[radman]

Hi

Please tell me about lenses with fungus.

I a no expert but the lens I found at the thrift shop looks to have fungus on the rear element. I could not wipe it off, it looks like a branching pattern and almost like a cobweb.
It covers most of the rear element but I can certainly still see through the lens from front to back.

It is a screw mount super tak 135/3.5. That otherwise looks OK. I don't have an adapter
But if I get this lens and the Honeywell that it is attached to for $10 then I would use this lens on my k3 with an adapter.

Can fungus move from the lens to my k3 ?

Thank you

[jatrax]

Can fungus move from the lens to my k3 ?

No. Well yes it could if it was alive, but since it's dead, no. Understand that fungus (like any living thing) grows or dies. So if it is alive it keeps growing, and if it was still growing it would cover the entire lens as well as the display case. Fungal spores on the other hand can survive almost anything and are present in the air and most surfaces including your camera and this lens. If the environmental conditions are correct the spores will grow and you have fungus.

So to answer your question would I buy a lens with fungus? Yes, and I've done so a number of times. But only if there is a good reason. For example a rare lens that does not come up for sale often or a good lens at a really bargain price. Would I buy a super tak 135 f/3.5 with fungus? No. They are common and pristine ones go for less than $40. Saving that amount of money is not worth the time and trouble to clean it, FOR ME. YMMV.

Remember you will need to clean this lens, unless the fungus is very slight and off to the side it will have some impact on the lens, usually more glare or lower contrast. Cleaning it yourself is possible but I usually factor in the cost of professional repair (even if I do it myself) to the cost. In this case, maybe $50 for a good cleaning. Which makes the lens cost about $60, and you can get a nice one for less.

I've no particular aversion to fungus, but it always comes down to money. Do the math before you buy.

[bakerking31]

I see those on craigslist regularly for $20 I wouldn't pay $10 less for one with fungus

[mikeSF]

no way. keep shopping for a clean copy.

[stevebrot]

The short answer is that I treat fungus as an infection. Yes, there are fungal spore in the air, but visible fungus on a lens is proof positive of a pathogen...a mold that is capable of colonizing the surface of optical glass and likely also very slow growing and also quite possibly still alive. Are infectious spore present? Good question. If your brother has athlete's foot, do you borrow his shoes?

My practice?

• If fungus is discovered, the lens is immediately placed in isolation in a zip-lock bag and I wash my hands well. In the case of a newly unboxed lens, I also clean the surrounding area with 10% bleach water.
• On a new purchase, I return the lens
• If the lens remains in the house, I may disassemble using clean technique and attempt remediation and disinfection. If obviously beyond redemption, into the trash it goes.

Fungus is a huge problem with microscopes and other optical instruments. Since many who use microscopes in their work also have training in microbiology, there is a fair amount of information out there regarding risk factors, routes of infection, responsible species (i.d.'ed by culture from the lens...so much for dead fungus, eh?), pathogenesis (how the damage is done),* prevention, and remediation. Interestingly, routine use of fungicides in the storage cabinet is recommended by some sources.

Do a Goggle search for "fungus microscope lens" and be prepared to be horrified, amazed, and enlightened.

https://micro.magnet.fsu.edu/primer/anatomy/cleaning.html (towards bottom)

Fungus: how to prevent growth and remove it from optical components

Know Your Lens Fungus



Steve

* One source stated that fluorine compounds in the glass and/or coatings are metabolized by some fungi to hydrofluoric acid (HF) which is highly effective in etching glass, but apparently does not bother the fungus.

(...feels fortunate to live in a part of the world where lens fungus risk is fairly low...)