Fungus?

[JPD]

Yet another "is this fungus" thread.

This Retina-Xenar rear group has lots of tiny specks on the outer surface of the last element. Does it look like fungus?

I have cleaned it with 24% acetic acid, but don't want to soak it in the acid since it's a cemented pair. I'm having luck with acetic acid against a fungal infection on one of my toenails.

[Grytpype]

Can't say it looks like any fungus I've met, and I've met quite a lot! I use acetic acid in the form of ordinary malt vinegar, and it always shifts fungus in seconds.

When you say it is on the outer surface of the last element, do you mean facing the film? The white spots look out of focus compared to the specks of dust. Could the spots be at the front, facing the diaphragm?

Steve.

[JPD]

It's the side facing the film. The lens group was removed from the camera when I took the picture, so I probably turned the wrong side to the camera. Here's a better picture.

[Brian Sweeney]

It could be- I use ammonia based eyeglass cleaner with good results.

[Grytpype]

I'm sure if it was fungus, vinegar (or your 'medicinal' acetic acid) should shift it. Have you tried solvents (e.g. lighter fuel)? On at least one occasion I have successfully removed marks that resisted all other methods using cellulose paint thinners, with no ill effect on the lens or coating.

[fidget]

It doesn't look like the fungus that I have cleaned off several lenses, that had soft edges to the blobs and the odd strand running out from some. You are right to be cautious about dunking the lens, I once did and ruined a cemented lens pair.

[JPD]

Originally Posted by Grytpype

I'm sure if it was fungus, vinegar (or your 'medicinal' acetic acid) should shift it. Have you tried solvents (e.g. lighter fuel)? On at least one occasion I have successfully removed marks that resisted all other methods using cellulose paint thinners, with no ill effect on the lens or coating.

Yes, acetic acid is very effective against fungus. The doctors say that it doesn't work on nail fungus if the whole nail is infected down to the root. I've been treating it for a year, and now a healthy nail is growing out. The alternative was strong antifungal medicine that can affect the liver.

Good idea, I will try heptane. I had good luck with it before when isopropanol didn't clean the glass properly.

Originally Posted by fidget

It doesn't look like the fungus that I have cleaned off several lenses, that had soft edges to the blobs and the odd strand running out from some. You are right to be cautious about dunking the lens, I once did and ruined a cemented lens pair.

The camera (IB) seems to have been stored in a damp place for a while, since I found small corrosion marks on a steel ring (that transfer the aperture settings to the numbered scale).An earlier owner had tried to "repair" the shutter with too much oil and used grease even on the shutter retaining ring.The shutter didn't work, and focus was off. I already have Retinas of this type, but it's fun to try to get non-working ones into shape.

[JPD]

Heptane didn't work. The specks are etched in the glass. I will test this Retina and another with a perfect Xenar and compare the results later. It's been around -30ºC (-22ºF) for two weeks now.

[fidget]

Originally Posted by JPD

........... It's been around -30ºC (-22ºF) for two weeks now.

Brrrr! It makes national news here when it touches -15ºC and much of the country stops. Good luck with the lens!