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Why 0.965”

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#51 Michael Covington

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Posted 10 February 2020 - 10:45 PM

That is a real possibility -- that it was an "inch" other than the one we know and love.  


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#52 GalaxyPiper

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Posted 10 February 2020 - 11:39 PM

You know, there are other items to think about, like the brass section of bands. Plenty of different size tubing and mouth pieces that come off of horns, tubas, etc...
Maybe someone got tired of blowing through theirs, and started looking through them.

 

Telescope making has been around since the Spanish conquistadors.. The military wanted spy glass telescopes on their ships to see what flags were flying on the high seas, an early friend or foe device.
Glass blowers use metal tubes to blow glass, and that has been around since ancient Egypt and Greece.

 

Someone could make career out of tracing back the history of telescopes, to various manufacturers, like the clock makers of the day back in the 1800's...
The Industrial revolution exploded with Railways, and steam powered everything. It really was a steam punk era!

 

Needs more research...for someone.

 

P.S. Measurements were taken off of the feet of kings, in the early days of serfdom, every country had their own standard of measurements for this reason. Just like language and money, and laws....
Royalty set the standard for which all their subjects followed.


Edited by GalaxyPiper, 11 February 2020 - 12:23 AM.


#53 Kokatha man

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Posted 11 February 2020 - 02:31 AM

At the risk of sounding like an echo I'll repeat the link I gave in Post #47 to this youtube video: "The manufacture of high-precision brass telescope tubes 1780 to 1990" which is an important video on the manufacture of brass telescope tube from an historical fabrication technique perspective using the old drawplate* technique: https://www.youtube....v=rf93q626KhQ  

        

*Drawing tube via drawplates (mandrels & collars) is older than "cold extrusion" tube production & almost certainly the progenitor of early eyepieces made alongside the rest of the components in nearly all old telescopes/manufacturing firms: this would include the ep barrels & spacers etc along with their lenses also...    

 

Dependant upon the mandrels & drawplates/collars which were custom-made, it is no wonder that many sizes evolved...the "Scientific Instrument Society" bulletin lists a Cassegrain/Gregorian by "J. VAN DER BILDT

FRANEKER" circa 1760 having 2 Huygens ep's...one length 47mm, diameter 27mm...& another length 95mm, diameter 26mm..!

 

My take after wading through "reams of screens" (pardon my alliteration wink.gif ) is that somewhere, someone or firm, gained a strong marketing foothold with their particular product, particularly their eyepieces & barrel sizing (which they would obviously standardise for cost etc) & this became an "industry standard" just as others "industry standards" were & are commonly adopted in manifold products.

 

I also strongly suspect that this would have preceded extruded tubing for ep barrels for the simple reason that sizing & subsequent machining/lathing was not only much later (technologically-speaking) but would have inevitably followed the drawn-tubing techniques of which the old film in the youtube video shows an example of a marvellous artisan using old equipment to create high-quality ota's...which compared to ep barrels is only a difference in scale: casting barrels & machining them would be extremely unlikely imo btw. wink.gif

 

Unless a "smoking gun" can be evinced I think this theory is as good as anything else being posited imho - but any further investigations will not include myself as I have more important things to pursue..! lol.gif  

 

The old film in the video took me back to my own jeweller's days where - besides using commercial tools for wire & tubing - I constructed hinged drawplates made from hardwood blocks to pull woven chains & endless bracelets into standardised, tight weaves such as in the top image in the "ART GALLERY" page of our website link in my signature... 


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#54 Senex Bibax

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Posted 11 February 2020 - 07:34 AM

There is even an officially defined "metric inch" that is .4 mm shorter than an Imperial inch.

 

 

That is a real possibility -- that it was an "inch" other than the one we know and love.  


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#55 clamchip

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Posted 11 February 2020 - 10:43 AM

I was talking to Frenchie and she said at home in the family business they cut corks to a

maximum diameter of 24.5mm.

For the standard 3/4 inch wine bottle neck.

The cylindrical punch cutters are then replaced. 

Don't know if this helps.

"Did the telescope eyepiece come from wine cork cutters? " nurse Mendy is wondering.

Robert

 

post-50896-0-27212100-1520809126_thumb.jpg


Edited by clamchip, 11 February 2020 - 10:49 AM.

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#56 Terra Nova

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Posted 11 February 2020 - 10:53 AM

I was talking to Frenchie and she said at home in the family business they cut corks to a

maximum diameter of 24.5mm.

For the standard 3/4 inch wine bottle neck.

