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Donyet
Tinkerer
Username: Donyet
Post Number: 45
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 08, 2010 - 04:21 pm: | 
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Hello Everyone,
I recently bought a Diichi Zenobia 4.5x6 medium format folder. I cleaned it inside and out, including all the lenses. On one of the inner lenses I noticed what looks like some etching on the element, possibly from a past fungal infection. It does not look like there is active fungus, just the etching. I have not run a roll through it yet as I just got it so I don't know if it will affect the image.
For future reference, is there a way to gently polish the surface of a glass lens?
Thanks,
Alex |
Foto_gaga
Tinkerer
Username: Foto_gaga
Post Number: 32
Registered: 02-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 08, 2010 - 06:09 pm: |
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I heard soaking it overnight in hydrogen peroxide will help but I have not tried it yet. I have a lens like that from a Yashica TLR and the coating or, maybe, glass itself is sort of etched also. |
Glenn
Tinkerer
Username: Glenn
Post Number: 820
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 09, 2010 - 06:07 pm: |
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Soaking in peroxide or ammonia will 'kill' the fungus but will do nothing for the etching seen on the coating/glass. If the etching is limited to any coating present, the coating can be removed by polishing with a proper optical polish or tooth paste - if the actual glass surface is damaged then it is doubtful that DIY will correct this without damaging the optical properties. Very small deep patches of etching are best dealt with by filling in with black paint if the damage causes flare. |
Donyet
Tinkerer
Username: Donyet
Post Number: 47
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 10, 2010 - 06:11 pm: |
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Toothpaste, that's interesting. How would I go about using toothpaste without harming the lens?
I will wait and see if I get any artifacts in the images before resorting to that. I may just have to avoid shooting towards bright light with this camera.
Thanks for the tips. |
Glenn
Tinkerer
Username: Glenn
Post Number: 823
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 11, 2010 - 02:11 am: |
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Look in the Archive. |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 197
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 25, 2010 - 10:57 am: |
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1. Etching by fungus is smaller than any damage you will do using home methods of polishing glass. To visualize it, draw yourself an imaginary cross-section of a lens with a dent etched into it. Now think, how much material do you need to remove, to "clear" this dent. To really clear the etching, you would need to remove the depth of the etching uniformly from whole lens surface - thing impossible without a specialized tool.
2) Any etching, as long, as its small (not as to the area infected, but as to the area actually etched - think a spider web, it covers huge area, but the lines are actually very thin and won't stop wind), will only affect contrast of the image. This influence will not be noticeable, unless the etching renders the lens visibly opaque to the eye.
3) if the etching is heavy, but limited in area to a part of the lens only, consider masking it with black matte (flat) paint.
I consider all attempts to polish the etching off effectively good only to cheat someone into buying a bad lens, even if I can fully understand the wish to have a spotlessly shining glass in my collection myself 
Greets!
Marek |
Donyet
Tinkerer
Username: Donyet
Post Number: 48
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 16, 2010 - 03:33 pm: |
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Well the pics I got from the camera turned out fine, so I was worrying about nothing. I think as long as I don't point it towards the sun I should be fine.
It's an interesting little camera and am glad I bought it. |
Janierik
Tinkerer
Username: Janierik
Post Number: 2
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 11, 2011 - 12:05 am: |
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Hi!
I have tried lens polishing using a professional, both in cases where there was fungus etching a glass and/or scratches in the lens. I took the lenses to a professional and the results were very good. He said it was not a problem removing the scratches etc. so that the dimensions of the lenses (old tessars) was still within the original tolerances. I also recemented one doublet that had both scratches and separation and it worked out fine too. |
