Doublet lens fungus treatment.

[Cluster]

(Yet) another old camera arrived today. I have a hankering to try roll film in an old and "characterful" camera.
I bought a Halina 6-4. It's a simple thing, three apertures and a fixed speed shutter of type found on a box camera.
I understand that the lens is a doublet. It seems to be uncoated but has a small amount of fungus within (well, I wanted a camera with character!).

I had understood that fungus in a lens only develops on the coating, is my understanding wrong?
It's worth trying with the fungus and may not be a spoiler, so if it's difficult to shift, or if a doublet lens is a bonded pair of elements, then I'll leave it alone.

Oh, I just read that doublets are usually cemented... easy to leave then....

 

[Nod]

Leaving the "infected" lens in sunlight (UV) will apparently kill the fungus but it won't remove the dead filaments - they'll add to the wanted character!

It's probably possible to decement the doublet, clean it thoroughly and recement it but equally probably not financially viable.

 

[droj]

Mould ('fungus') only needs a substrate, & is fairly catholic about what that substrate is. It's all around on surfaces but when they're not transparent we're much less likely to notice it.

Are you sure that its mould in your lens, and not the cement disintegrating?

The Bonding of Optical Elements: Techniques and Trouble Shooting. From Summers Optical

Manual for using structural adhesives andoptical cements for the bonding of optical elements. Covers preparation ofthe substrate, cement, optical elements, and adhesives, cementing technique,uv curing, applications, and bond failure causes and remedies. From SummersOptical.Technical help with...

www.optical-cement.com

 

[Cluster]

If it can't be cleaned off easily, it's not important for this LoFi camera. I just noticed the fine filament of curly strands when looking closely at the lens through a magnifying glass.
I took the lens out and cleaned both sides, but the filaments remain. Only afterwards, I realised that this was a two element lens and that the fungus could be between the elements.

 

[ChrisR]

... I realised that this was a two element lens and that the fungus could be between the elements.

This surprises me. I'd have thought that fungus needed some sort of access to air (and moisture) to grow, so unlikely to be between two cemented glass surfaces, unless the cement had really broken down?

 

[Cluster]

This surprises me. I'd have thought that fungus needed some sort of access to air (and moisture) to grow, so unlikely to be between two cemented glass surfaces, unless the cement had really broken down?

Yes, originally, I assumed that if it had two elements there could be an air gap between them.
It's quite difficult to see it, good light at the right angle helps. It's quite possible that it's something in the cement, I guess It could be on the back of the lens, but had resisted my initial cleaning attempts with alcohol, so appears to be untouched.

 

[dmb]

A couple of drops of household ammonia plus the same of first aid box hydrogen peroxide on a cotton bud loosens most fungus.