you look through the eyepiece at objects in the night sky.

This bizarre eyepiece actually gives nice, sharp contrasty views, but the narrow FOV pretty much defeats the purpose of a low power eyepiece. It gives a very interesting view of the full disk of the Moon through my 90mm Mak.

The only eyepieces I own which have narrower FOVs are a Russian Kellner 43mm with 34mm AFOV and my Huygens at about 30mm AFOV.

Mike

#66 BillP

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Posted 16 February 2012 - 10:13 AM

I really like my RKE eyepieces since I bought my own set back that I gave away 28 years ago and unknowingly bought back on EBay see my post in the Classic Telescopes forum. :grin:


Pictures please :grin: ...or a link to the exact post you are talking about.

#67 Paraclete

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Posted 16 February 2012 - 03:58 PM

Here it is: (This was an awesome story. One in a million)
Suprise set of 1970's vintage RKE's with a Twist.

#68 Lane

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Posted 16 February 2012 - 05:10 PM

So now we have the "floating" image and the "lost in space" image. Does anyone have a "firefly serenity" image?

#69 Starman1

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Posted 16 February 2012 - 09:33 PM

I owned both of these eyepieces (the 28 (aka 28.7)mm RKE and the 1-1/8" Plossl) several years ago.
I remembered liking them a lot, so I reacquired them.
I remembered the 1-1/8" Plossl as having an image that just sort of floated in front of the eyepiece (it was $12.95 the first time I bought one!).
But, alas,
1) They have tremendous astigmatism at the edge of the field of view in anything shorter than f/8. And they weren't very good in the 8" SCT at f/10, either.
2) Both had serious lateral chromatic distortion.
3) And I won't go into other aberrations that indicated a lack of correction.

The scopes I owned when I owned these the first time were f/10.5, f/15, and f/10.

The scopes I owned when acquiring these the second time were f/5, f/5.6, and f/6.

In contrast, the 35mm Parks Gold and 32mm Meade Series 4000 Super Plossl (5-element, Japan) had the same "no-rim" impression but had far better control of edge of field distortions.

So, caveat emptor. Long focal ratios recommended.

#70 amicus sidera

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Posted 16 February 2012 - 10:23 PM

I owned both of these eyepieces (the 28 (aka 28.7)mm RKE and the 1-1/8" Plossl) several years ago.
I remembered liking them a lot, so I reacquired them.
I remembered the 1-1/8" Plossl as having an image that just sort of floated in front of the eyepiece (it was $12.95 the first time I bought one!).
But, alas,
1) They have tremendous astigmatism at the edge of the field of view in anything shorter than f/8. And they weren't very good in the 8" SCT at f/10, either.
2) Both had serious lateral chromatic distortion.
3) And I won't go into other aberrations that indicated a lack of correction.

The scopes I owned when I owned these the first time were f/10.5, f/15, and f/10.

The scopes I owned when acquiring these the second time were f/5, f/5.6, and f/6.

In contrast, the 35mm Parks Gold and 32mm Meade Series 4000 Super Plossl (5-element, Japan) had the same "no-rim" impression but had far better control of edge of field distortions.

So, caveat emptor. Long focal ratios recommended.


Using the 28mm RKE in instruments of focal length f5 and greater, I do not find the degree of astigmatism to be objectionable in the least, neither do I consider the distortions to be as severe as you seem to have experienced.

These eyepieces were not designed specifically for ultra-fast focal ratios under f5, but for what Edmund was offering at the time - telescopes the majority of which had focal ratios ranging from f5 to f10. That said, I use the 28mm RKE on my Astroscan at f4 (its supplied eyepiece, incidentally), and I still find the views to be splendid.

I have not viewed through the Parks 35mm, but in my opinion the Meade 32mm does not exhibit the same "floating" effect as the 28mm RKE... similar in some respects, but not identical.

