47 replies to this topic

[Steven C]

I purchased my University Optics 55mm Plössl 2" back in November of 1986 and still have it. In side-by-side comparisons, I always preferred this eyepiece over other standard Plössls. Recently I became aware that the same factory that made very desirable Masuyama eyepieces also made the University Optics 55mm Plössl and the Celestron 50mm Ultima. I was really curious so I carefully disassembled the eyepiece and lo and behold, it actually has 5 elements! I wonder how the configuration of this eyepiece compares to the Masuyama or the Meade 56mm Super Plossl. 

 

I would be very interested in any information or opinions that you might have with regard to the University Optics 55mm Plössl.

 

Here are some thoughts on the long focal length eyepieces that I currently own.

 

Celestron “Silvertop” 50mm Plössl 2” - smoothside. (purchased new in Nov 1985 and still own it)
• Awful Kidney Bean in moderate to severe light pollution and in the daytime (typical Plössl)
• Narrow AFOV – between 43° and 44°
• Sharp Image across the field
• Nice Coatings on all surfaces although I am sure modern coatings are a lot better.
• Slightly heavier than the University Optics 55mm Plössl.
• Body is sandblasted anodized aluminum with a black rim around the eyelens and has orange embossed lettering. Average metal barrel – to smooth to be solid metal so it is probably plated

 

Meade 56mm Super Plössl 2” 5 element pseudo-Masuyama - smoothside. (purchased new in Aug 1991 and still own it)
• Kidney Bean problems are a whole lot less that the Celestron 50mm Plössl. With some care, it can be used in daylight.
• AFOV – 52°
• Sharp Image across the field
• Nice Coatings on all surfaces although I am sure modern coatings are a lot better.
• Very Heavy Eyepiece especially when used with a 4” or 5” SCT.
• Black Annodized Aluminum with white embossed lettering. Barrel is obviously machined but very smooth and high quality – probably solid metal!

 

University Optics 55mm Plössl 2” (5 Element!! – perhaps pseudo Masuyama) - smoothside. (purchased new in Aug 1987)
• Rarely do I see the Kidney Bean. Works fine in the daylight.
• AFOV – 50°
• Sharp Image across the field
• Nice Coatings on all surfaces although I am sure modern coatings are a lot better.
• Body is painted black with White and Blue embossed lettering. Barrel is too smooth to be machined so it is probably plated.

 

Celestron 50mm Ultima 2” – 7 element eyepiece – Just acquired this beast and haven’t compared it yet.
• Less heavy than the Meade 56mm Super Plössl
• Very nice coatings
• Black Annodized Aluminum with embossed orange lettering. Barrel is obviously machined but very smooth and high quality – probably solid metal!

 

https://www.dropbox....Plossl.jpg?dl=0

 

{edited for grammar and added the picture}

Edited by Steven C, 01 December 2015 - 06:37 PM.

[Alvin See]

There were 45mm and 60mm Masuyamas, but nothing in between. Not a direct clone for sure.

[Mariner@sg]

I have one of the 55mm UO Plossls that I had purchased it off another CN user a few years back. I found the lenses riddled with many hairline scratches when first examined and had taken it apart to clean them. I found 4 elements in 2 cemented groups as per a plossl design.

[Scott99]

Wow, 5 elements in the UO 55mm, that is a fascinating find!  I had this eyepiece 2 different times and it seemed normal, never took it apart.  Do you have a picture of the eyepiece?  Would love to see it.  

 

I like this type of eyepiece for dark skies, the 50mm Tak LE is another excellent eyepiece, so is the Brandon 48mm.   The Tak is better for lower f-ratios.  

[junomike]

The UO 55mm I had was the same as the common others as seen on page 7 in the UO Brochure.

However.........Page 14 has a "Special Edition" which very much looks like it could be a 5-Element Masuyama Clone!!!!!

Interesting!

 

Mike

[junomike]

Steve C, Apparently these are numbered (only 500 made).  What number is yours?