The cylindrical punch cutters are then replaced. 

Don't know if this helps.

"Did the telescope eyepiece come from wine cork cutters? " nurse Mendy is wondering.

Robert

 

attachicon.gifpost-50896-0-27212100-1520809126_thumb.jpg

Sure does help Robert! It remind me that this problem will only be solved after a good bottle or Merlot!


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#57 Ben H

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Posted 11 February 2020 - 03:10 PM

Found a helpful PDF on the Thuringian state website documenting the conversions from the various historical measures in use before Germany adopted the metric system

 

https://www.thuering...torien/ih_7.pdf

 

According to the document, for measures of length Jena followed the Weimar standard (282 cm / Fuß), or 23.5 mm / zoll. All told, 13 different cities were following the Weimar standards, out of 47 cities following another city's standards. That would seem to indicate the Weimar standard was rather popular in Thuringia at the time. 

 

Unhelpfully, I can't figure out how a machinist would get from 23.5 mm to 24.511 mm.

So maybe a red herring. 



#58 DAVIDG

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Posted 11 February 2020 - 03:58 PM

 I throw out another guess based on optics. Eyepieces comes in a range of focal lengths. The magnification and field of view are determined by  the focal length,  and the configuration of those lenses. One of the properties of the configuration is the diameter of the lens. Your  not going to make a low  power wide field eyepiece with small diameter lenses. So the 24.5mm barrel size might have been chosen to allow for lenses  of the correct focal length and diameter to allow the for the lowest power widest field of view  eyepiece that was  chosen for that time.  

   If you use the full moon which is 0.5° in diameter as a standard as the object you wish to completely view in an eyepiece  and  then look  at the focal length for  a typical refractor being produced at the time when the 24.5mm eyepiece started to show up, what diameter and focal length lens does one need to produce a field of view to 0.5° or more. 

 

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#59 Ben H

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Posted 11 February 2020 - 04:04 PM

 what diameter and focal length lens does one need to produce a field of view to 0.5° or more. 

 

                    - Dave 

You are probably better qualified to answer that than most here lol.gif



#60 GalaxyPiper

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Posted 31 March 2020 - 07:06 PM

You know, it is moments like these that we live in such an incredible age of discovery and technology that a mere virus can lay waste to a civilization.

So my thoughts naturally gravitate to why people hoard toilette paper, like they want to be the last people on earth to clean themselves.

 

Which brings me to another thought, and this thread, so bear with me for a moment. Toilette paper was invented in 1857...163 years ago.

 

http://www.whoinvent...d-toilet-paper/

 

What people were using before then can be eluded to. Maybe one reason my Great grandfather had a 500 acre corn farm in Virginia.

But I digress. It can be said that the best room in the house, to be left alone to ones thoughts, is the bathroom, W.C. etc...

 

Modern "Rolled" toilette paper didn't come about until 1883, before then they were just flat sheets.

 

il_570xN.1522088953_mm7r.jpg

etsy.com

 

Toilette paper on a roll didn't come out in wide use until then, but was not splinter free until 1930

 

Patent_465.588%2C_S._Wheeler%2C_Toilet_P

https://commons.wiki...c._22,_1891.jpg

 

But here again, I need to focus no the subject at hand.

And that is the modern telescoping toilette paper roll holder.

 

When this was invented is unknown at this time, as many fixture's arose like so many other ideas that piggyback on another, I can only imagine that if Carl Zuiss was contemplating his next move, as it were, he might have had to change out a roll, and upon examining the telescoping device, found a solution to a problem.

 

I took out my silvered plastic toilette holder and measured it with my digital calipers. The outside sleeve measures .973" and the inner tube measures .857".

The inner tube is obviously too small to be of use, but not the outer one.

 

If he had come across a brass version of said toilette holder, a known quantity, he might have asked for a quantity of the tubing to be used.

This of course is all speculation, but could have been another avenue of invention.


Edited by GalaxyPiper, 01 April 2020 - 02:25 PM.

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#61 jsiska

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Posted 31 March 2020 - 07:40 PM

Long ago, before anyone can remember, before history even, an obscure glass maker invented the telescope. It didn’t work; he needed to make an eyepiece. So he made the very first eyepiece for his newly invented telescope. He made the eyepiece 0.75 inch diameter. That was a very long time ago. Since then, the universe has stretched. Every galaxy and all to way down to the sub atomic particles and even every quark got further apart. With a modern ruler, that 0.75 inch diameter eyepiece now  measures a wopping 0.965 inch in diameter.


