Theo Sulphate
Member
If it's possible to keep your lenses in an environment of low to moderate relative humidity (under 50%), then fungus will not grow. Above 60%, it will grow.
The sunlight-UV process has worked to de-yellow thorium element lenses; I personally don't know about its effectiveness on fungus. However, I don't like the idea of putting a lens in the sun for days or weeks (especially in the summer, since you're in Rio) because I'd be concerned about drying out the aperture and focusing helicoid lubricants.
As others have mentioned, it may not be fungus - just a fogging that can be cleaned.
The sunlight-UV process has worked to de-yellow thorium element lenses; I personally don't know about its effectiveness on fungus. However, I don't like the idea of putting a lens in the sun for days or weeks (especially in the summer, since you're in Rio) because I'd be concerned about drying out the aperture and focusing helicoid lubricants.
As others have mentioned, it may not be fungus - just a fogging that can be cleaned.