Ultraviolet light for lens maintenance?

Digger Odell · Jan 18, 2021

Hello Folks,

So my question as a owner of several cameras/lenses. These lenses don't get used on a monthly basis, and could remain with me for 20 years or more, and having seen fungus damage on several purchased lenses recently. Would it be beneficial to expose the lenses to UV light once in a while. I'm thinking to reduce/eliminate fungus. What type of light would you recommend? Living where I do, this time of year, sunlight is not very practical, I don't think we have had a sunny day for a month or more. I see some UV black-light bulbs for sale, what do you all think?

Sirius Glass · Jan 18, 2021

Just put the lenses out where they will get sun for several days or a week with the irises open. Then turn them around and repeat. That will work much better if the lens caps are removed first.

Ariston · Jan 18, 2021

Don't leave them in the sun mounted to a camera with a cloth shutter.

Fungus needs moisture, so keep them in a dry place. Desiccants are cheap.

Scott Micciche · Jan 18, 2021

You can use a reptile LED (non-heating) UV-C for that purpose. I used one to de-yellow my 105mm Super Tak and it worked quite well. Avoid heading the elements.

Jojje · Jan 18, 2021

UV light tube of our pet tortoise's terrarium did indeed kill the fungus in a Color-Skopar. Explore a pet shop, not cheap, though.

AgX · Jan 18, 2021

Is there any proof that lens fungus would be affected by UV light at all?

mshchem · Jan 18, 2021

Ariston said:
Don't leave them in the sun mounted to a camera with a cloth shutter.

Fungus needs moisture, so keep them in a dry place. Desiccants are cheap.

+1 Perfect

Huss · Jan 18, 2021

I bought a UV-C lamp. Then found out that UV-C does NOT penetrate glass.

https://hps.org/publicinformation/ate/q12082.html

What I bought:

https://uvcleanhouse.com/collections/customer-favorites/products/uv-sanitizing-portable-desk-lamp

Sirius Glass · Jan 18, 2021

Sirius Glass said:
Just put the lenses out where they will get sun for several days or a week with the irises open. Then turn them around and repeat. That will work much better if the lens caps are removed first.

Take the lenses off the cameras. Otherwise how are you going to get light going into the rear elements?

Scott Micciche · Jan 18, 2021

Huss said:
I bought a UV-C lamp. Then found out that UV-C does NOT penetrate glass.

https://hps.org/publicinformation/ate/q12082.html

What I bought:

https://uvcleanhouse.com/collections/customer-favorites/products/uv-sanitizing-portable-desk-lamp

Lens glass is not standard window glass designed for homes. UV-C penetrates camera lenses just fine. Many thorium lenses have been de-yellowed using UV-C, some with UV-A/B.

Auer · Jan 18, 2021

I just left my Canon 1.2 58mm on the windowsill to de-yellow for a few days, worked well in the sunlight.

itsdoable · Jan 18, 2021

Like Sirius & Auer, I use the Sun. You just have to be patient, especially if your area does not get a lot of sun.

I use the sun for UV set optical epoxy too.

Sirius Glass · Jan 18, 2021

itsdoable said:
Like Sirius & Auer, I use the Sun. You just have to be patient, especially if your area does not get a lot of sun.

I use the sun for UV set optical epoxy too.

If you are in the Northern Hemisphere, do not use a north facing window. If you are in the Southern Hemisphere, do not use a south facing window.

Huss · Jan 19, 2021

Scott Micciche said:
Lens glass is not standard window glass designed for homes. UV-C penetrates camera lenses just fine. Many thorium lenses have been de-yellowed using UV-C, some with UV-A/B.

Do you have a link to that information? Some kind of technical reference?

Sirius Glass · Jan 19, 2021

Huss said:
Do you have a link to that information? Some kind of technical reference?

Search the threads on this website. There is a lot of documentation already there.

AgX · Jan 19, 2021

Maybe from de-yellowing and cement curing we could get back to fungus.

xya · Jan 19, 2021

AgX said:
Maybe from de-yellowing and cement curing we could get back to fungus.

good idea. I tried sunlight and uv-light from bulbs for plants and animals, it never worked to get rid of the slightest existing fungus. but it seems to me that exposing lenses and cameras to sunlight, even behind a window pane, prevents fungus, be it on the glass or be it on the leather bellows. since I do so (only for expensive cameras and lenses), I haven't had problems any more. I let them rest on a table in plain sunlight twice a year for 3 days on either side, shutter and aperture open if possible. and please check that the focussed light can't burn holes into your table, happened once to me.

a greater part of the fungus was on the outside of the elements, so my repair man could get rid of it by taking the lens apart. and one last thought: most fungus was on lenses from japan and russia. maybe a climate question.