Here's another pic of one from a thread a few years ago. Looks to be labelled as "Plossl II 55mm"

 

Mike

Edited by junomike, 30 November 2015 - 04:30 PM.

[Scott99]

Mike - thanks for posting that link to the UO catalog!  what a great trip down memory lane - so many great products from UO in those days.  The 80mm refractor kit was an excellent scope for the money.  All the great premium Japanese eyepieces with no annoying safety groove or heavy bodies.   The Klee barlow, all the konigs in 1.25" and 2" size, including regular Konigs in 30mm and 40mm and the 7/70 40mm eyepiece…..and the 2" prism diagonal was outstanding! 

 

I've been wishing I still had that diagonal lately.  In f/8 scopes or longer the konigs were were excellent, they had the contrast of an ortho with 60 degree field.  

 

So the 5-element Plossl can be identified by the higher eyeguard vs. the regular one.

Edited by Scott99, 30 November 2015 - 06:53 PM.

[Steven C]

Sorry, mine looks exactly like the one in the catalog above on page 7 or so and I purchased it from my 1986-87 catalog which I could scan and post. The 55mm Plossl is listed as NEW in the catalog.

 

Mine is certainly NOT the "Special Edition"  55mm Plossl II in the 1992 catalog! Paid only $91.50 shipped at the time. The price rose rapidly to ~110+S&H in the next catalog.

 

https://www.dropbox....lossl.jpg?dl=0 

 

I suppose I could dissemble it again and take a few pics if there are any doubters. I always wondered why the body was so long!

 

Has 2 cemented lenses in 2 groups that appear to be symmetrical and then that pesky 5th lens. There are absolutely no issues with the coatings. I keep my eyepieces in a well controlled environment so "there is no fungus among us"

 

Strange, but William Paolini's new book on eyepieces completely ignores this gem!

 

On reflection, it was my first wife (the War Department) that said I couldn't buy the Celestron 50mm 2" Silvertop so I settled for the much less expensive UO 55mm. Perhaps this, as it turns out, was  a serendipitous decision by my ex-wife. (P.S. I eventually got that Celestron 50mm 2" Silvertop! He He He).

Edited by Steven C, 01 December 2015 - 06:53 PM.

[Scott99]

Mine is certainly NOT the "Special Edition"  55mm Plossl II in the 1992 catalog! Paid only $91.50 shipped at the time. The price rose rapidly to ~110+S&H in the next catalog.

 

 

the plot thickens!  That looks like just like the ones I had, I never took them apart.  I wonder if they're all 5 elements…I doubt this is an isolated case.  Someone else is going to have to take one apart!

[Steven C]

I have one of the 55mm UO Plossls that I had purchased it off another CN user a few years back. I found the lenses riddled with many hairline scratches when first examined and had taken it apart to clean them. I found 4 elements in 2 cemented groups as per a plossl design.

 

 

Apparently, not ALL have 5 lenses. Mariner makes a valid point that his was only the standard 4 element symettrical Plossl. That indicates some mix between 5 and 4 elements. Maybe the early ones had 5 and then to reduce the cost, they became 4? Perhaps the UO story is similar to the Meade 56mm Super Plossl which initially had 5 elements and due to cost considerations, was reduced to the standard 4 element symettrical plossl design when the transition to rubber grips and eyecups were implemented.

 

An interesting puzzle to say the least. As I said, I always "liked" this eyepiece over standard 4 element plossls in side-by-side comparisons. I now have a substantive objective reason to support my subjective evaluation!

 

Even in comparisons to the Televue 55mm Plossl (smoothside & rubber eyecup versions) it stood out as better in the late '80's and early '90's.

 

Will be interesting to see how it compares with my (new to me) Celestron Axiom 50mm. Waiting for clear skies! Maybe up to 5-7 days before clear skies rule - this should be the "dry season" (very low humidity, clear skies day and night, warm sunny days with warm clear nights) here but the early and unexpected cold fronts from the north are disturbing the historical norms that occur this time of year! 

Edited by Steven C, 02 December 2015 - 03:49 PM.

