Verito 6 1/8 inch lens with fungus in front element

[Simon Benton]

I have obtained at a very low cost a 6 1/8 inch Verito in a barrel. The front element has fungus (reason is was so cheap) and I am wondering if this a cemented doublet or is this just a single piece of glass with a cemented doublet at the rear. I have checked using google but could not find a definitive answer. Any help/advice greatly appreciated. I assume if the front eleemnt is a single piece of glass I would be able to clean it?

[Louis Pacilla]

Hey Simon
Yes the front cell of the Verito is a single element

[Mark Sawyer]

Louis is quite right, single element at the front, cemented doublet at the rear, (which can be used as a Landscape Lens by itself). It's possible someone reversed them. I'd soak the offending element in bleach overnight, and fume the rest in a closed container above some bleach to kill any remaining fungus.

[Simon Benton]

Thank you Louis and Mark. I cleaned the back of the front element with a weak bleach solution and the fungus was removed immediately and there is no damage or etching to the glass. I now have the front and back elements resting above bleach in a closed container so that should hopefully kill any remaining fungus. We finally have sun in Ottawa so I will leave it in sunlight tomorrow. Thanks for the help and advice!

[mdarnton]

I don't know that soaking a cemented element in anything is a good idea.

[Steven Tribe]

1. The fungus is likely dead. They soon run out of necesary "food" in a glass/brass/paint environment.

2. Fungus spores are everywhere in our living spaces. Obviously, it would be a good idea to clean away all obvious traces. Keeping the lens clean and in a dry atmosphere from now on is more important!

3. I don't understand the use of bleach. Ordinary cleaning will likely remove all traces of fungus growth (On a non-coated lens). Even if the fungus is active, there is no need to use "killer" chemicals. Remember that glass is classified a super-cooled liquid - not a solid, and strange things can happen with soaking for period. I have had two lenses that "devitrified" in quite dilute solutions.

4. The good thing is that I have never seen anything worse than some "blooming" patches on the lens surfaces - on non-coated glass.

Later.

Oh, you have already done a wipe on the lenses. Remember the inside of the barrel. Sun is quite unnecessary.

[Simon Benton]

I just had both elements in the open above a weak solution of bleach so the fumes could do the final job of killing any spores within the lens barrel. None of the elements were immersed in the bleach solution. I have now removed the elements from the fume area, wiped it again gently and put it back together.

Interestingly the front and back elements screw directly into an Alphax 3 shutter with the proper spacing. (I presume a Betax 3 would also work). Thanks for all the advice gentlemen.

[Mark Sawyer]

The fungus obviously found enough "necessary food" to grow a visible colony, and likely left behind spores to start a new colony. Best to eradicate it by fuming. Note that I only recommended soaking the single uncemented element. I very seriously doubt glass would devitrify in a household bleach solution. Until fairly recently, concentrated bleaches were sold and stored in glass bottles.

1. The fungus is likely dead. They soon run out of necesary "food" in a glass/brass/paint environment.

2. Fungus spores are everywhere in our living spaces. Obviously, it would be a good idea to clean away all obvious traces. Keeping the lens clean and in a dry atmosphere from now on is more important!

3. I don't understand the use of bleach. Ordinary cleaning will likely remove all traces of fungus growth (On a non-coated lens). Even if the fungus is active, there is no need to use "killer" chemicals. Remember that glass is classified a super-cooled liquid - not a solid, and strange things can happen with soaking for period. I have had two lenses that "devitrified" in quite dilute solutions.

4. The good thing is that I have never seen anything worse than some "blooming" patches on the lens surfaces - on non-coated glass.

Later.

Oh, you have already done a wipe on the lenses. Remember the inside of the barrel. Sun is quite unnecessary.

[Steven Tribe]

I wouldn't compare the characteristics of very diferent types of optical glass - some very close to alchemy -with the more domestic-use varieties!

I think initial growth is mostly dependent on a period of high humidty/Condensation. It is most common on the inside surfaces of lenses - away from circulating air - whilst there is most "food" (dust) and spores on exterior lens surfaces. The fungus growth I have seen on lenses (19th century) has been very sparce - very thin web type - with no real attachment to the glass surface. Now coated lenses which are attacked, are a very different story! They look like a skin complaint.