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Equipment Discussions >> Eyepieces

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RogerC
member


Reged: 04/06/09

Origins of Ploessl Eyepiece
      #5626474 - 01/16/13 04:05 PM

Hi, All.

In case anyone is interested, I've just published an article about the origins of the Ploessl eyepiece, and how this 20th c. invention became connected to the 19th c. Viennese optician GS Ploessl. The connection has been rather shrouded in mystery in the past.

The article is available in the Journal of the Antique Telescope Society. http://webari.com/oldscope/

Cheers,
Roger Ceragioli


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RogerC
member


Reged: 04/06/09

Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5626485 - 01/16/13 04:09 PM

I've been instructed that the correct URL is: http://oldscope.org/

Cheers,
Roger


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Mark9473
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Reged: 07/21/05

Loc: 51°N 4°E
Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5626491 - 01/16/13 04:11 PM

So where on that site is your article?

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RogerC
member


Reged: 04/06/09

Re: Origins of Ploessl Eyepiece new [Re: Mark9473]
      #5626507 - 01/16/13 04:18 PM

Hi, Mark.

The paper isn't posted online. It is an old-fashioned research article, scholarly in content, about 25 pages. You have to contact the ATS to order a copy for a small fee. I'm not allowed to distribute it for free. It is copyrighted to the ATS.

Cheers,
Roger

Edited by RogerC (01/16/13 04:19 PM)


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Mark9473
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Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5626513 - 01/16/13 04:21 PM

Hahaha, well that fits that type of Society. I'll revert to Wikipedia, thanks.

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RogerC
member


Reged: 04/06/09

Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5626554 - 01/16/13 04:39 PM

The bibliographic citation is:

Ceragioli, R., "Georg Simon Ploessl and his Namesake Eyepiece," Journal of the Antique Telescope Society, 36 (Fall, 2012), 2-24.

On the www.oldscope.org URL, click on "contact us." You can email Walt Breyer of the society, to obtain a copy, if interested.

Roger Ceragioli


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BillP
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Reged: 11/26/06

Loc: Vienna, VA
Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5626764 - 01/16/13 06:37 PM

Hi Roger! Thanks for the information. Have contacted them and look forward to the read.

Appreciated,
-Bill


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MRNUTTY
Carpal Tunnel
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Reged: 11/22/11

Loc: Mendon, MA
Re: Origins of Ploessl Eyepiece new [Re: BillP]
      #5626898 - 01/16/13 08:00 PM

How did it go from Ploessl to Plossl? Or did it?

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Jim Nelson
scholastic sledgehammer


Reged: 05/10/05

Loc: SE Michigan
Re: Origins of Ploessl Eyepiece new [Re: MRNUTTY]
      #5626919 - 01/16/13 08:10 PM

"Ploessl" is an alternate way of spelling "P-l-o with an umlaut-s-s-l."

Technically there is no "Plossl" eyepiece (o without an umlaut), but since umlauts are difficult to type w/standard keyboards and fonts, "Plossl" is used casually.

See the umlaut!:

http://www.televue.com/engine/TV3b_page.asp?id=51


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RogerC
member


Reged: 04/06/09

Re: Origins of Ploessl Eyepiece new [Re: BillP]
      #5626932 - 01/16/13 08:15 PM

Hi, Bill.

Sure. Hope you like it.

Any idea when your book will appear? I'm looking forward to it!

Cheers,
Roger


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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

Loc: Los Angeles
Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5626951 - 01/16/13 08:26 PM

Roger,
This would appear to contradict many previous descriptions of the development of the "Plössl" eyepiece (there are 3 variations of it he designed himself), as in:
http://www.astrosurf.com/re/evolution_of_eyepieces.pdf
and other works.
Did you look at his original work and patents?
How does that make modern versions something other than copies of that design?


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BillP
Postmaster
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Reged: 11/26/06

Loc: Vienna, VA
Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5627109 - 01/16/13 10:03 PM

I hope early March. In review now.

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Jaimo!
Pooh-Bah
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Reged: 10/11/07

Loc: Exit 135 / 40° North
Re: Origins of Ploessl Eyepiece new [Re: Jim Nelson]
      #5627223 - 01/16/13 11:22 PM

Quote:

"Ploessl" is an alternate way of spelling "P-l-o with an umlaut-s-s-l."

Technically there is no "Plossl" eyepiece (o without an umlaut), but since umlauts are difficult to type w/standard keyboards and fonts, "Plossl" is used casually.

