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Brass lens identification

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#1 MGAR

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Posted 05 February 2023 - 02:46 PM

Mods, feel free to move this to the appropriate forum if it doesn't fit here.

 

I was given this brass lens at a watch mart sale awhile ago. There are no markings, and it has a removable cap that looks like a sun lens (not going to test this). The lens does come into good focus when used "straight through" on my F/20 soda straw. I'd compare it to a standard 10mm FL lens based on the image circle it produces. Other than the removable cap, it's one solid piece. The only way to remove the lens would be to unscrew the inner flange.

 

Modern or vintage, any ideas of a maker? Thanks in advance! Gary

 

IMG_5428.jpg

IMG_5429.jpg

IMG_5425.jpg

 

 

 


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#2 MGAR

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Posted 05 February 2023 - 02:47 PM

Here the look of it on my soda straw.

 

IMG_5430.jpg


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#3 gstrumol

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Posted 05 February 2023 - 02:53 PM

I tried Google Lens on the picture you posted and it came up with an an eyepiece from a Bausch & Lomb compound microscope ... for what it's worth.

 

Gary


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#4 Supernova74

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Posted 05 February 2023 - 03:01 PM

I’m certain if it was an Astronomical eyepiece it wouldn’t have a thread on the bottom.I did own a w.watsons and sons of London 3.4” brass refractor and all the eyepieces if I recall was more of a push fit and a time era of 1920,s.then again I maybe wrong


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#5 MGAR

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Posted 05 February 2023 - 08:00 PM

Thanks for the replies! I'm still puzzled by the dark filter cap, which is certainly not protective from what I can see. These mystery lenses are interesting; I'll be testing this one on a clear night to see how well it does on the sky.

 

Cheers,

Gary



#6 bthrel

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Posted 05 February 2023 - 09:08 PM

Lunar filter? or is it too dark for that... nice find.



#7 RichA

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Posted 05 February 2023 - 09:27 PM

Mods, feel free to move this to the appropriate forum if it doesn't fit here.

 

I was given this brass lens at a watch mart sale awhile ago. There are no markings, and it has a removable cap that looks like a sun lens (not going to test this). The lens does come into good focus when used "straight through" on my F/20 soda straw. I'd compare it to a standard 10mm FL lens based on the image circle it produces. Other than the removable cap, it's one solid piece. The only way to remove the lens would be to unscrew the inner flange.

 

Modern or vintage, any ideas of a maker? Thanks in advance! Gary

 

attachicon.gifIMG_5428.jpg

attachicon.gifIMG_5429.jpg

attachicon.gifIMG_5425.jpg

Original brass lacquering from the late 1800's to early 1900's was very high-quality.  That's one way to tell these brass items from the contemporary Indian knock-offs we see cluttering sites like Etsy. 


Edited by RichA, 05 February 2023 - 09:28 PM.


#8 MGAR

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Posted 05 February 2023 - 11:53 PM

Lunar filter? or is it too dark for that... nice find.

Way too dark for a lunar filter, I can barely see an outline of a 60 watt bulb. Makes me think this was a sun or high optic filter of some sort. The bottom threads... could this have been part of an interchangeable telescope eyepiece set?

 

I mean could a Huygenian microscope eyepiece focus in a F/20 setup?

https://www.surpluss...tem/L1863D.html

 

Gary



#9 Ken Launie

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Posted 06 February 2023 - 12:13 AM

Mods, feel free to move this to the appropriate forum if it doesn't fit here.

 

I was given this brass lens at a watch mart sale awhile ago. There are no markings, and it has a removable cap that looks like a sun lens (not going to test this). The lens does come into good focus when used "straight through" on my F/20 soda straw. I'd compare it to a standard 10mm FL lens based on the image circle it produces. Other than the removable cap, it's one solid piece. The only way to remove the lens would be to unscrew the inner flange.

 

Modern or vintage, any ideas of a maker? Thanks in advance! Gary

 

attachicon.gifIMG_5428.jpg

attachicon.gifIMG_5429.jpg

attachicon.gifIMG_5425.jpg

Hi,

A photo showing the underside of the lens at a slight angle (basically the opposite of the first of your photos) can be informative. Also, what are the approximate dimensions, in particular the OD of the threaded section?

Regards,

--Ken



#10 MGAR

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Posted 06 February 2023 - 11:32 AM

Hi Ken,

 

Hopefully these will help. The OD of the threaded section is 31.45mm.

 

I had a pretty good lunar view last night with this lens.

 

Gary

 

IMG_5440.jpg

IMG_5442.jpg

IMG_5443.jpg


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#11 stevep

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Posted 06 February 2023 - 03:38 PM

I think it's most probably a telescope eyepiece, the thread described sounds like a R.A.S thread ''Royal Astronomical Society'' this was a common thread on older UK telescopes for many many years and was still being used right up until the 1960's by some makers,

 

Steve


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#12 Ben Bajorek

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Posted 07 February 2023 - 06:55 AM

It is a Bardou eyepiece on top of some kind of lens adaptor tube, maybe to get it to fit a R.A.S. thread.  Try and see if you can unscrew the eyepiece from the adaptor tube.  


Edited by Ben Bajorek, 07 February 2023 - 07:46 PM.

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#13 MGAR

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Posted 07 February 2023 - 10:26 PM

It is a Bardou eyepiece on top of some kind of lens adaptor tube, maybe to get it to fit a R.A.S. thread.  Try and see if you can unscrew the eyepiece from the adaptor tube.  

Thanks Ben! The adapter tube (if true) is tighter than a drum and cannot be unscrewed. I also used a PB blaster to see if that would break it, but no dice. I'll most likely leave it in its current state for now.

 

Gary


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#14 Ben Bajorek

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Posted 08 February 2023 - 06:23 AM

Thanks Ben! The adapter tube (if true) is tighter than a drum and cannot be unscrewed. I also used a PB blaster to see if that would break it, but no dice. I'll most likely leave it in its current state for now.

 

Gary

I recently unscrewed a similar stuck Bardou eyepiece from an extension tube.  I was worried the the assembly was soldered together it was so tight.  But it did unthread with the help of some lens filter type wrenches, penetrating oil and gorilla tape.  You eyepiece and lacquering are it such nice condition I would leave it.  


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