#71 tcmzodiac

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Posted 16 February 2012 - 10:58 PM

Jaimo!, thanks for posting the "exploded" photo showing the correct lens arrangement for the Edmund 1 1/8". It may help future owners of this classic eyepiece. I've purchased 4 used ones in the last 10 years to accompany gift spotting scopes I've made with surplus achromats and binocular prism cluster erectors. Three of them showed VERY poor images when they arrived. I compared them to my original, purchased in the 1960's (Edmund called it a Kellner!). One had the eye lens flipped, one had the field lens flipped, and the prize went to the third, which had BOTH lenses flipped from what they should have been. Once the lenses were oriented correctly, they all gave images as good as my original. Anyone taking one of these apart should know that the more strongly curved sides of the achromats go inward, as shown by your nice photo. Unless I was just VERY unlucky, this sort of thing must be common. At least the lenses are of slightly different diameter, so no one was able to "improve" the eyepiece while cleaning by reversing the lens positions!

I don't have an Edmund 28 RKE, but wonder how much the lenses in the currently offered RKE eyepiece differ from these old ones? - Bill


Bill....my late 60's Edmund 4 1/4" newt came equipped with an "Edmond" Kellner....28mm(??) Any insight on that?

#72 BillB9430

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Posted 17 February 2012 - 01:31 AM

Terry, that's likely the same eyepiece. 1 1/8" = 28.575 mm. I don't know about the alternate spelling of Edmund. I have long thought that the early ones were likely sold as 1 1/8"FL Kellners, while later the same eyepiece was labeled 28 mm Kellner. I found some old Edmund and American Science Center catalogs, and now I'm not so sure. My oldest Edmund catalog is #613. In this one, the Stock No 5223 Kellner eyepiece is listed as 28 mm focal length, selling for $7.95. I cannot find a date in that catalog. However, the 1962 American Science Center catalog (basically the Edmund Catalog, but based in Chicago) also lists the No. 5223 Kellner eyepiece as 28 mm, selling for $7.95. I know I bought mine a few years after 1962, but it is stamped 1 1/8" FL. They must have sold a boatload of them at these prices, but this was considerable "paper route" money for me back then. - Bill

#73 BillP

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Posted 17 February 2012 - 08:15 AM

I don't have an Edmund 28 RKE, but wonder how much the lenses in the currently offered RKE eyepiece differ from these old ones? - Bill


The current 28 RKE is just that, a reversed Keller, 3 elements in 2 groups. So nothing at all akin to the 1-1/8".

Don - FWIW I find these eyepieces a lot of fun to use in all my scopes, fast and slow, and more critical productive observing as well. And yes, like any simple design they will have off-axis issues in faster scopes, but given the low magnification they produce in most, I find it more than acceptable. Besides, it's attributes IMO far outweigh its weaknesses.

Jaimo! - Thanks for the "exposed" version :) I've taken mine apart a number of times but never took note of the 2 groups not being symmetrical. OMG...perhaps a truer Plossl design here :shocked:

#74 Vondragonnoggin

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Posted 17 February 2012 - 08:58 AM

I haven't noticed any color fringing or readily apparent off axis, edge of field astigmatism. I had them in my BT last night at F/6.2 and was barely able to fit all three belt stars of Orion in the same view. The outer stars were at the very edge and still pinpoints. I use this piece in a 5x Barlow for planetary in my refractor too. Lunar views too. I do have some eyepieces where theses aberrations show up, but the RKE does not stick out for being bad at anything except needing good eye placement. As an included eyepiece for the astroscan, the low power with such fast optics makes the coma of the astroscan stick out pretty good, but it really still is a pleasing view. The floaty effect kind of lessens noticing the seagull stars as much on the edges.

All in my own experience with my two older and newer RKE pair.

I also have a Parks 35mm. It doesn't produce the floating effect, but has so many other great qualities, I feel everyone should at least look through one to admire the view.

:cool:

#75 jrbarnett

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Posted 17 February 2012 - 10:56 AM

Another one that comes close to the 28mm RKE in terms of the "floating affect" is the 28mm Meade RG Ortho. You don't see many of them around though...


Yep, the 28mm Meade RG Ortho and 20mm RG WA both produce this effect. The 48mm Brandon and 50mm Parks Plossl, also, produce this effect. Vondragonnoggin nailed it with his description, too.

Regards,

Jim


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