22 replies to this topic

[Dave1066]

Well as my interest has been sparked by old eyepiece design I have been doing a lot of digging and research. 

Some folks may find this useful as an eyepiece tool, it clearly states the name, year, and F ratio the eyepieces were designed to work at, although not always strictly, like ball eyepieces can work down to F10 fine.

 

 

When thinking of making my own ball eyepiece, and also making my own Dollond eyepiece. I remembered I had some Japanese eyepieces that came with my Towa in 0.965" variety. One is a symmetrical Ramsden eyepieces in 4mm, 6mm and 9mm Huygens, one is what I take to be a Kellner in 22mm ( has the designation of Ke22mm ) .

 

I also have what I think is two microscope eyepieces which are the same, which I'm not even sure who made it? It has 6X on it. The focal length of a microscope is 250mm. So 250/6= 41.66. So it would be equivalent to 41.66mm focal length eyepiece. 

 

Needless to say I have ordered a 1.25" to 0.965" Baader adapter. So I can try these old eyepieces out in all my telescopes. The glass in all eyepieces look spot on, no scratches whatsoever, and I had cleaned them years ago.

 

Below is a photo of the eyepiece, if anyone can help me identify it? 

 

Dave
 

Edited by Dave1066, 11 March 2018 - 12:20 PM.

[Pollux556]

You may dismount it and compare the lens train with the chart.  At your risk....

[Dave1066]

I've already ruled that out, which is why I am asking...I'm after the manufacturer most importantly.

Edited by Dave1066, 11 March 2018 - 01:01 PM.

[jimr2]

Thanks for your nifty chart Dave! So, one question however...what kind of eyepiece was Galileo using in his first scopes, starting in1608-09?? Always been curious about that! Thanks!

-jim-

[Astrojensen]

Thanks for your nifty chart Dave! So, one question however...what kind of eyepiece was Galileo using in his first scopes, starting in1608-09?? Always been curious about that! Thanks!

-jim-

A simple negative lens, like a barlow, but nonachromatic. The field of view is REALLY narrow! 

 

 

Clear skies!
Thomas, Denmark

[stevep]

I've already ruled that out, which is why I am asking...I'm after the manufacturer most importantly.

The eyepiece in your photo was made by Watson, difficult to tell design from just one photo,

my guess is it would be easy to disassemble to have a look 

 

Steve

[jimr2]

OK Thomas, thanks--yes, I knew that the FOV was really narrow for him...!

 

(and I take it that's what H. Lepershey (sp?) used too in his design?)

-jim-

[Joe1950]

Just a point of interest...

 

Notice on the chart the Scidmore Design.

 

In the 1960s my dad worked at the Frankford Arsenal in Philadelphia. He was a machinist and model maker. He worked closely with the optics department and knew Wright H. Scidmore, who designed that very eyepiece for the US Army.

 

This was in the 1960s. The eyepiece had an unheard of (at the time) 90° AFOV. And while not fully corrected at the shorter F ratios it was indeed ahead of its time. Closest to it was the Erfle with a 65° AFOV, itself not being orthoscopic to the edge.

 

The Scidmore did not use an integrated negative amplifier, often referred to as a Smyth lens, as is seen in most of today's wide field, shorter FL designs.

 

For whatever reason the design never made it into the commercial or amateur market. Maybe the military did not share the design or maybe the build would have been too expensive.

 

Fortunately, around 1980 the brilliant optician and entrepreneur Al Nagler revolutionized the eyepiece world with his designs and quality production standards.

Edited by Joe1950, 11 March 2018 - 06:00 PM.

[Dave1066]

The eyepiece in your photo was made by Watson, difficult to tell design from just one photo,

my guess is it would be easy to disassemble to have a look 

 

Steve

Thank you for identifying the manufacturer for me, as I have two of them, I will take one apart and see what design it actually is. 

[Dave1066]

Thanks for your nifty chart Dave! So, one question however...what kind of eyepiece was Galileo using in his first scopes, starting in1608-09?? Always been curious about that! Thanks!

-jim-

 

It's not my chart, but one I found online, I have been doing the odd search now and then to see what eyepiece charts would come up, this came up yesterday during my research. Best chart I've ever seen. 

[Dave1066]

It's not my chart, but one I found online, I have been doing the odd search now and then to see what eyepiece charts would come up, this came up yesterday during my research. Best chart I've ever seen. 

 

Thomas already answered Thanks Thomas, I didn't know, and would of had to have done some digging to find out.

[Dave1066]

Just a point of interest...

 

Notice on the chart the Scidmore Design.