See the umlaut!:

http://www.televue.com/engine/TV3b_page.asp?id=51




On a windows machine, using just about any font:

umlaut ö = alt+0246

degrees° = alt+0176


Jaimo!


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Jim Curry
Pooh-Bah
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Reged: 10/29/07

Loc: STL
Re: Origins of Ploessl Eyepiece new [Re: Jaimo!]
      #5627495 - 01/17/13 06:37 AM

great article, Roger. Thanks. (I read it in my ATS newsletter)

Jim


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Origins of Ploessl Eyepiece new [Re: Jim Curry]
      #5627959 - 01/17/13 12:03 PM

Plössl - pronounced something like "plersl." "Nagler Plössl" would be pronounced "nehgler plersl." Or it should be.


Mike


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DaveJ
Carpal Tunnel
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Reged: 01/07/05

Loc: NE Ohio
Re: Origins of Ploessl Eyepiece new [Re: Sarkikos]
      #5628139 - 01/17/13 01:54 PM

Quote:

Plössl - pronounced something like "plersl." "Nagler Plössl" would be pronounced "nehgler plersl." Or it should be.




Perhaps so, but the man himself (Uncle Al) says "Naygler Plahsl"


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Origins of Ploessl Eyepiece new [Re: DaveJ]
      #5628156 - 01/17/13 02:04 PM

I read in one blog that himself pronounces Nagler somewhere between an "ah" as in "Bach" and an "a" as in "bat." That would be about right. But "Plahsl" is just plain wrong.


Mike


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SteveTheSwede
member


Reged: 09/28/09

Loc: Stockholm, Sweden
Re: Origins of Ploessl Eyepiece new [Re: Sarkikos]
      #5628158 - 01/17/13 02:06 PM

Quote:

Plössl - pronounced something like "plersl." "Nagler Plössl" would be pronounced "nehgler plersl." Or it should be.


Mike




Well, bit more like this:
The PL is hard and short like the "pl" in Pluto.
The Ö-sound isn't exactly a part of the English language (which is why the letter isn't used, one suspects) but the closest sounds I can think of would be the "u" in "lurk" or "i" in "dirk" ( a bit depending on accent but you get the idea).
And finally SSL like the "sl" in "slacker".

It's two syllables: plö-ssl

Steve


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Origins of Ploessl Eyepiece new [Re: SteveTheSwede]
      #5628161 - 01/17/13 02:08 PM

Steve,

Yep, you've got it.

Mike


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BillP
Postmaster
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Reged: 11/26/06

Loc: Vienna, VA
Re: Origins of Ploessl Eyepiece new [Re: Sarkikos]
      #5628175 - 01/17/13 02:16 PM

Quote:

Plössl - pronounced something like "plersl." "Nagler Plössl" would be pronounced "nehgler plersl." Or it should be.


Mike




I think I will continue to pronounce it the way that is least effort - plah sul


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csrlice12
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Reged: 05/22/12

Loc: Denver, CO
Re: Origins of Ploessl Eyepiece new [Re: BillP]
      #5628202 - 01/17/13 02:33 PM

I don't worry about pronouncing it, I'd rather look thru it........

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DaveJ
Carpal Tunnel
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Reged: 01/07/05

Loc: NE Ohio
Re: Origins of Ploessl Eyepiece new [Re: Sarkikos]
      #5628231 - 01/17/13 02:51 PM

Quote:

I read in one blog that himself pronounces Nagler somewhere between an "ah" as in "Bach" and an "a" as in "bat." That would be about right. But "Plahsl" is just plain wrong.




Haven't we had this argument err, discussion before on CN? I've asked Al at NEAF exactly how to pronounce his name and his response was NAY-gler. I thanked him for clearing that up for me since our astronomy club members were curious. We had one of our members who constantly pronounced it as NAG-ler which Al said is not the way his name is pronounced. It's a name and the holder of the name gets to pronounce it the way they want. Al chooses to pronounce it NAY-gler. Who are we to say he's wrong?


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Origins of Ploessl Eyepiece new [Re: BillP]
      #5628251 - 01/17/13 03:01 PM

When a foreign word is pronounced incorrectly often enough and long enough by native speakers of English, it will become a de facto English word. Is Plossl one of ours now?


Mike


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Origins of Ploessl Eyepiece new [Re: DaveJ]
      #5628255 - 01/17/13 03:04 PM

Quote:

Al chooses to pronounce it NAY-gler. Who are we to say he's wrong?




Ah ... speakers of German? But I won't press it.