Huss · Jan 19, 2021

xya said:
... and one last thought: most fungus was on lenses from japan and russia. maybe a climate question.

I see it from Japanese sellers all the time. Anything I search for on ebay, description will be excellent ++++ or mint and then a mention of slight fungus..

eli griggs · Jan 19, 2021

If you have a car that has windows that will allow you to be sunburned, place the lens focus on infinity and stick in on a aluminum pan, with a thick cardboard panel(s) to isolate between the pan bottom and upholstery.

Put the aperture wide open and allow the sun to stay on them for a day or so, flipping it once.

Remember that if you have a bright, white paper or aluminum foil, you can cut a circle that will fit inside the lens cap (a slightly large cut might give you a concave effect) and allow that to bounce even more light around the lens.

Also, aperture down to the smallest F stop Iris, to ensure any spores on the blades, front and back receive the same treatment.

A plain glass house window, usually older manufacture, can do the same, if you can sunburn/tan through it, and the nice Pentax 135 2.5 lens I had, came with fungus inside it, so I placed it in that window for some number of days, and it stopped the fungus dead.

I was lucky, as the fungus had no etched the glass, and when I cleaned it while apart, Hydrogen Peroxide removed the dead 'tissue' and Eclipse Lens Cleaner gave me beautiful glass to reassemble.

Cloudy days with high UV are also very good too, so just because you can no see direct visable light, does no mean you can no try to kill your lens fungus.

IMO.

Sirius Glass · Jan 19, 2021

eli griggs said:
If you have a car that has windows that will allow you to be sunburned, place the lens focus on infinity and stick in on a aluminum pan, with a thick cardboard panel(s) to isolate between the pan bottom and upholstery.

Put the aperture wide open and allow the sun to stay on them for a day or so, flipping it once.

Also, aperture down to the smallest F stop Iris, to ensure any spores on the blades, front and back receive the same treatment.

A plain glass house window, usually older manufacture, can do the same, if you can sunburn/tan through it, and the nice Pentax 135 2.5 lens I had, came with fungus inside it, so I placed it in that window for some number of days, and it stopped the fungus dead.

I was lucky, as the fungus had no etched the glass, and when I cleaned it while apart, Hydrogen Peroxide removed the dead 'tissue' and Eclipse Lens Cleaner gave me beautiful glass to reassemble.

Cloudy days with high UV are also very good too, so just because you can no see direct visable light, does no mean you can no try to kill your lens fungus.

IMO.

I had not thought about doing it in a car. But I would opt for outside on a balcony, patio or porch.

itsdoable · Jan 19, 2021

xya said:
AgX said:

Maybe from de-yellowing and cement curing we could get back to fungus.

Click to expand...

good idea. I tried sunlight and uv-light from bulbs for plants and animals, it never worked to get rid of the slightest existing fungus....

UV does not get rid of fungus, it just kills and sterilized the lens. You still have to go in and clean out the dead fungus...

Huss · Jan 19, 2021

Sirius Glass said:
I had not thought about doing it in a car. But I would opt for outside on a balcony, patio or porch.

It's a bad idea doing it in your car unless you don't mind the potential of a car fire. As well as the suggestion of setting the lens to infinity. You want to do the opposite. Setting it to infinity focuses the light resulting in fire potential.

eli griggs · Jan 19, 2021

Huss said:
It's a bad idea doing it in your car unless you don't mind the potential of a car fire. As well as the suggestion of setting the lens to infinity. You want to do the opposite. Setting it to infinity focuses the light resulting in fire potential.

That point about fire is the reason for the aluminum pans with cardboard keeping the pan off the car's furniture.

Unless enameled in a light colour, I think iron pans are a bad idea too.

Even placing the lens on infinity helps keep the lens from starting fires, as a short focal length will be focused within the car, where it can more easily catch fire.

If you are that worried, you can use my suggestion to take a bright white paper (or thin card stock) or aluminium foil to line the lens cap so more light is scattered within the lens itself.

IMO.

AgX · Jan 19, 2021

My point is that there are countless, most diverse fungi. And not all live in the dark. A lot of them are exposed to light in nature.

In storing lenses storing is often connectected to both, darkness and humidity. In bringing lenses to light we often bring them into a less humid atmosphere too.

Scott Micciche · Jan 20, 2021

One also has to be careful with heat. Heat and lenses don't mix, balsam separation and migration of grease can be the result of placing the lens in heated environments.

Ultraviolet light for lens maintenance?

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