Edited by jsiska, 31 March 2020 - 08:00 PM.

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#62 Kokatha man

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Posted 31 March 2020 - 07:57 PM

 

Which brings me to another thought, and this thread, so bear with me for a moment. Toilette paper was invented in 1857...163 years ago.

 

http://www.whoinvent...d-toilet-paper/

 

 

etsy.com

 

Toilette paper on a roll didn't come out in wide use until then, but was not splint free until 1930

 

 

https://commons.wiki...c._22,_1891.jpg

 

But here again, I need to focus no the subject at hand.

And that is the modern telescoping toilette paper roll holder.

 

When this was invented is unknown at this time, as many fixture's arose like so many other ideas that piggyback on another, I can only imagine that if Carl Zuiss was contemplating he next move, as it were, he might have had to change out a roll, and upon examining the telescoping device, found a solution to a problem.

 

 

Crikey Piper! - I have to say that website about the invention of toilet paper seems pretty suss as far as objective accuracy is concerned for me...but "splint free" (presuming it contained no nasty little splinters) sounds downright horrid to me..! bigshock.gif step.gif

 

Perhaps (if Joe Gayetty really did invent it) that is why he took 63 years from 1857 before Quote: <"this toilet paper was made available to people in 1920">

 

Also, the link to Seth Wheeler seems to suggest there was some sort of dispute about who invented it - or did Joe & Seth fight over toilet paper back then, like they are doing in supermarkets today..?!?

 

Forget Carl "Zuiss".....this sounds more like Dr. Seuss having one of those movements, err I mean moments idea.gif on the john to come up with that focuser dimension idea... looney.sml.gif

 

Lastly (& with only gentle humour in all of this) I'm very reluctant to click that light bulb in the S. Wheeler link on toilet paper to find out more <"about reusing"> bigshock.gif  


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#63 GalaxyPiper

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Posted 31 March 2020 - 08:32 PM

Crikey Piper! - I have to say that website about the invention of toilet paper seems pretty suss as far as objective accuracy is concerned for me...but "splint free" (presuming it contained no nasty little splinters) sounds downright horrid to me..! bigshock.gif step.gif

 

Perhaps (if Joe Gayetty really did invent it) that is why he took 63 years from 1857 before Quote: <"this toilet paper was made available to people in 1920">

 

Also, the link to Seth Wheeler seems to suggest there was some sort of dispute about who invented it - or did Joe & Seth fight over toilet paper back then, like they are doing in supermarkets today..?!?

 

Forget Carl "Zuiss".....this sounds more like Dr. Seuss having one of those movements, err I mean moments idea.gif on the john to come up with that focuser dimension idea... looney.sml.gif

 

Lastly (& with only gentle humour in all of this) I'm very reluctant to click that light bulb in the S. Wheeler link on toilet paper to find out more <"about reusing"> bigshock.gif  

From what I gather, Joe Gayetty invented sheets of paper as toilette paper that also had aloe vera gel in it. It wasn't until 1920 that toilet paper was widely used on a roll, and didn't become splinter free until 1930.

I think it is Iconic that "Wheeler" invented the perforated roll of T.P., just like "Crapper" invented the flush toilet.


Edited by GalaxyPiper, 31 March 2020 - 09:38 PM.

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#64 CharlieB

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Posted 31 March 2020 - 09:50 PM

Let's please keep on topic, folks.


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#65 Exnihilo

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Posted 31 March 2020 - 11:02 PM

If I once new the answer to this question, I have forgotten it in my acknowledged period of dotage. How did the obtuse 0.965” or 24.5 mm standard ever come about for eyepieces? If it started in a Metric System country why didn’t they just choose 25mm? If it started in an English System country, why not just 1.00 inches? Did no one like round numbers when they picked a standard? It just seems weird to me!

Lol, well the ex-software developer in me has a strong belief that any software bug can be fixed by imagining the stupidest thing possible must be the cause.  So, as stupid as it sounds, its fairly likely that someone confused 24.5 with 25.4.  I know this has been proposed before, but the software debugger in me says this is the most likely scenario!


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#66 luxo II

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Posted 01 April 2020 - 02:35 AM

Well, ponder this:

 

24.5/25.4 = 0.9646.

 

IMHO someone with metric tools thought 1" was 24.5mm (ie transposed the 4 and 5). And the mistake has stuck, ever since. 


Edited by luxo II, 01 April 2020 - 02:35 AM.

