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Can you folks tell if the all the lens surfaces are coated on the red rubber model, no rubber model and old 1 1/8" model?

Thanks

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Apo would be perfectly fine. APO stands for Adirondack Public Observatory, Army Post Office, and a variety of other things.

It's the all caps that makes it - well, stupid. But I guess everyone must conform so they won't upset the rest of the herd.

Clear skies, Alan

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The Backyard Astronomer's Guide (Dicksinson & Dyer) it says "Now discontinued, Edmund Scientific's RKE design (for David Rank modified Kellner for Edmund) reversed the lens elements from the standard arrangement, giving it a wider field (45 degrees)"

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If you read Mike Hosea's research, you would see that it is very likely references to reversed lenses from a Kellner arrangement are most likely incorrect. That would mean not only did D & D (among a host of others) get the description wrong, but they got the naming reference wrong. Poor reflection on the research of that item (in an otherwise very good book). Rather poor reflection on the editors to boot.

edz

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From BillP's RKE thread (p.5) is this post by RogerC:

"Indirectly, through the Antique Telescope Society listserve, we got a message from Terry Dickinson, well-known author of "Backyard Astronomer's Guide" and other things, that Robert Edmund told him that RKE means "Rank modified Kellner for Edmund, honoring the designer, David Rank, a physics prof at Penn State and noted optics expert of the mid-20th century." And that: "It could also stand for Rank Keller Eyepiece, and Robert accepted that after a while." Dickinson refers to p. 70 of the 3rd edition of his book, which I don't have. He says he consulted for Edmund in the 1970s."

The above quote makes it apparent that Dickinson & Dyer did not just pull off their published definition of RKE from thin air, but rather, the source was from Robert Edmund himself. They have, after all, a reputation to protect. Knowing this bit of info now, it seemed imprudent for anybody to say that such was a poor reflection of research & persona of D & D and their editors. Thanks.

Given all this, there are apparently 3 official meanings of RKE, all company-accepted (the latter 2 not in writing):

1. Rank, Kaspereit, Erfle (from trademark)
2. Rank modified Kellner for Edmund (from Robert Edmund/D&D + Edmund executive)
3. Rank Kellner Eyepiece (eventually accepted by Robert Edmund/Dickinson + Edmund staff)

So, Lawrence Sayre and a host of others like Amicus Sidera et. al. were right all along.

The only question now is why, for the longest time, was "Rank, Kaspereit, Erfle" hidden or never mentioned before by the Edmund company and it took a BillP's clever sleuthing to ferret it out?

P.S. I have emailed Mr. Dickinson through their Backyard Astronomer's Guide website regarding the matter to confirm what Mr. Robert Edmund had said about what "RKE" stood for; will post when I receive a reply from him.

Best,

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I'm quite happy with this analysis, and see no reason to consider the rather odd Rank, Kaspereit, Erfle as the lone interpretation.

Heck, people still feel APO is an appropriate abbreviation for apochromat.

Clear skies, Alan

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Thank you very much sir!!!

Best,

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Can you folks tell if the all the lens surfaces are coated on the red rubber model, no rubber model and old 1 1/8" model?

Thanks

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My completely unmarked, pre RKE, all black aluminum, no red rubber, 2 achromat, assumed to be 28mm (1 1/8") f.l., does not appear to have any coatings on any lens. I've tried every which way see some hint of coatings, but I think it is just wishful thinking. On the other hand, all of the real RKE, 3 element, red rubber grip models that I have seen are definitely coated on the eye lens. I'm not sure about the other surfaces since I have yet to disassemble one of my own.

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Will confirm that on the RKE28 red-grip version (Edmund Scientific in this case), the eye lens is coated (shown at right in pic below):


RKE 28mm Edmund Scientific: left: field lens; right: eye lens

The field lens (shown at left in pic above) is coated as well on both sides like the eye lens, although the coatings are very light as to escape notice in a cursory inspection. Tried to capture the purplish/bluish coating reflections shown above by shooting the lens at certain angles.

Best,

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... I can easily imagine that M42 would look amazing for example.

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Mark8888 wrote:

Someone in one of these recent RKE threads described the view like a veil had been lifted. I saw that too. Compared to a pair of 24 pans, the view was brighter, and also sharper. My wife noticed it too, immediately. I compared the 2 pairs a few times to confirm it. Now, I know that the decrease in magnification must be a big part of the difference, as any extra mag will make the view darker and also make the view a little less crisp, especially a view over hot land, but still... what else might be causing the difference? Less glass?

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I cast my vote for less glass, although I'm sure the heavyweights will appear shortly to attempt laying waste to that hypothesis.

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Your first good look at M42 will 100% convince you that your money was well spent. (M81 and 82 aren't bad either, but M42 is wonderful in the RKE's)

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After a few uses they also became my favorite lunar eyepieces.