Mike


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rathbaster
scholastic sledgehammer
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Reged: 03/21/08

Loc: East Bridgewater, MA
Re: Origins of Ploessl Eyepiece new [Re: csrlice12]
      #5628468 - 01/17/13 05:01 PM

Quote:

I don't worry about pronouncing it, I'd rather look thru it........






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SteveTheSwede
member


Reged: 09/28/09

Loc: Stockholm, Sweden
Re: Origins of Ploessl Eyepiece new [Re: Sarkikos]
      #5628480 - 01/17/13 05:07 PM

Quote:

When a foreign word is pronunced incorrectly often enough and long enough by native speakers of English, it will become a de facto English word. Is Plossl one of ours now?


Mike




Oh, you mean as opposed to foreign words pronounced correctly, like for example... um.... eh...


Steve


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Origins of Ploessl Eyepiece new [Re: SteveTheSwede]
      #5628492 - 01/17/13 05:15 PM

Hmmm.... Not so much around here, I guess, except mostly by the foreigners.


Mike


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RogerC
member


Reged: 04/06/09

Re: Origins of Ploessl Eyepiece new [Re: Starman1]
      #5628508 - 01/17/13 05:23 PM

Hi, Don.

My paper attempts to trace the developments back to Ploessl himself, using all original documents. The earliest are all in German, a few in French, and the most recent in English. I have translated the German and French into English where needed. It is for readers of the article to decide whether it is convincing.

GS Ploessl himself certainly designed no eyepieces in the modern sense. He was a fabricating optician, mainly focused on building microscopes. Rather, he replaced the plano-convex singlets of the Wilson-type eye-loupe with cemented plano-convex achromats. That is, he built in essence achromatized Ramsden eyepieces. But they still had a large air-gap, as far as I can tell. A few of these eyepieces exist in Europe, but I have not had an opportunity to examine any. My information is derived from 19th century descriptions/illustrations as indicated in the paper. They were low-power microscope eyepieces.

It was Albert Koenig, apparently, the great Zeiss designer who around 1915 in seeking for a better eyepiece for military sighting instruments, removed the unneeded airgap and began experimenting with use of high-index of refraction glasses and "bending" of the lens doublets to achieve higher performance. Similar developments happened at Goerz and elsewhere.

Many eyepieces of similar performance (and various usable field sizes) were developed between about 1890, starting with the Abbe Ortho, leading through WWI, with Erfle's various designs, and on to WWII. Koenig's own designs as shown by his American & German patents, and German publications (cited in the paper) centered on binocular or gunnery eyepieces of large eyerelief (as understood then). The most advanced 2-2 eyepiece of Koenig was patented in the years around 1940 in Germany and the US. Koenig began calling the design "the orthoscopic according to Ploessl" as a way to distinguish it from "the orthoscopic according to Abbe." All this is discussed and documented from orignal sources in the paper.

Many many eyepieces of this general type (2-2) were developed and used in military equipment such as tank telescopes, dial-sights, binoculars, etc. in WWII. They can be seen clearly in WWII documents in my collections. The most advanced, such as one devised by Chester Brandon, where asymmetrical 2-2 forms similar to Koenig's most advanced type. This is the type of the Brandon still today, I'm told. Other forms were simpler, symmetrical 2-2 types.

It was after the war that the "Ploessl" as we know it for amateur astronomers took off, through the work of Brandon, Jean Texereau/Clave, and finally Al Nagler. But the details and documentation are best seen in the article itself.

In the 50s and 60s in the US, since the name Ploessl was still very unfamiliar, people such as Edmund sold WWII surplus eyepieces (derived from military equipment) under such names as Kellner Type 3, etc. But they were Ploessls of various types, and some indeed were Brandons, I'm told.

I will be very glad to see Bill's book soon.

Cheers,
Roger


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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

Loc: Los Angeles
Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5628671 - 01/17/13 06:57 PM

Roger,

Will you be suggesting changes to all the Wikipedia pages about Plössl?
Because there are innumerable pages that are then incorrect if what you assert is true.

If you send me an email address in a PM, I can send you Chris Lord's email address, too. I think he and some of his cronies would like to be updated since they are responsible for many "documentations" of Plössl's work.

Clavé's literature accompanying their eyepieces (I bought several in the '70s) mention Plössl, but never mention König as a source for the closely-spaced 2:2 design.

I guess the entire world has been wrong for well over a century.