[Dave Bush]

I've not had/seen the UO that you have but I can confirm that the 50mm Axiom = Tak 50mm LE = original Meade 56mm Super Plossl = 50mm Orion Optilux.

All were the same five-element design. This determined by disassembling them.

 

Now I can't say that all the lens curves were identical but they sure looked like they were a d all performed essentially the same for me. 

Edited by Dave Bush, 02 December 2015 - 07:10 PM.

[A6Q6]

I've had the 2"  55mm UO Plossl since 1979.  It was recommended and sold to me by Rodger W. Gordon who was the east coast rep for OTI, UO,  "ausJena, and others.    It was $79 and change. I haven't taken it apart but I'm sure its 4- elements.

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[Steven C]

I've had the 2"  55mm UO Plossl since 1979.  It was recommended and sold to me by Rodger W. Gordon who was the east coast rep for OTI, UO,  "ausJena, and others.    It was $79 and change. I haven't taken it apart but I'm sure its 4- elements.

 

unless you have dissembled it, how can you be sure? Shall I take your your statement as a challenge that says that I am mistaken?

Edited by Steven C, 02 December 2015 - 09:13 PM.

[A6Q6]

 

 

I would be very interested in any information or opinions that you might have with regard to the University Optics 55mm Plössl.

 

 

 

I've had the 2"  55mm UO Plossl since 1979.  It was recommended and sold to me by Rodger W. Gordon who was the east coast rep for OTI, UO,  "ausJena, and others.    It was $79 and change. I haven't taken it apart but I'm sure its 4- elements.

 

unless you have dissembled it, how can you be sure? Shall I take your your statement as a challenge that says that I am mistaken?

 

Wow, you said you were interested in "information or opinions" on the 2" 55mm UO eyepiece. I'm just giving you my "opinion," that I have only 4 elements, along with the possibility that I have one of the oldest examples of that eyepiece.   I have no reason to doubt that what you have has 5 elements.  If I thought you were going to take my post as a challenge, I would have not posted.   I thought about checking what was really inside my eyepiece before I posted,........... but that doesn't seem too important now.

 ,
 

Edited by A6Q6, 02 December 2015 - 10:51 PM.

[Dave Mitsky]

It certainly was interesting seeing that old University Optics catalog.  ASH owns one of what looks like the "Limited Edition" 55mm Plössls (Plössl-II?) and a 2" 32mm König-II shown there.  The club also has a 45mm University Optics Plössl that I picked up at a star party years ago, along with 25 and 40mm University Optics MK-70s.  A friend of mine owns the 32mm University Optics Wide Scan.

 

The 45mm Plössl looks very similar to the 55mm Plössl being discussed in this thread.  I have no idea how many lens elements it has.

 

Dave Mitsky

[Steven C]

 

 

 

I would be very interested in any information or opinions that you might have with regard to the University Optics 55mm Plössl.

 

 

 

I've had the 2"  55mm UO Plossl since 1979.  It was recommended and sold to me by Rodger W. Gordon who was the east coast rep for OTI, UO,  "ausJena, and others.    It was $79 and change. I haven't taken it apart but I'm sure its 4- elements.

 

unless you have dissembled it, how can you be sure? Shall I take your your statement as a challenge that says that I am mistaken?

 

Wow, you said you were interested in "information or opinions" on the 2" 55mm UO eyepiece. I'm just giving you my "opinion," that I have only 4 elements, along with the possibility that I have one of the oldest examples of that eyepiece.   I have no reason to doubt that what you have has 5 elements.  If I thought you were going to take my post as a challenge, I would have not posted.   I thought about checking what was really inside my eyepiece before I posted,........... but that doesn't seem too important now.

 ,
 

 

I wasn't doubting your statement or your veracity, I am just saying that I was absolutely sure that my UO 55 had only 4 elements from 1987 until last week - that is until I actually took it apart and was absolutely astonished that it had 5 elements.

Edited by Steven C, 03 December 2015 - 05:05 PM.

[A6Q6]

Hmmm looks like no Plossl to me!!

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Edited by A6Q6, 03 December 2015 - 09:18 PM.

