[Boris_Akunin]

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Hi,

I found some fungus it my recently acquired Canon FDn 85/1.8, it's located somewhere in/on the inside of the front lens group and it's limited to the edge. I doubt that it will have much if any impact on the image but I hesitate to use the lens.
(I know the Sub-Forum title is "Pentax SLR Lens Discussion" but this is about the fungus, not the specific lens)



I'm going to have to find the time to remove the front group and clean it but for now I lack the time and the tools.
I'm looking for a way to make the lens safe for use (without risking the fungus' spread to other gear) without taking it apart.
I've kept the lens under a 25W UV-lamp (CCFL) for the last week and the fungus appears to have become somewhat less dense.



Now I'm wondering whether the UV light (it's a cheap lamp without documentation so I don't know it's emission spectrum) is killing the fungus and perhaps even eating away at it's remnants.

If it kills off the fungus colony, the lens would at least become safe for use, so that's the question:

CAN IT?


regards
Jan

[LensBeginner]

Hi,
I'm not an expert on the matter, so I will leave to others to be more precise, but I did a little bit of googling in order to find more on the topic.
General consensus seems to be that:
1. it is dangerous to use, so it should be used with rigorous safety measures in place.
2. UV light can actually kill fungus
3. Dead fungus will still be there, which means they will not spread, but they will still degrade the optical quality of your lens. Also, they can eat at the coatings and etch the glass, so even a thorough cleaning in some case isn't enough to restore IQ...
4. The coating (supposing it's still in place) will not absorb UV, the glass will absorb some, though.
5. Some recommend exposing the lenses to direct sunlight, which should be a whole lot safer than UV lamps.
All this info is to be verified, of course.

[Boris_Akunin]

Hi,
I'm not an expert on the matter, so I will leave to others to be more precise, but I did a little bit of googling in order to find more on the topic.
General consensus seems to be that:
1. it is dangerous to use, so it should be used with rigorous safety measures in place.
2. UV light can actually kill fungus
3. Dead fungus will still be there, which means they will not spread, but they will still degrade the optical quality of your lens. Also, they can eat at the coatings and etch the glass, so even a thorough cleaning in some case isn't enough to restore IQ...
4. The coating (supposing it's still in place) will not absorb UV, the glass will absorb some, though.
5. Some recommend exposing the lenses to direct sunlight, which should be a whole lot safer than UV lamps.
All this info is to be verified, of course.

1: Thusfar, I've had it on my Canon T90 (I bought them together) for a couple of minutes, it has otherwise been kept at a distance from the rest of my gear.

2 & 4: The question is what dose of which parts of the UV spectrum the lens needs to be exposed to, what's the >safe dose< (or rather the >lethal dose<)?

More concretely:
- Does my kind of UV lamp emit the right kind of UV?
- How long does the UV-treatment have to last?

5: Northern Germany doesn't exactly get loads of direct sunlight, especially this time of year...
If sunlight works, what UV-lamp-exposure is equivalent to the sufficient sunlight-exposure?

Also: What's unsafe about UV lamps???

3: In this case the impact on IQ will probably be minor, I know what fungus can do to a lens quite well:


(Yes, that's my lens. Yes, the fungus has etched the glass. Yes, it's a [EXPLETIVE DELETED] shame!)

[jatrax]

UV can kill fungus. However, how do you know it is still alive?

Fungus needs warmth, moisture and food to grow, when one of those things runs out it dies. However, there will be plenty of other spores available to start growing again if the growth factors again become favorable. The spores are in the air all the time, so all lenses have them inside after some time. All that is needed is the right conditions to start the growth.

Having fungus grow inside a lens has very little relationship to whether it will ever grow again. I have never personally seen a fruiting body on lens fungus. My guess is that it does not grow long enough to produce them. The spores, however, are already present so it makes no difference if the current infestation fruits or not. If the conditions again become favorable the spores will germinate and the fungus will grow again.

Best thing is to keep the lens dry. UV light can kill it if it is alive but I think a lot of the success stories from using UV light actually are successful because the light warms up and dries out the lens. Sure, it kills the fungus that is currently growing but it does nothing about the spores still present.

[LensBeginner]

1: Thusfar, I've had it on my Canon T90 (I bought them together) for a couple of minutes, it has otherwise been kept at a distance from the rest of my gear.

2 & 4: The question is what dose of which parts of the UV spectrum the lens needs to be exposed to, what's the >safe dose< (or rather the >lethal dose<)?

More concretely:
- Does my kind of UV lamp emit the right kind of UV?
- How long does the UV-treatment have to last?

