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How can I restore this eyepiece?

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#1 shaesavage

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Posted 09 July 2020 - 07:49 PM

I recently acquired a Seiko 60mm Kellner. The surface on the top element has a haze that is rough when I lightly run my finger nail across it. I've tried Purasol and Zeiss lens wipes but neither has worked. Any suggestions for how I can restore this? If it needs professional attention, who are the professionals? I would really like to return it to glory if possible.

 

I posted this in  the Eyepiece forum in a thread with a different topic but it got buried. I thought I would post it here to see if there are other suggestions.

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#2 KTAZ

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Posted 09 July 2020 - 08:11 PM

Give some 99% isopropyl a go with a cotton swab.



#3 photoracer18

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Posted 09 July 2020 - 09:41 PM

If alcohol does not work you need to try regent grade acetone. If there is any plastic in the eyepiece then don't use it. But its the preferred cleaning agent for really dirty and stained lenses. Asked Roland. Just be careful with it and don't use it in a small room.


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#4 RichA

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Posted 09 July 2020 - 11:27 PM

I recently acquired a Seiko 60mm Kellner. The surface on the top element has a haze that is rough when I lightly run my finger nail across it. I've tried Purasol and Zeiss lens wipes but neither has worked. Any suggestions for how I can restore this? If it needs professional attention, who are the professionals? I would really like to return it to glory if possible.

 

I posted this in  the Eyepiece forum in a thread with a different topic but it got buried. I thought I would post it here to see if there are other suggestions.

The worst case of optical contamination I've come across was some kind of old lubricant.  Even acetone wouldn't get rid of it.  So I used varsol, which worked, then acetone, then lens cleaner.  That did it.


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#5 shaesavage

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Posted 10 July 2020 - 12:04 AM

Thank you! I will see how this works. 



#6 DAVIDG

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Posted 10 July 2020 - 11:27 PM

 It looks the anti-reflective coating has failed and  the glass has become etched. If so your going to have to repolish the surface using a pitch  lap and optical polish to restore the optical surface. I have done this many times. Here is  a picture of  a small pitch lap that I used to restore the optical polish on  a pair of WWII vintage binoculars  I recently restored. The lens on the left has been repolished and you can see a clear and scatter free reflection of the light in the surface. The one on the right has not and you can see all the scatter from the rough and sleeked surface of the glass.

 

                       - Dave  

 

 

pitchlap lens.jpg

polished and sleeked lenses.jpg


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#7 shaesavage

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Posted 10 July 2020 - 11:49 PM

Interesting, I will have to read more about this process. 



#8 Alrakis

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Posted 16 July 2020 - 11:52 AM

If you find out you need to polish the lens see here :

 

http://whatsouttonig...lescopekit.html

 

I followed the directions for this kit and built a singlet refractor with two eyepieces. It should give you an idea of how to proceed.

 

Chris 



#9 clamchip

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Posted 16 July 2020 - 08:19 PM

Removing damaged coatings, scroll down to 3B5:

https://maritime.org...pe/chap3.htm#3A

Dave, what do you think of this method?

 

Robert



#10 DAVIDG

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Posted 16 July 2020 - 08:55 PM

Removing damaged coatings, scroll down to 3B5:

https://maritime.org...pe/chap3.htm#3A

Dave, what do you think of this method?

 

Robert

 I have discussed hot sulfuric acid before along with critic acid and oxalic acid as other  methods to remove MgF2 coatings. Removing  just the coating when just the MgF2 coating is damaged  is fine but it won't fix the surface of the glass if the optical polish as been damaged. That is what happened to  the front surfaces of the objectives I'm showing in the picture I posted and why I had to repolish the surface.

   The OP stated that the surface of the lens in the eyepiece is rough. That indicates to me that the surface as been damaged so that is why I said that it would most likely need to be repolished to repair it. 

  Certain acids will remove MgF2 but you need to be sure what the glass type is. If it is crown like BK7 acid won't damage the glass but flint and exotic type glasses will become etched in acids.

 

             - Dave 



#11 RichA

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Posted 16 July 2020 - 08:57 PM

 It looks the anti-reflective coating has failed and  the glass has become etched. If so your going to have to repolish the surface using a pitch  lap and optical polish to restore the optical surface. I have done this many times. Here is  a picture of  a small pitch lap that I used to restore the optical polish on  a pair of WWII vintage binoculars  I recently restored. The lens on the left has been repolished and you can see a clear and scatter free reflection of the light in the surface. The one on the right has not and you can see all the scatter from the rough and sleeked surface of the glass.

 

                       - Dave  

 

 

attachicon.gifpitchlap lens.jpg

attachicon.gifpolished and sleeked lenses.jpg

i had a Celestron 40mm finder with that kind of glass issue.  You can clean it a bit, but unless you want to repolish, it's as it will be for good.




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