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

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#1 Paraclete

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Posted 11 February 2012 - 09:36 PM

I am stunned by my new 28mm RKE. It is without a doubt, the most F-U-N eyepiece I have ever used!

First light was an awakening. It instantly became abundantly clear to me that you don't have to spend a lot of money to have a lot of fun in this hobby.

The 28mm RKE for me is major-league eyepiece for a relatively low price. Word is slowly getting around here on CN about this eyepiece's mystical ability to project a "floating" image. My experience was just as others reported. Once you've got your head positioned in just the right spot, the housing for they eyepiece just completely disappears. All that's left is this floating image that is indescribable.

It was as striking as it was bewildering. The effect is like nothing I have ever imagined in an eyepiece.

I always thought my other eyepieces (like my Brandons and my Ultrascopics) gave this floating effect, but the 28mm RKE is at a whole other level.

I used all the eyepieces in the attached picture for first light, and the 28mm RKE was by far the most fun eyepiece I used. I didn't want to stop using it.

Funny how little recognition this terrific eyepiece gets. I bet if it sold for 10x as much and had different color lettering, it would be heralded as the second coming!

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#2 BillP

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Posted 11 February 2012 - 10:11 PM

Yup...me too....love my 28 RKE :grin:

#3 Lane

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Posted 11 February 2012 - 10:18 PM

Better than the 25mm UO VT Ortho?

#4 BillP

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Posted 11 February 2012 - 10:28 PM

The 28 RKE is really in a class all its own. Some come close at replicating how it behaves, but none succeed fully IMO. They are an absolute hoot to bino with Barlow also...especially if you are a sketcher. I use an effective 3.5x Barlow with mine in Binos for about an effective 8mm focal length. The ER extends fairly far with this setup, so far that I can keep my head in one spot and simply shift my eyes to view through the Bino-ed RKEs or down to the sketch pad. So makes sketching through the scope like sketching with no scope at all since can just glance up at the target, then glance down at the sketch pad. :D

#5 amicus sidera

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Posted 11 February 2012 - 10:29 PM

Another convert to the realm of the 28mm RKE... :grin:

They are a great eyepiece, indeed. I have to say that I do not care for the rest of the RKE line as much as the 28mm, as I wear eyeglasses and, save for the 21mm, the eye relief is too short to suit me... even so, they are remarkably sharp, and excellent eyepieces overall, especially at their price point.

The "floating" effect you describe is a bit magical, isn't it? I have never seen it's like in another eyepiece. The effect is not so pronounced when the rubber eyecup that Edmund supplies with these eyepieces is used, but is present nonetheless.

Yes, if Edmund started calling these Umlautz Konigfarben oculars, made with EckhardWerk glass, and listed them at $600 apiece, well... there would most likely be a thread twenty pages long regarding them :lol:

#6 ErnieM

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Posted 11 February 2012 - 10:32 PM

How about a link as to who sells the RKE.

#7 Vondragonnoggin

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Posted 11 February 2012 - 10:35 PM

I got it double dosed in my binocular telescope! Love this eyepiece! Works like a charm in all my scopes. I was lucky enough to stumble upon it with an astroscan I bought used for $30.00. Sits right next to my most expensive eyepieces with no problem. I also use it in my 5x Powermate for planetary and globulars. It's definitely got some magic to it.

#8 mgb

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Posted 11 February 2012 - 10:36 PM

Here it is:

Edmund Optics RKE

#9 amicus sidera

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Posted 11 February 2012 - 10:37 PM

Edmund Optics RKE line

#10 iceblaze

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Posted 11 February 2012 - 10:37 PM

http://www.edmundopt...?productid=2075 :whistle:

EDIT: Argg... you beat me to it Amicus :lol:

#11 ErnieM

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Posted 11 February 2012 - 11:06 PM

Thanks for the link.Now I am OCDing for another EP. :D

#12 JIMZ7

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Posted 12 February 2012 - 01:21 AM

I bet its all about the eye relief which is 24.5mm. I had a older Celestron 26mm "silvertop" Plossl with a 24mm eye relief which made the image "pop-out" at you--giving you the "wow" effect. The 28mm Edmund RKE gives you the same feeling I'm sure.

Jim :refractor:

#13 izar187

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Posted 12 February 2012 - 07:05 AM

It's a beauty of an ep for sure. I'm certainly keeping mine.
But being a three element design, it does plays best with slower focal ratios.