5: Northern Germany doesn't exactly get loads of direct sunlight, especially this time of year...
If sunlight works, what UV-lamp-exposure is equivalent to the sufficient sunlight-exposure?

Also: What's unsafe about UV lamps???

3: In this case the impact on IQ will probably be minor, I know what fungus can do to a lens quite well:


(Yes, that's my lens. Yes, the fungus has etched the glass. Yes, it's a [EXPLETIVE DELETED] shame!)

Ultraviolet - Wikipedia, the free encyclopedia
This is a good start...
Re. item No. 1 I meant dangerous to you, not the lenses...

[psoo]

UV can kill fungus. However, how do you know it is still alive?

Fungus needs warmth, moisture and food to grow, when one of those things runs out it dies. However, there will be plenty of other spores available to start growing again if the growth factors again become favorable. The spores are in the air all the time, so all lenses have them inside after some time. All that is needed is the right conditions to start the growth.

Having fungus grow inside a lens has very little relationship to whether it will ever grow again. I have never personally seen a fruiting body on lens fungus. My guess is that it does not grow long enough to produce them. The spores, however, are already present so it makes no difference if the current infestation fruits or not. If the conditions again become favorable the spores will germinate and the fungus will grow again.

Best thing is to keep the lens dry. UV light can kill it if it is alive but I think a lot of the success stories from using UV light actually are successful because the light warms up and dries out the lens. Sure, it kills the fungus that is currently growing but it does nothing about the spores still present.

I know that many people are very careful to keep lenses infected with fungus away from other lenses to avoid contamination. However, isn't fungus more likely to be present on the camera body, camera cases and bags, and other equipment, where it may not as easily be seen and detected? I would expect that lenses would be much more likely to be infected by fungus from these sources that from a source within a lens.

[waterfall]

Fungus can be killed but any spores released during reproductive stage will survive. Spores need relative humidity > 40 percent to start growing. At least the fungal spores from garden variety 45 degrees north latitude environment. Tropical spores fungi are complete unknowns to me.

Seems to me if the fungal hyphae are on the interior side of the outer element, there should be no risk of contaminating the camera body. But I would isolate the lens in storage, away from all other lenses and camera bodies.

[jatrax]

I know that many people are very careful to keep lenses infected with fungus away from other lenses to avoid contamination. However, isn't fungus more likely to be present on the camera body, camera cases and bags, and other equipment, where it may not as easily be seen and detected? I would expect that lenses would be much more likely to be infected by fungus from these sources that from a source within a lens.

Fungal spores are present in the air at all times. So yes they will be on your camera body, your gear bag and on your lenses. Zooms especially will suck them in as you zoom in and out. So there is no way to really 'clean' your gear from fungus. Unless you keep it in a sterile, filtered environment and never go outside.

The only practical way to prevent fungus is to make sure the environment never becomes conducive to it's growth. If you get your gear wet, make sure you dry it properly as soon as you can, use a dry box if you live in a high humidity location, be very careful with temperature changes such as leaving air conditioning, or going into a warm house from the cold outside.

I've never understood the logic in keeping an 'infected' lens away from other gear. Makes no difference. ALL of your gear is ALREADY infected. Just waiting for the right conditions to grow. And I have never seen a fruiting body on lens fungus. Not to say that it would be impossible but I doubt that fungus in a lens lives long enough to produce spores.

[Boris_Akunin]

Ultraviolet - Wikipedia, the free encyclopedia
This is a good start...
Re. item No. 1 I meant dangerous to you, not the lenses...

Right, Wikipedia says this:

240–280 nm: Disinfection, decontamination of surfaces and water (DNA absorption has a peak at 260 nm)

so I probably need a UV source with some emissions at 260nm.

The common fluorescent lamp relies on fluorescence. Inside the glass tube is a partial vacuum and a small amount of mercury. An electric discharge in the tube causes the mercury atoms to emit ultraviolet light. The tube is lined with a coating of a fluorescent material, called the phosphor, which absorbs the ultraviolet and re-emits visible light. Fluorescent lighting is more energy-efficient than incandescent lighting elements. However, the uneven spectrum of traditional fluorescent lamps may cause certain colors to appear different than when illuminated by incandescent light or daylight. The mercury vapor emission spectrum is dominated by a short-wave UV line at 254 nm (which provides most of the energy to the phosphors)

So a CCFL starts out with the rigth wave length (~254nm) but it mostly converted to the wrong wavelength

Blacklights are a subset of fluorescent lamps that are used to provide near ultraviolet light (at about 360 nm wavelength). They are built in the same fashion as conventional fluorescent lamps but the glass tube is coated with a phosphor that converts the short-wave UV within the tube to long-wave UV rather than to visible light. They are used to provoke fluorescence (to provide dramatic effects using blacklight paint and to detect materials such as urine and certain dyes that would be invisible in visible light) as well as to attract insects to bug zappers.

