[psoo]

I recently purchased a Tel-Takumar 200 mm, f/5.6 lens from an antique store, but on careful examination found that an internal lens surface had traces of fungus. Apart from the fungus it is in mint condition. I read somewhere in these forums that somebody had greatly reduced a fungus problem by exposing the lens to natural sunlight for several months from a window in his home. I know that UV bulbs can be bought from stores that are used for potted plant growth, and wonder if anybody had used this method. I believe that the UV light that kills fungi needs to have an optimum wavelength and want to know if such light bulbs will work.

[MJSfoto1956]

plain old sunlight (however, not behind a UV-coated window) works well -- but you must take care that the focus point is not aimed at anything flammable. .

M

[jatrax]

It is already dead. If it was not it would be growing and i'll bet it is not. No need to irradiate, or anything else.

If you want the filaments removed that is different but the fungus itself is already dead.

[robthebloke]

Semi-Disagree with jatrax. The fungus may be dead, but there may be spores. A blast of uv isn't going to do the lens any harm, so why not? Better than finding a fungal infection post slightly misty shooting session

[Tonytee]

I recently purchased a Tel-Takumar 200 mm, f/5.6 lens from an antique store, but on careful examination found that an internal lens surface had traces of fungus. Apart from the fungus it is in mint condition. I read somewhere in these forums that somebody had greatly reduced a fungus problem by exposing the lens to natural sunlight for several months from a window in his home. I know that UV bulbs can be bought from stores that are used for potted plant growth, and wonder if anybody had used this method. I believe that the UV light that kills fungi needs to have an optimum wavelength and want to know if such light bulbs will work.

Here in your opening statement you stated that the surface of a lens had traces of fungus. My question to you is, Have you verified that what you are looking at is in fact fungus? There are many times when upon close examination a person could easily mistake a small accumulation of dust particles for fungus. If there is fungus on the optics, it is my advice that by now it has etched itself into the glass. Also, if the fungus does not appear to be migrating across the surface of the lens, there is a real possibility that it is digging deeper into the optics. Speaking for myself I had this same situation, brought to my favorite service center. They had it for two days and told me that all it needed was a good cleaning and some minor adjustments. I believe it would behoove you to have it checked out. I hope this helps.

Rgds,

Tonytee

[jatrax]

UV will not kill the spores without extensive treatment. But it doesn't matter because the spores are present in the air. Kill all of them, sterilize the lens and they will be back as soon as the lens takes in air.

Fungus grows until it uses up available moisture or food then dies leaving the dead filaments.

Keep the lens dry = no fungus.

[MJSfoto1956]

I would still recommend the "extensive treatment" approach -- it can only help.

Michael

[jatrax]

Sigh........ .........

[MJSfoto1956]

Sigh........ .........

Oh please! There is plenty of anecdotal evidence of the benefits of UV irradiation: Treating fungus with UV stunning finding

As I said, it can't hurt -- it can only help.

YMMV

Michael

[pentaxus]

I'm OCD. I would be compelled to take the lens apart.

[WPRESTO]

ISFA UV light will not penetrate some types of glass, is it reasonably certain it would get to fungus on an interior lens surface?

[jatrax]

Michael yes technically uv will kill fungus if applied in sufficient doses at the correct wavelength. But the uv argument misses the point that the fungus is already dead. And those internet posts proving it works miss the fact that uv lamps generate heat which dries out the lens thus killing the fungus. The same as using any heat source such as a warm windowsill or a hairdryer. Or miss the fact it is easy to prove you killed something that was already dead

But you are correct it will not hurt so believe what you wish.

And sorry for the possibly snarky post above this issue is just very frustrating because it is an area in which I worked professionally for over 30 years.

[psoo]

Here in your opening statement you stated that the surface of a lens had traces of fungus. My question to you is, Have you verified that what you are looking at is in fact fungus? There are many times when upon close examination a person could easily mistake a small accumulation of dust particles for fungus. If there is fungus on the optics, it is my advice that by now it has etched itself into the glass. Also, if the fungus does not appear to be migrating across the surface of the lens, there is a real possibility that it is digging deeper into the optics. Speaking for myself I had this same situation, brought to my favorite service center. They had it for two days and told me that all it needed was a good cleaning and some minor adjustments. I believe it would behoove you to have it checked out. I hope this helps.

Rgds,

Tonytee

Hi Tonytee. I'm pretty sure it is fungus. I've seen photos in previous threads, and the filaments in the affected areas of my lens are very similar. It's not a big infection and It may not be a practical problem when I use the lens.

[psoo]

I'd like to thank everybody who made comments on this thread. I benefited greatly from the spirited discussions and I feel that the small areas of fungus on my lens are not serious, and are probably not actively growing. I may give the lens a shot of sunlight once in a while since it may do some good. I'll keep the lens isolated although It's hard for me to envision the fungus sneaking out of the lens and infecting other equipment. I feel that it must be safely encapsulated within the lens. Thanks again.

[osv]

Fungus on Lenses | ZEISS United States