[junomike]

So then what exactly are these?

 

Mike

[Steven C]

So then what exactly are these?

 

Mike

Excerpt from https://en.wikipedia...2Symmetrical.22

 

"Today it is a very popular design on the amateur astronomical market,[8] where the name Plössl covers a range of eyepieces with at least four optical elements."  

 

 

Excerpt from http://www.swindonst.../eyepieces.htm 

 

"Elements and groups - singlets, doublets & triplets

Eyepieces consist of several elements, 'elements' refers to the glass portion of the eyepiece, so if an eyepiece has four elements this means that it is made up of four peices of glass within which creates the maginification and the focal length of the eyepiece. Some of these 'elements' are cemented together and so a doublet means two pieces of glass cemented together and so on. Such a construction often consists of a singlet followed by a doublet or more. One of the most popular eyepieces, the Plössl, consists of a minimum of two doublets, for example, and may not have a singlet eye lens, although they are getting increasingly sophisticated!" 

 

The Wikipedia article seems to be woefully short on other designs of eyepieces, for instance, the Televue (Delos, Panoptic, WideField, etc.), the Celestron Axiom, Masuyama, Meade Super Plossl (pseudo Masuyama) and many others. Need to be updated!

 

Obviously, this is not any of the eyepieces depicted in Wikipedia except, perhaps, the Plossl but A6Q6, is there any possibility that you have the top lens reversed. That would give two symmetrical groups of two (the traditional Plossl) with an eyelens for ??? I didn't pay close enough attention when I took mine apart.

Edited by Steven C, 03 December 2015 - 05:58 PM.

[A6Q6]

 

So then what exactly are these?

 

Mike

Excerpt from https://en.wikipedia...2Symmetrical.22

 

"Today it is a very popular design on the amateur astronomical market,[8] where the name Plössl covers a range of eyepieces with at least four optical elements."  

 

 

Excerpt from http://www.swindonst.../eyepieces.htm 

 

"Elements and groups - singlets, doublets & triplets

Eyepieces consist of several elements, 'elements' refers to the glass portion of the eyepiece, so if an eyepiece has four elements this means that it is made up of four peices of glass within which creates the maginification and the focal length of the eyepiece. Some of these 'elements' are cemented together and so a doublet means two pieces of glass cemented together and so on. Such a construction often consists of a singlet followed by a doublet or more. One of the most popular eyepieces, the Plössl, consists of a minimum of two doublets, for example, and may not have a singlet eye lens, although they are getting increasingly sophisticated!" 

 

The Wikipedia article seems to be woefully short on other designs of eyepieces, for instance, the Televue (Delos, Panoptic, WideField, etc.), the Celestron Axiom, Masuyama, Meade Super Plossl (pseudo Masuyama) and many others. Need to be updated!

 

Obviously, this is not any of the eyepieces depicted in Wikipedia except, perhaps, the Plossl but A6Q6, is there any possibility that you have the top lens reversed. That would give two symmetrical groups of two (the traditional Plossl) with an eyelens for ??? I didn't pay close enough attention when I took mine apart.

 

All of them are upside down, I did it so it would be easy to put back together. Edit: I now show the top lens in post #17

Edited by A6Q6, 03 December 2015 - 09:21 PM.

[Mariner@sg]

It certainly was interesting seeing that old University Optics catalog.  ASH owns one of what looks like the "Limited Edition" 55mm Plössls (Plössl-II?) and a 2" 32mm König-II shown there.  The club also has a 45mm University Optics Plössl that I picked up at a star party years ago, along with 25 and 40mm University Optics MK-70s.  A friend of mine owns the 32mm University Optics Wide Scan.

 

The 45mm Plössl looks very similar to the 55mm Plössl being discussed in this thread.  I have no idea how many lens elements it has.

 

Dave Mitsky

 

Thanks for the post on the UO catalogue Dave! Very nice to see all those old glass but interestingly, not much info on the telecompressor, which I have and have no idea how it is used.

[Peter Besenbruch]

​​

So then what exactly are these?