The usual cheap UV-bulbs appear to be blacklights (sold as party supplies), so those emit the wrong kind of UV.

350–370 nm: Bug zappers (flies are most attracted to light at 365 nm)

UV-lamps meant for bug zappers are out too...

Germicidal UV is delivered by a mercury-vapor lamp that emits UV at the germicidal wavelength. Mercury vapour emits at 254 nm.

These low-pressure lamps have a typical efficiency of approximately thirty to forty percent, meaning that for every 100 watts of electricity consumed by the lamp, they will produce approximately 30–40 watts of total UV output.

THERE WE GO!

So our best chance to kill fungus - if UV can kill fungus through the lens glass at all - is a lamp like this one (or a stronger version. Since CCFLs only get longer, high-pressure mercury-vapor lamps would be the best option but those are rather expensive...)

Characteristics
• Issued short-wave UV radiation with a peak of 253.7 nm (UV-C) for sterilization
• glass bulb of the lamp filters out the 185 nm ozone-forming region
• Internal protective coating reduces the deterioration of the UVC-yield
• lamp is provided with warning UV-C radiation

Application
• destruction or deactivation of bacteria, viruses and other micro-organisms
• Air and surface disinfection in hospitals, bacteriological research and in the pharmaceutical and food-processing industries such as dairies, breweries and bakeries
• disinfection of drinking water, wastewater, swimming pools, air conditioners, refrigerators, packaging materials etc.
• For use in many photochemical processes

I think, I'll get these two and try it:
http://www.amazon.de/gp/product/B001VTPDX8/ref=ox_sc_act_title_3?ie=UTF8&psc...A3JV61L0NEVASN
http://www.eoffice24.com/tischleuchte-brilliant-job-klemme-titan.html

[promacjoe]

This is one of the reasons why I always follow a few simple rules for handling my equipment.

1: wash your hands. Simply washing your hands can help prevent bacteria from getting on your equipment. Hand sanitizers when you're out and about also help. Also avoid handling your equipment after eating greasy or salty foods such as fried chicken or french fries. These substances can damage the electronics encodings on your camera.

2: never blow on your lens with your mouth. Your mouth has two elements that are not desirable on your lens. One is a mild acid, The other is bacteria that can etch the coding on your lens.

3: keep your lenses dry. Even though some lenses or water resistant, I still don't believe that it is a good idea to use them out in the rain for any extended period of time. If you use your equipment in the rain, Bring it in and dry it off quickly. Wrap the lens with a protective cloth and placed it in a bag of uncooked rice to help dry it thoroughly.

Using these rules has helped me to avoid any noticeable fungus or bacteria in my equipment. I have lenses that were made back in the 60s and early 70s that have no noticeable fungus in them.

Note: certain types of UV light can be damaging to your eyes. For instance a blacklight is not damaging to your eyes however UV A and UV B can be damaging to your eyes. A UV lamp that is unknown, should be treated as one that can damage your eyes. Never look at a UV lamp of unknown type directly or indirectly for that matter. Only used them in a sealed light safe cabinet or container.

Protect your eyes, they're worth more than any Lens on the market.

[Boris_Akunin]

Seems to me if the fungal hyphae are on the interior side of the outer element, there should be no risk of contaminating the camera body. But I would isolate the lens in storage, away from all other lenses and camera bodies.

The fungus is definitely further in than the front element, my best guess is that it's on the rear surface of the third element, here's the lens diagram of the FD version (the FDn has the same formula afaik):



---------- Post added 11-14-14 at 12:06 AM ----------

Note: certain types of UV light can be damaging to your eyes. For instance a blacklight is not damaging to your eyes however UV A and UV B can be damaging to your eyes. A UV lamp that is unknown, should be treated as one that can damage your eyes. Never look at a UV lamp of unknown type directly or indirectly for that matter. Only used them in a sealed light safe cabinet or container.

Protect your eyes, they're worth more than any Lens on the market.

You're right, blacklight (near-visible UV-A, the lamps have their peak at ~365nm) is relatively harmless, UV appears to be most eye-damaging around the border between UV-B and UV-C:

The eye is most sensitive to damage by UV in the lower UVC band at 265-275 nm. Light of this wavelength is almost absent from sunlight, but is found in welder's arc lights and other artificial sources. Exposure to these causes welder's flash or arc eye (photokeratitis), and can lead to cataracts, pterygium,[37][38] and pinguecula formation. To a lesser extent, UVB in sunlight from 310-280 nm also causes photokeratitis ("snow blindness"), and the cornea, the lens, and the retina can be damaged.