 

In the 1960s my dad worked at the Frankford Arsenal in Philadelphia. He was a machinist and model maker. He worked closely with the optics department and knew Wright H. Scidmore, who designed that very eyepiece for the US Army.

 

This was in the 1960s. The eyepiece had an unheard of (at the time) 90° AFOV. And while not fully corrected at the shorter F ratios it was indeed ahead of its time. Closest to it was the Erfle with a 65° AFOV, itself not being orthoscopic to the edge.

 

The Scidmore did not use an integrated negative amplifier, often referred to as a Smyth lens, as is seen in most of today's wide field, shorter FL designs.

 

For whatever reason the design never made it into the commercial or amateur market. Maybe the military did not share the design or maybe the build would have been too expensive.

 

Fortunately, around 1980 the brilliant optician and entrepreneur Al Nagler revolutionized the eyepiece world with his designs and quality production standards.

 

Thanks for sharing the story, that's an amazing claim to fame really from an astronomy point of view! Not many people could claim there farther invented an eyepiece way ahead of its time!

[Joe1950]

Thanks Dave. My dad didn't invent the eyepiece, but worked with the gentleman who did at the Frankford Arsenal in Philadelphia, Wright H. Scidmore.

 

My dad was involved with making working models of many inventions developed at the Arsenal, most of which were classified and he couldn't talk about at the time. He was an excellent machinist and also a professional trumpet player and music arranger.

 

The history of many of the eyepiece designs is very interesting in of itself.

[Astrojensen]

OK Thomas, thanks--yes, I knew that the FOV was really narrow for him...!

 

(and I take it that's what H. Lepershey (sp?) used too in his design?)

-jim-

Yes. All the first telescopes used this design, until Kepler suggested using a biconvex lens instead. 

 

 

Clear skies!
Thomas, Denmark

[ChristianG]

Hi Dave.

 

I think Watson made mostly microscope eyepieces (it says '6X').

 

Contact these guys, maybe?

 

http://www.microscop.../iw-watson.html

 

--Christian

Edited by ChristianG, 12 March 2018 - 02:40 PM.

[Starman1]

And the 120° Kohler never made it into production, either.

Many eyepieces designed years ago never made it into production.

Here is another chart and a link:

Chart:

http://www.quadibloc...ience/opt04.htm  (go down the page slightly)

Link:

http://www.brayebroo...ofEYEPIECES.pdf

 

Also, many eyepieces have differing numbers of elements across the focal length range, like the Pentax XW, with 6, 7, and 8 elements, depending on focal length.

TeleVue Ethos is the same, as are many others.

Edited by Starman1, 12 March 2018 - 05:48 PM.

[Joe1950]

That second link is especially a treasure trove of eyepiece history, Don! I've often wondered how a Tolles worked, being a solid piece of glass!

[Dave1066]

And the 120° Kohler never made it into production, either.

Many eyepieces designed years ago never made it into production.

Here is another chart and a link:

Chart:

http://www.quadibloc...ience/opt04.htm  (go down the page slightly)

Link:

http://www.brayebroo...ofEYEPIECES.pdf

 

Also, many eyepieces have differing numbers of elements across the focal length range, like the Pentax XW, with 6, 7, and 8 elements, depending on focal length.

TeleVue Ethos is the same, as are many others.

Thanks Starman1, both links are good, I'm well acquainted with the Brayebrook observatory. I'd love to get my hand on a Tolles eyepiece to try on the planets! To see how it compares to my orthoscopic eyepieces, and Brandon eyepiece. 

[Astrojensen]

 

And the 120° Kohler never made it into production, either.

I think I recall reading somewhere that these eyepieces were designed for and used in U-boat periscopes, so they do seem to have been produced, although not in any great number. Köhler was an optician at Zeiss. Can you imagine the production price of a 120° degree, hand-made, military grade Zeiss eyepiece? 

 

 

Clear skies!
Thomas, Denmark

[Pollux556]

Köhler was an optician at Zeiss. Can you imagine the production price of a 120° degree, hand-made, military grade Zeiss eyepiece? 

 

 

Clear skies!
Thomas, Denmark

And many at the bottom of the sea 

[Starman1]

Who's to say where the design came from for the 12 element 120° Explore Scientific eyepiece?

[Astrojensen]

And many at the bottom of the sea 

I think the 120° Köhler was only developed after WW2. I've looked through the periscope of a WW2-era submarine (swedish) and the periscope eyepiece was definitely NOT a 120° design, although it was fairly wide. 

 

 

Clear skies!
Thomas, Denmark

[jimr2]

Thomas,

OK, thanks again for the info on early eyepieces!
-jim-