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Equipment Discussions >> Classic Telescopes

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droid
rocketman
*****

Reged: 08/29/04

Loc: Conneaut, Ohio
Re: Was going to nab new RKEs to complete my set and.. new [Re: actionhac]
      #5645893 - 01/27/13 11:41 AM

Yeah the new RKEs are now 85.00 a pop. holy cow

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rustynailz911
Pooh-Bah


Reged: 01/30/08

Re: Was going to nab new RKEs to complete my set and.. new [Re: actionhac]
      #5645917 - 01/27/13 11:55 AM Attachment (11 downloads)

Terra i love my pre RKE K28mm from Carton it is a awesome piece of glass.In my 60mm f7 it gives me a massive 3.3 deg fov and is sharp right to the edge of the field.It was really nice during the conjunction of Jupiter and the Moon last week i could fit it everything in the FOV.I think the ultimate would be to have 2 if em in a binoviewer.

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terraclarke
Post Laureate
*****

Reged: 05/29/12

Loc: Just South of the Mason-Dixon ...
Re: Was going to nab new RKEs to complete my set and.. new [Re: actionhac]
      #5645944 - 01/27/13 12:14 PM

Okay, now I'm confused. The add above says the ep has two achromats, i.e. two doublets, however both the Kellner and RKE consist of a singlet and a doublet. In the case of the Kellner, the doublet is the eye lens, and with the RKE it's the field lens. With the Kellner, the achromat is Plano-convex, positive side facing the field lens, with the RKE the positive side of the achromat faces the eye lens. The optics of the two eps are essentially reversed. So again, two achromats? What gives? Sounds more like a plossl.

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rdandrea
Carpal Tunnel
*****

Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: Was going to nab new RKEs to complete my set and.. new [Re: terraclarke]
      #5645978 - 01/27/13 12:32 PM

Quote:

So again, two achromats? What gives? Sounds more like a plossl.




Or a symmetrical/dialsight. I don't recall whether anyone has disassembled one and posted pictures to CN.


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bremms
Carpal Tunnel
*****

Reged: 08/31/12

Loc: SC
Re: Was going to nab new RKEs to complete my set and.. new [Re: terraclarke]
      #5645979 - 01/27/13 12:32 PM

The early "RKE" was Plossl or symmetrical, not a Kellner. It wasn't an RKE. Took mine apart at some time in the mid 80's and it has two achromats. Not positive if it was symmetrical, but pretty sure it was. The RKE was a better eyepiece.

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bremms
Carpal Tunnel
*****

Reged: 08/31/12

Loc: SC
Re: Was going to nab new RKEs to complete my set and.. new [Re: bremms]
      #5645983 - 01/27/13 12:35 PM

There is one of the old ones( 79.00??) and a "real" RKE on the bay right now. $79.00 is wayyyy to much for the old Carton. A newer RKE or circle NJ 32mm TV plossl will be better

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refasali
member


Reged: 01/28/12

Loc: Oregon & Washington
Re: Was going to nab new RKEs to complete my set and.. new [Re: terraclarke]
      #5646028 - 01/27/13 01:05 PM

from the same catalog, just opposite the eps in question


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actionhac
Post Laureate
*****

Reged: 08/09/08

Loc: Seattle
Re: Was going to nab new RKEs to complete my set and.. new [Re: refasali]
      #5646112 - 01/27/13 01:47 PM

A traditional standard Kellner has a doublet eye lens and a singlet field lens.
The RKE (Rank Kellner Eyepiece) appears to be the reverse of above and the elements are modified.
Also Type 2 and 3 Kellners exist.
The old version of the Edmund 28mm (1 1/8") could be one of these type 2 or 3 Kellner variations, whatever they are like, but 2 doublets doesn't seen to fit the Kellner profile does it, but in fact the 2 doublets may possess some technical/design feature that allows it to remain a Kellner, sort of like poor Pluto, a dwarf, but still a planet.
They may be something cooked up for the military, I think we should look into the Type 2 and 3 Kellner.

RKE cutaway:
http://www.handprint.com/ASTRO/ae2.html#eyeterms

Robert


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rdandrea
Carpal Tunnel
*****

Reged: 06/13/10

Loc: Colorado, USA DM59ra
Re: Was going to nab new RKEs to complete my set and.. new [Re: actionhac]
      #5646120 - 01/27/13 01:53 PM

Type III Kellner is discussed here:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/1,2,3,4,5,6,7,8,9,10,11/Number/5204908/Main/5202111


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refasali
member


Reged: 01/28/12

Loc: Oregon & Washington
Re: Was going to nab new RKEs to complete my set and.. new [Re: actionhac]
      #5646505 - 01/27/13 05:33 PM

Ah- there's a Kellner type I, II, III mention in the old Edmund optical books... I the believe the following is from All About Telescopes (1975)


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actionhac
Post Laureate
*****

Reged: 08/09/08

Loc: Seattle
Re: Was going to nab new RKEs to complete my set and.. new [Re: refasali]
      #5646808 - 01/27/13 07:53 PM

That book is a masterpiece.



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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Was going to nab new RKEs to complete my set and.. new [Re: Preston Smith]
      #5647188 - 01/27/13 11:37 PM

Quote:

Quote:

You need to take your time and find the right eye placement then they're very sweet.




I could not have stated it any better! It always takes a second or two to get your eye placement just right with that eyepiece. I enjoy the views with mine.




I love my set of RKE"s! Only bad thing about using the
28 is there is so much eye relief I have trouble using it in the City with street lamps, I use an eye cup, The image does seem to float in front of your eyes.
I use them as my main eyepieces and am not ashamed to say so!
You do have to keep bottom covers on to keep dust off the bottom lens cause it will drive you cray with the spots!
I love the 15, 12, and 8 mm in my Bino Viewer.
I cut my teeth on small field eyepieces so I don't need the 80 degree AFOV. They are very very bright and sharp in the center of the field.


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Jaimo!
Pooh-Bah
*****

Reged: 10/11/07

Loc: Exit 135 / 40° North
Re: Was going to nab new RKEs to complete my set and.. new [Re: orion61]
      #5649025 - 01/28/13 07:25 PM

The Pre-RKE's are actually asymmetrical Plössls similar to Clave's, and I find I prefer the Pre-RKE views over the RKE:





I was even able to snag a 1" version on the bay, it has the same lens arrangement as the 1 1/8"



Jaimo!


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