 

​It looks like a variation on the König.

[Steven C]

​​

So then what exactly are these?

 

​It looks like a variation on the König.

Except that the Konig is a 3 lens eyepiece - not 5

[Peter Besenbruch]

​

 

​​

So then what exactly are these?

 

​It looks like a variation on the König.

Except that the Konig is a 3 lens eyepiece - not 5

 

​My understanding is that there were a number of variations that are called König.

 

A little edit: I found a PDF from the Brayebook Observatory which lists a number of types I have never heard of. König's name is everywhere, but there are two types that caught my eye. The first is the Straubel, "a 2-2-1 lens by Zeiss in which the apparent field is 70 ̊ at f/5 and eye relief 0.56Fe. The glasses used were dense flint, hard crown, and a low index, low dispersion FK3 flint." The field is a bit wide for the eyepiece here and the curves may be different.

 

The second is the modified Astroplan, also a 2-2-1, used by Takahashi and others in Japan. The regular Astroplan looks the the Masuyama, and is a 2-1-2 design, but it seems that the 2-2-1 was also made.

Edited by Peter Besenbruch, 05 December 2015 - 02:00 AM.

[Dave Mitsky]

A number of different designs share the name König.

 

Eyepieces.
Koenig designed many types of eyepieces.  The term 'Koenig eyepiece' is widely
used today but is not a precise description for a particular design.  His earlier
'Koenig eyepiece' designs included an eyepiece with a singlet eye lens & a doublet
field lens.  Most modern Koenig eyepieces are '1,2,1': a singlet eye lens, a
doublet in the middle, and a singlet field lens; but 1,1,2, and 1,2,3 eyepieces
(and other configurations) are also commonly called 'Koenigs'.  All have a wide
field of view, up to 70 degrees, with the simpler examples showing 'fuzzy edges'
in short focus telescopes.

 

http://home.europa.c...cope/koenig.txt

 

The König eyepiece shown here (many other eyepiece designs are also due to Albert König) is based on the Orthoscopic design, but splits up the three-element field lens with one extra air gap, so that it consists of a single eye lens, a two-element lens in the middle, and a single field lens. This creates an additional degree of freedom for correcting abberrations, allowing the design to be modified to provide a wider field.

 

http://www.quadibloc...ience/opt04.htm

 

Konig

 

Designed in 1915 by Albert Konig, the Konig eyepiece is similar to an Orthoscopic with a doublet field lens in place of the triplet. The original design allows for high magnification with excellent eye relief, the most eye relief proportional to focal length of any design prior to the introduction of Al Nagler's high magnification eyepieces. The Konig's apparent field of view is about 55-degrees.

Modern versions of Konigs usually use lower dispersion glasses than were available to Albert during WW I and sometimes add more elements. The most common change is to add a positive, concave-convex element before the cemented doublet field lens, with the convex surface facing the doublet. These modernized Konigs offer 60 to 70-degree AFOV's and are usually sold under proprietary names that do not credit Konig as the original designer.

 

http://www.chuckhawk...ece_designs.htm

 

König[edit]

 

The König eyepiece has a concave-convex positive doublet and a plano-convex singlet. The strongly convex surfaces of the doublet and singlet face and (nearly) touch each other. The doublet has its concave surface facing the light source and the singlet has its almost flat (slightly convex) surface facing the eye. It was designed in 1915 by German optician Albert König (1871−1946) as a simplified Abbe[citation needed]. The design allows for high magnification with remarkably high eye relief — the highest eye relief proportional to focal length of any design before the Nagler, in 1979. The field of view of about 55° makes its performance similar to the Plössl, with the advantage of requiring one less lens.

 

Modern versions of Königs can use improved glass, or add more lenses, grouped into various combinations of doublets and singlets. The most typical adaptation is to add a positive, concave-convex simple lens before the doublet, with the concave face towards the light source and the convex surface facing the doublet. Modern improvements typically have fields of view of 60°−70°.

 

https://en.wikipedia...iece#K.C3.B6nig

 

Dave Mitsky