Delamination/fungus on lens filter


May 6, 2013
90
0
6
23
Singapore
#1
Hi guys, I have a very old B+W filter skylight vertuget coated, which I'm using on my helios 44m. The filter is clear and looks fungus free under normal conditions and sunlight, but when I put it in a air-conditioned room... weird marking on the filter (it looks like fungus) start to form. It's probably due to condensation/moisture after removing it from the room. I can easily wipe the fungus-like markings away with a cloth and the filter looks normal again. :confused:
I checked online and it may be delamitation where the lens coating is damaged.
Anyone can help me on this? Is it fungus and will it spread to my current lens or the other lenses in my dry cabi?

Thank you.
 

Edwin Francis

Senior Member
Mar 24, 2006
883
3
18
www.sgwriter.com
#2
If your coating is damaged you should be able to see in in good light -- just look at the surface at an angle, move it about a little. If the fungus has eaten away part of the coating it should be obvious. If you managed to just wipe it clean (we used to use a mild abrasive suspension for stubborn fungus), then you will probably be fine. Just check the same spot now and then to ensure all is well.

I wouldn't put badly contaminated lenses together with nice clean ones, but if you've already cleaned it off, you won't really be spreading anything. Fungal spores are all around us, including inside your lenses, right now. They just need the right conditions to grow i.e. dark and moist. So store your lenses well :)
 

catchlights

Moderator
Staff member
Sep 27, 2004
21,903
46
48
Punggol, Singapore
www.foto-u.com
#3
May 6, 2013
90
0
6
23
Singapore
#4
If your coating is damaged you should be able to see in in good light -- just look at the surface at an angle, move it about a little. If the fungus has eaten away part of the coating it should be obvious. If you managed to just wipe it clean (we used to use a mild abrasive suspension for stubborn fungus), then you will probably be fine. Just check the same spot now and then to ensure all is well.

I wouldn't put badly contaminated lenses together with nice clean ones, but if you've already cleaned it off, you won't really be spreading anything. Fungal spores are all around us, including inside your lenses, right now. They just need the right conditions to grow i.e. dark and moist. So store your lenses well :)
I checked but under sunlight I can't see anything, the filter is clear. The weird fungi like patterns only appear when there's condensation after putting it in a cold room. You know why it happens?
Yep, I can clean the patterns off after that.
 

Edwin Francis

Senior Member
Mar 24, 2006
883
3
18
www.sgwriter.com
#5
Possibly very minor damage to coating.

But what you're saying sounds a little odd -- if condensation shows the coating damage, wiping it off should not make a difference i.e. exhale onto the lens, see a spiderweb pattern, wipe, then breathe it again, now pattern is gone?

Coating damage isn't fixed with just a wipe. Did I misunderstand you?
 

shierwin

Senior Member
Dec 29, 2008
3,457
10
38
East Coast
#6
When you are not happy with the filter, just replace it........
 

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