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Mystery thread

05/04/2022 12:05 PM

Trying to identify the thread on a microscope eyepiece, it has no makers or other marks on it. The outside diameter of the male thread measures 26.7mm or 1.050 inches. The pitch is not easy to measure but looks like 0.5mm or about 50 tpi.

Standard lens type threads are M25 or M26 or SM1 (26.3mm, 1.035”) so it does not seem to fit with those.

Has anyone come across this size before?

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#1

Re: Mystery thread

05/04/2022 1:28 PM
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#2
In reply to #1

Re: Mystery thread

05/04/2022 1:45 PM
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#4
In reply to #2

Re: Mystery thread

05/04/2022 9:18 PM

Could be a camera lens maybe....?

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#6
In reply to #2

Re: Mystery thread

05/05/2022 4:24 AM

That 2nd link is a great site, thanks for that. Possibly matching with M27 but with a very fine pitch.

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#5
In reply to #1

Re: Mystery thread

05/05/2022 4:19 AM

The eyepiece is from a very old travelling microscope. The company have probably been using it for 25 years, no makers mark on it.

I managed to find the site in your first link yesterday but they don't show anything that matches.

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#9
In reply to #5

Re: Mystery thread

05/05/2022 4:54 AM

Could be a one-off...it seems very unusual that there is no identifying numbers, no model no brand name no serial number nothing, if I were to guess I would say it's a custom made one-off possibly special purpose microscope...What is your purpose for knowing the thread? ...are you shopping for different lenses? You might be able to find a microscope guru that could tell you something...

https://www.olympus-lifescience.com/en/microscope-resource/primer/anatomy/oculars/

https://www.microscopeworld.com/?gclid=CjwKCAjw682TBhATEiwA9crl32eDa_Kg_jhMsEOWru_NqZkU63Dxd85-kXL4H8cka0ljmwOAqNxtlBoCLFcQAvD_BwE

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#3

Re: Mystery thread

05/04/2022 6:13 PM

Please clarify:

A) I have a microscope, looking for an eyepiece.

B) I have an eyepiece, looking for a microscope.

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#7
In reply to #3

Re: Mystery thread

05/05/2022 4:33 AM

I have a lens & an eyepiece, looking to construct a simple microscope to be used on an optical rail in one of our darkrooms to view the output of our image intensifiers to check for blemishes etc.

The image shows an assembly modelled with stock parts from Thorlabs, I have also asked them if they know the thread. The eyepiece is the R.H. end part with the blue centre. Ultimately, what I need is an adaptor to fit the eyepiece thread to the standard SM1 thread in the Thorlabs part.

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#8

Re: Mystery thread

05/05/2022 4:52 AM

Additional info. It seems that M27x0.5 is a standard lens filter thread so I will explore that further.

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#10

Re: Mystery thread

05/05/2022 5:14 AM

I think I've found it, M27x0.5 to SM1 lens adaptor. Thanks for everyone's input.

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#11
In reply to #10

Re: Mystery thread

05/05/2022 7:13 AM
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#12

Re: Mystery thread

05/05/2022 7:36 AM

Why not use a cheap thread gauge like this to be sure

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#13
In reply to #12

Re: Mystery thread

05/05/2022 8:03 AM

I have the gauge but it's a very short run of thread, maybe 2.5mm. As posted earlier I'm reasonably sure that it is M27x0.5 as that seems to be a standard lens filter thread. The adaptor to fit is cheap enough so we'll get one to be certain.

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#14
In reply to #13

Re: Mystery thread

05/07/2022 12:58 AM

If the thread run is only 2.5mm, that's only 5 threads. With such a short run, the pitch could be off by a fair amount and still work, unless it is a very tight fit.

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#15
In reply to #14

Re: Mystery thread

05/09/2022 4:17 AM

Yes, agreed, especially as there is an undercut as well so probably less than 2mm of thread.

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