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Svezda
scholastic sledgehammer


Reged: 06/01/07

Loc: Texas
Re: Origins of Ploessl Eyepiece new [Re: DaveJ]
      #5629256 - 01/18/13 01:35 AM

Quote:

Quote:

I read in one blog that himself pronounces Nagler somewhere between an "ah" as in "Bach" and an "a" as in "bat." That would be about right. But "Plahsl" is just plain wrong.




Haven't we had this argument err, discussion before on CN? I've asked Al at NEAF exactly how to pronounce his name and his response was NAY-gler. I thanked him for clearing that up for me since our astronomy club members were curious. We had one of our members who constantly pronounced it as NAG-ler which Al said is not the way his name is pronounced. It's a name and the holder of the name gets to pronounce it the way they want. Al chooses to pronounce it NAY-gler. Who are we to say he's wrong?



Not being a German language expert but having studied it for four years for my first bachelor's degree, I'd bet that Al's pronunciation indicates that the surname originally used an a-umlaut but got anglicized to be spelled without it (just using the 'a').

Regarding 'Ploessl', sure, no one can force you to pronounce it correctly, but considering it is a surname and, as the poster quoted above pointed out, the owner of said surname has a right to say it as he likes, well, Mr(Dr.?) Ploessl would have pronounced his name as was indicated earlier - 'Plerssl'. This is as close as you can get, I think, with the English alphabet.


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cjc
sage


Reged: 10/15/10

Loc: Derbyshire, England
Re: Origins of Ploessl Eyepiece new [Re: RogerC]
      #5629297 - 01/18/13 02:59 AM

Roger, I appreciate that you cannot reproduce the article so many thanks for your summary.

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BillP
Postmaster
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Reged: 11/26/06

Loc: Vienna, VA
Re: Origins of Ploessl Eyepiece new [Re: Starman1]
      #5629590 - 01/18/13 10:02 AM

Quote:

...König as a source for the closely-spaced 2:2 design.





Look at figure 4 from this 1915 Konig Patent -- http://ip.com/pat/US1159233

Look at figure #2 from this 1940 Konig Patent -- http://www.google.com/patents?id=gflYAAAAEBAJ&pg=PA2&dq=ininventor:"A...

**Sorry for the long paths...the URL function seems to not be working for me.



Edited by BillP (01/18/13 10:18 AM)


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RogerC
member


Reged: 04/06/09

Re: Origins of Ploessl Eyepiece new [Re: Starman1]
      #5632367 - 01/19/13 10:39 PM

Hi, Don.

It is not for me to "correct" other people's work. It is for other people to decide if I am correct, after reading the article and carefully weighing the evidence that I have tried to bring to bear. And there is much evidence from original documents.

Cheers and all the best,
Roger

PS We have tried to be similarly careful in the writing of our book, Telescopes, Eyepieces, and Astrographs (Willmann-Bell, 2012). All the best.


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Mak2007
professor emeritus


Reged: 06/24/07

Re: Origins of Ploessl Eyepiece new [Re: BillP]
      #5635941 - 01/21/13 11:20 PM

Quote:

Quote:

...König as a source for the closely-spaced 2:2 design.





Look at figure 4 from this 1915 Konig Patent -- http://ip.com/pat/US1159233

Look at figure #2 from this 1940 Konig Patent -- http://www.google.com/pate nts?id=gflYAAAAEBAJ&pg=PA2&dq=ininventor:&...

**Sorry for the long paths...the URL function seems to not be working for me.






Hi Bill,
So, are Brandons actually Konig's design?
Just wondering in good faith


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BillP
Postmaster
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Reged: 11/26/06

Loc: Vienna, VA
Re: Origins of Ploessl Eyepiece new [Re: Mak2007]
      #5637342 - 01/22/13 05:00 PM

I would say that there is no way to know (without lab tests). I hear lots of claims made about the eyepiece, like glass types used and such, but can get zero confirmation on it. I have asked Don to comment on if indeed the eyepiece uses several glass types, if it is non-symmetrical, and such, but no response. All that is on record from the manufacturer about their eyepieces is that they incorporate the original optical designs of Chester Brandon and have 4 elements. Kindof vague.

I have an 8mm at home. Not obvious how it comes apart. Has anyone taken a Brandon apart?? All this can validate is the arrangement, # elements, and the surface curves...not the glass types.

From a behavioral perspective, the off-axis of a Brandon acts more like a Konig than it does like a Plossl. Takes a much longer focal length scope to clean up its off-axis entirely...just like a Konig. Plossls clean up at much shorter focal ratios than do Konigs or Brandons.


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