#14 Blake Andrews

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Posted 12 February 2012 - 11:23 AM

I bet its all about the eye relief which is 24.5mm. I had a older Celestron 26mm "silvertop" Plossl with a 24mm eye relief which made the image "pop-out" at you--giving you the "wow" effect. The 28mm Edmund RKE gives you the same feeling I'm sure.

Jim :refractor:


I've been wondering about this effect as well for many years. I've seen it in the two lowest power RKE's as well as the 26mm and 30mm Celestron Silvertop Plossls. The 2" 48mm Brandon also seems to produce this effect. I've always wondered if this is an optical characteristic that can actually be quantified and designed for.

Who knows? :shrug:

I'd love to here from someone more versed than I in optical engineering, voice their opinion on this topic. Any takers?

Cheers,
Blake

#15 SATMAN

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Posted 12 February 2012 - 11:49 AM

RKE's are some of the best kept astronomy secrets, the vintage late 1970's models are great , my best view with the 28mm RKE was of M42 with a vintage Tinsley 4" Refractor the view was absolutely breathtaking the wings of the nebulae very pronounced and the mottled appearance above the "fish mouth" clearly seen with direct vision no other eyepiece that I own shows this as clearly, that eyepiece is very special and the eyepiece disappears effect is quite profound . The entire RKE line works great in my 4" LOMO Astele MAK.

#16 BillP

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Posted 12 February 2012 - 12:11 PM

I don't think it is an "optical" characteristic, but more the interplay between the top housing, thickness of the side housing, and the ER distance, and the AFOV size. As Jim mentioned the 26 SilverTop does something like this...and it does. It is not as pronounced as the RKE, but extremely similar. With the SilverTop one can still see the bright silver ring of the top housing framing the FOV. With the RKE you see nothing but black and if the background around your scope is very dark, then all you really see is an image of the stars floating there before you. Now one could expect the 25mm ABBE to be similar since its ER is quite long and the housing quite thin, but it does not produce it at all...probably due to the smaller AFOV and a lot of stuff surrounding stays within you foveal vision. With the RKE and SilverTop, the AFOV is wide enough that the edges of the eyepiece are more in the peripheral areas of your vision which is less distinct. So IMO all these factors come into play and when they are all just right...magic :)

#17 Daniel Mounsey

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Posted 12 February 2012 - 12:54 PM

The Edmund 28 RKE is in my top ten list of favorite eyepieces of all time. Incredibly unique.

#18 Paraclete

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Posted 12 February 2012 - 01:01 PM

It seems to me that the 28mm RKE has a faithful cult following. I can sure understand why! :)

#19 Paraclete

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Posted 12 February 2012 - 01:09 PM

The AFOV also seems much wider than I expected. I was expecting it to be similar to my 40mm Plossl (similar AFOV as stated by the manufacturer), but things seemed much more wide-open than in the Plossl.

I find it mind-boggling that I enjoy this eyepiece more than Naglers, Ethos, Pentax's and Brandon's. I mean it only cost $62.50!

The 28mm RKE is not for everybody. But for those of us who enjoy it, we seem to enjoy it a lot! :)

#20 Deep13

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Posted 12 February 2012 - 01:10 PM

They're pretty nice. I have pairs of 28s, 21s, 15s and a single 12 and 8. But, you're right, the 28 is the one where the image really jumps out.

#21 Jeff B

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Posted 12 February 2012 - 08:07 PM

If you liked the 28MM RKE, you'll also like the Edmund 28MM Plossl.

BTW the 28MM RKE has always caused a stir from time to time and is probably the most talked about eyepiece ever, IMO.

Jeff

#22 starpal

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Posted 13 February 2012 - 01:00 AM

Surprising but no one seems to have mentioned the bit of a trick involved to hold the view. Never been an especially easy one to snatch a hold of for me, at least compared to many other eyepiece design offerings in similar FL and barrel size. I also believe the AFOV is closer to 50 degrees in some instances.

#23 Lane

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Posted 13 February 2012 - 01:11 AM

You have me very interested since I am about to get some binoviewers and this sounds like something I could use in them.

Is it a 1.25" barrel?

Does it have edge issues in fast refractors, F/5.5? and F/6.5?

#24 Vondragonnoggin

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Posted 13 February 2012 - 02:24 AM

AFOV is 45 degrees. No edge problems at F/6.5. There is a trick to no blackouts - keep your eyes at stated eye relief and centered. Once you get the trick, that's where the magic happens. This one is not for everyone. I recommend buying one before shelling out for two.

#25 Sgt

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Posted 13 February 2012 - 06:28 AM

I too wonder if this 'floating image' sensation happens when binoviewing 2 RKEs?


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