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#67 Kokatha man

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Posted 01 April 2020 - 03:45 AM

Well luxo - I don't think anyone disputes the fact that 24.5 ÷ 25.4 = ♎ 0.965 - that's the whole point of the debate, why they chose 24.5mm...or the Imperial measurement of 0.965 inches... wink.gif

 

The question still remains as to why whoever came up with this slightly odd measurement that became the standard arrives at such a figure - if it was someone from a country using the Metric System the question is still the same, why 24.5mm instead of 25mm.....just as it is if it was someone using the Imperial System...ie, why not 1.0" instead of 0.965"..?

 

Of course if either system user had first come up with 1.0" or 25mm but the popularity/common usage was something adopted by users from the different measurement system then that transposition of figures that Exnihilo & others such as yourself suggest becomes quite plausible in a to & fro error compilation...a sort of Chinese Whisper or dyslexic interpretation!


Edited by Kokatha man, 01 April 2020 - 03:45 AM.

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#68 Kokatha man

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Posted 01 April 2020 - 05:11 AM

Another prospect which I can't recall being investigated is that these ep dimensions follow on from those of the telescopes in use in maritime sextants: possible to consider these instruments as forerunners of telescope standards where Wiki states of half & whole-horizon sextants that: <"In both types, larger mirrors give a larger field of view, and thus make it easier to find a celestial object. Modern sextants often have 5 cm or larger mirrors, while 19th-century sextants rarely had a mirror larger than 2.5 cm (one inch). In large part, this is because precision flat mirrors have grown less expensive to manufacture and to silver.">

 

The telescope component of these sextants would then likely be of a similar dimension...& then possible corruptions as suggested by many here might (or might not!) have resulted in that 24.5mm or 0.965". :)


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#69 luxo II

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Posted 01 April 2020 - 05:29 AM

Kokatha, maybe I didn't quite put it completely. 

 

Scenario:

 

19th century, young pommy glass-pusher accustomed to IMPERIAL measurements happens to have a METRIC lathe from one of those nasty European countries... (probably the froggies or the Boche). But he's not accustomed to metric conversions, and he's not too good at arithmetic either - if he was he'd have got a proper job as an accountant or at a bank.

 

This is the pre-calculator era, when one used slide rules or log tables - or did arithmetic the hard way with pencil and paper.

 

So he thinks 1" sounds nice, but in converting it to metric measurements on the lathe, transposed the 4 and 5 in his head, by mistake, and didn't check. 

 

And in doing so set a precedent that unfortunately stuck, quite possibly because his eyepieces were good enough to be popular - to the extent telescope makers realised they had better make draw tubes to suit.

 

I'm sure we've all had "blonde moments".

 

And just for Terra, pardon me for assuming it was a "he"... I doubt ladies would have been making this sort of thing 100-150 years ago...


Edited by luxo II, 01 April 2020 - 05:43 AM.

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#70 Kokatha man

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Posted 01 April 2020 - 07:44 AM

Hi luxo - I understood completely your hypothesis, Exnihilo put exactly the same scenario of this "dyslexic transposition" as I humorously labelled it above without your embellishments re an Imperial creator utilising a European/metric lathe...or vice-versa lol.gif - as I believe others have expounded similarly in this thread...this leaving aside the question as to whether a lathe or more possibly the craft of drawing tubing such as demonstrated in the link I provided in Post #53 was an alternative method of tube-manufacture. (as it most certainly was for early instruments...)

 

Whatever, as maritime sextants were generally an older use of telescopic elements & probably more common I tend to lean towards their manufacture being a more likely starting point for the (possibly more original) 1" or 25mm "standard" - with the scenario of confusing 25.4 & 24.5 a possible additional factor...but whatever theories we each advance I'm personally still awaiting something a bit more definitive..! lol.gif


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#71 oldscope

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Posted 05 April 2020 - 10:40 PM

I'm not even sure the 24.5mm barrel diameter was considered any sort of standard before it was adopted by the Japanese. I know Zeiss used it as their own standard, but I don't know if any other German brands used it before WW2. I know Kosmos (supplied by first Merz, later by Wachter and Lichtenknecker) used 31mm diameter eyepieces (NOT 31.7mm/1.25"!) for a very long time, well into the 1970'ies, possibly later. They still list them in a catalogue from 1980. Steinheil used a propietary thread diameter and according to their 1907 catalogue, all their eyepieces for their own telescopes are thread-on only, although some of the eyepieces could be made with a push-fit barrel to fit the "popular size", but what size that is, is not specified!   