• Ultraviolet A (UVA) | 400 – 315 nm | long wave, black light, not absorbed by the ozone layer
• Ultraviolet B (UVB) | 315 – 280 nm | medium wave, mostly absorbed by the ozone layer
• Ultraviolet C (UVC) | 280 – 100 nm | short wave, germicidal, completely absorbed by the ozone layer and atmosphere

So the lamp that I'm using now is fairly safe (I don't exactly stare at it...) but the more useful lamps (germicidal ~254nm lamps) are also the most dangerous.
I'll set up the >treatment space< in a closed cupboard and set up the lamp so that I can switch it on and off before I open the cupboard. That should keep my eyes protected.


Right know, my lenses are "stored" on an open shelf with the caps on. It's a dry sunlit room but there's room for improvement.
I'm thinking of repurposing this thing:



I'll throw in a heap of silica gel packs and keep the caps off, that should do it.

What do you think?

[psoo]

Fungal spores are present in the air at all times. So yes they will be on your camera body, your gear bag and on your lenses. Zooms especially will suck them in as you zoom in and out. So there is no way to really 'clean' your gear from fungus. Unless you keep it in a sterile, filtered environment and never go outside.

The only practical way to prevent fungus is to make sure the environment never becomes conducive to it's growth. If you get your gear wet, make sure you dry it properly as soon as you can, use a dry box if you live in a high humidity location, be very careful with temperature changes such as leaving air conditioning, or going into a warm house from the cold outside.

I've never understood the logic in keeping an 'infected' lens away from other gear. Makes no difference. ALL of your gear is ALREADY infected. Just waiting for the right conditions to grow. And I have never seen a fruiting body on lens fungus. Not to say that it would be impossible but I doubt that fungus in a lens lives long enough to produce spores.

Hi Jatrax, I agree with you that keeping an internally affected lens away from all other equipment does no good. However, I would like to ask if anybody has concrete evidence that fungal contamination can spread this way. If not, lets discard this old wive's tale.

[kh1234567890]

In my experience fungus usually starts from some organic matter inside the lens - a dead insect, breadcrumb etc. It then spreads as it goes looking for more food. UV might kill it - if you can get enough UV at a short enough wavelength through the glass - but it will not remove it. The only cure is to disassemble and clean.

As for keeping the RH low and keeping dust out - I've got one of these. List price $1,000+. eBay price £50

Works a treat.

[Boris_Akunin]

UV might kill it - if you can get enough UV at a short enough wavelength through the glass - but it will not remove it. The only cure is to disassemble and clean.

I've got a 11w UV-C (germicidal, peak at 254nm) lamp on the way, I don't know if ~3-4.5W output in the right range:

At certain wavelengths UV is mutagenic to bacteria, viruses and other micro-organisms. At a wavelength of 2,537 Angstroms (254 nm)[6] UV will break the molecular bonds within micro-organismal DNA, producing thymine dimers in their DNA thereby destroying them, rendering them harmless or prohibiting growth and reproduction. It is a process similar to the UV effect of longer wavelengths (UVB) on humans, such as sunburn or sun glare. Micro-organisms have less protection from UV and cannot survive prolonged exposure to it.

The lens glass will absorb most of the UV but not all, so it's just a matter of time...

As for keeping the RH low and keeping dust out - I've got one of these. List price $1,000+. eBay price £50

Works a treat.

Thanks! Now I have another thing to hunt for on ebay...

[Boris_Akunin]

Right, my UV treatment space is set up, I think this should be safe enough for my eyes (for obvious reasons, the pictures show a normal lamp instead of the UV-C lamp):









I'll put some aluminium foil under the lenses to reflect some UV back up the lens, all other surfaces are either wood or cardboard.
AFAIK, wood and paper/cardboard should mostly absorb UV rather then reflect it.

The lens next to the 85/1.8 is a Minolta MC 28mm f/2.5 with a slight yellow tint (due to radioactive glas elements), UV-treatment is supposed to help with that...

EDIT:
Here's the setup in action:



Obviously, I took the photo without looking.

Note:
My setup should deliver at least 130W/m² of UV-C to the lenses' front elements.
At sea level, daylight (at the equator, around noon) contains ~80W/m² of UV-A, ~4W/m² and <1W/m² of UV-C.