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Hi all,

Due to this thread and other recent threads about RKE's, along with a friend buying one, I bought a pair from the Surplus Shed. I just couldn't take the heat anymore and wanted to see what was up. I received them today. It was cloudy tonight, obviously, so I used them on a few buildings and a pylon a few towns over, at what must be a distance of several miles. Here are a few first light observations.

So I put them in the binoviewer (TEC 140 scope, mark 5 bino). At the time my scope had 1.7x GPC in the bino, and also a barcon barlow in front of a 2 inch extension, so the magnification was quite high. WOW! Not a way to start. I realized that the eye relief was a mile back and the mag was way too high for staring at a bulding over hot land a few towns over, I couldn't even really form an image. I quickly decided to get rid of the barcon barlow, get rid of the 2 inch extension, and start again.

Now it was much easier to form a solid image. And what an image!! Observations:

* These are a lot of fun to use, no question. I immediately saw the eyepiece housing melt away and understood the "floating image" rep. of these eyepieces. I've never seen anything like it before.

* The eye relief was reduced to a degree I can deal with when I removed the barcon (but still had in the 1.7x GPC), but was still huge. I can imagine using these for short stints but perhaps not for hours at a time like I do with some other ones. It does take some effort to hover at exactly the right distance and in the right position, though I'm sure with more practice it would be easier. Although it wasn't easy, I didn't find it to be terribly difficult, either.

* Someone in one of these recent RKE threads described the view like a veil had been lifted. I saw that too. Compared to a pair of 24 pans, the view was brighter, and also sharper. My wife noticed it too, immediately. I compared the 2 pairs a few times to confirm it. Now, I know that the decrease in magnification must be a big part of the difference, as any extra mag will make the view darker and also make the view a little less crisp, especially a view over hot land, but still... what else might be causing the difference? Less glass? Anyway, it was a really bright, sharp view. And I didn't spend a lot of time inspecting the edges but they didn't jump out at me as being terrible, at least.

* The fov definitely seems much wider to me than it actually is.

* They're small!

* They were a little dusty when I got them and one was slightly unscrewed. No big deal.

* I was surprised at how parfocal they were with the pan 24's. I really didn't have to move the focuser much at all.

* I found it easier to hold the view steady while monoviewing.

So! I'm happy with them. Great view. Not sure about how often I'll use them due to the eye relief and actual fov, but perhaps a good amount on certain targets. Looking forward to doing some actual space viewing with them... I can easily imagine that M42 would look amazing for example.

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(p.s. to all, can we argue about the name enough to get this post up to 1000 replies?)

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They're doing that in the other thread as we speak.

Yeah, M42 starfield looks fantastic with the RKE28.

Best,

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Mark8888 wrote:

Someone in one of these recent RKE threads described the view like a veil had been lifted. I saw that too. Compared to a pair of 24 pans, the view was brighter, and also sharper. My wife noticed it too, immediately. I compared the 2 pairs a few times to confirm it. Now, I know that the decrease in magnification must be a big part of the difference, as any extra mag will make the view darker and also make the view a little less crisp, especially a view over hot land, but still... what else might be causing the difference? Less glass?

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I cast my vote for less glass, although I'm sure the heavyweights will appear shortly to attempt laying waste to that hypothesis.

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It's actually the RKE28 mystique now playing catch-up with the Brandon.

Best,

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Your first good look at M42 will 100% convince you that your money was well spent. (M81 and 82 aren't bad either, but M42 is wonderful in the RKE's)

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After a few uses they also became my favorite lunar eyepieces.

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A few days ago I looked at the 2012 Supermoon through the RKE28 + barlow and it looked splendid, sharp & crisp.

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(p.s. to all, can we argue about the name enough to get this post up to 1000 replies?)

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They're doing that in the other thread as we speak.

Yeah, M42 starfield looks fantastic with the RKE28.

Best,

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I am jealous!! M42 is behind a line of tall trees for me now With all this RKE talk...making me feel like getting all of them and not just the 28mm

btw, wanted to get all the name meaning specualtion back into the other thread where it better belongs. This thread is about what to expect performance-wise.

Edited by BillP (05/09/12 10:50 AM)

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Mark8888 wrote:

Someone in one of these recent RKE threads described the view like a veil had been lifted. I saw that too. Compared to a pair of 24 pans, the view was brighter, and also sharper. My wife noticed it too, immediately. I compared the 2 pairs a few times to confirm it. Now, I know that the decrease in magnification must be a big part of the difference, as any extra mag will make the view darker and also make the view a little less crisp, especially a view over hot land, but still... what else might be causing the difference? Less glass?

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I cast my vote for less glass, although I'm sure the heavyweights will appear shortly to attempt laying waste to that hypothesis.

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Actually I'd love to hear what the heavyweights would say about that hypothesis. The increase in brightness from the Pan 24 to the 28 RKE, to me, seemed like more than you'd expect from 4mm. The RKE did seem exceptionally bright, and also sharp, during the simple comparison I did of the two sets of eyepieces.

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