 

To summarize: We know that Zeiss used the 24.5mm barrel and that the Japanese adopted it, possibly before WW2, but certainly after, and it became popular once cheap Japanese scopes flooded the market.

 

Other than that, we know very little with any degree of certainty.

 

 

Clear skies!
Thomas, Denmark 

Actually there are quite a few things we know for certain about the history of eyepiece sizes. In the U.S., the earliest commercial telescope maker, Henry Fitz, started the game with 1.29 American inch diameter eyepieces. Next up was Alvan Clark, who (for **** and giggles) decided to be different and downsized to 1-1/8 inch barrels. Those were the two important makers at the time in the U.S. Then after the Civil War, John Byrne, Fitz' protege continued what he knew and kept up with 1.29" eyepieces. So did Wm. Mogey, copying his New York brethren. Enter Uncle John Brashear out in Western Pennsylvania. The telescope he was familiar with, and the eyepieces it had, were by Fitz. So he started copying the same diameter, like the others, at 1.29" barrel diam. But ... and here's where it gets good. Brashear was a man with real machinist and engineering background and he switched to a more 'even' size of 1-1/4", ie. 1.25 rather than the odd-ball 1.29 inch. Note that pipe sizes were becoming standard in the plumbing industry by then (and as an example, kitchen sink drain-pipe was also standardized at 1.25" ... so there was a big, ready supply of brass and copper pipe around in that diameter, while 1.29" would need to be hand made.) Brashear, being the engineer that he was (he was the President of the Am. Soc. of Mech. Engineers, for example) was all for standardization and wrote a paper imploring scientists and astronomers to embrace the concept. Well, eventually all of the American telescope makers (Saegmuller; Warner & Swasey; Lohmann; Gaertner, and eventually also Mogey fell in line and switched to the 1-1/4 inch standard and we still have it today.

 

Regarding the Zeiss (and then Japanese) size, I suspect that it has its origins in the microscope business, which is where Zeiss began. But I am not a microscope collector, so someone else might weigh in on that theory. Of course it went over to Japan between the wars during a significant transfer of technology. War makes for strange bed-fellows.

 

Why does Dan have some Zeiss-sized Brashear eyepieces? Because Brashear would make any custom thing for anyone who wanted it. Maybe the reflector owner also had a Zeiss traveler? Maybe they fit some accessory made by Zeiss? But it was not a standard size for Brashear. We have his catalogs and it does not show up. And of the hundred or so Brashear eyepieces I've seen, the only small ones are for Vernier viewing or micrometers, etc.

 

Cheers,

 

Bart F.


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#72 Astrojensen

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Posted 06 April 2020 - 01:50 AM

 

Regarding the Zeiss (and then Japanese) size, I suspect that it has its origins in the microscope business, which is where Zeiss began.

No, that theory doesn't hold water, either, I'm afraid. Zeiss was making microscopes with the standard 23.2mm eyepiece barrel long before they began making telescopes. 

 

 

Clear skies!
Thomas, Denmark


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#73 Terra Nova

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Posted 09 April 2020 - 08:55 AM

No, that theory doesn't hold water, either, I'm afraid. Zeiss was making microscopes with the standard 23.2mm eyepiece barrel long before they began making telescopes. 

 

 

Clear skies!
Thomas, Denmark

True and anyone who has adapted microscope eyepieces for use in 0.965” telescopes knows that there is a substantial difference between 23.2mm and 24.5mm.


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#74 oldscope

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Posted 11 April 2020 - 09:57 PM

True and anyone who has adapted microscope eyepieces for use in 0.965” telescopes knows that there is a substantial difference between 23.2mm and 24.5mm.

Maybe the Zeiss guys threw darts to pick a size? Probably not. Or they were drunk when they set up the lathes? Doubtful too. Maybe some other company in Deutschland used that size prior and Zeiss, a relative late-comer to the telescope game, threw in with them? Could be ... it's a good topic for a history of science PhD. thesis. graduate.sml.gif

 

Bart


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#75 Astrojensen

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Posted 12 April 2020 - 01:57 AM

Maybe the Zeiss guys threw darts to pick a size? Probably not. Or they were drunk when they set up the lathes? Doubtful too. Maybe some other company in Deutschland used that size prior and Zeiss, a relative late-comer to the telescope game, threw in with them? Could be ... it's a good topic for a history of science PhD. thesis. graduate.sml.gif

 

Bart

That is a real possibility and the theory I'm currently leaning towards, but, alas, we have no proof. 

 

 

Clear skies!

Thomas, Denmark




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