Using UV rays to kill lens fungus

[jason_galloway]

Hello,

I have a lens that has the very beginnings of fungus at the edge. I've Googled

it, and seen several mentions of using UV light to kill and stop the spread of

the fungus, typically by leaving the lens in the sun for a while. I was

wondering about this method, but using a different approach; I have a tanning

bed in my basement of my house and was considering placing the lens in it for a

bit to accomplish the same thing. I don't see any reason that this wouldn't

accomplish the same goal plus having the additional benefit of not getting the

lens really really hot and drying out rubber and plastic, but god knows there's

enough UV, those things will give you a sunburn in just a few minutes (I don't

ever use it, just get to pay the electric bill on it). Is anyone aware of any

problems with doing this that would cause harm to the lens? Will the UV method

even work on the Canon EF lenses (its not an L, just a standard 70-210mm f/3.5-

4.5) or are they coated in such a way that would prevent this (I don't figure

there is, if they blocked all UV light already there wouldn't be much a market

for UV filters)? Thanks!

[bob_sunley]

It will kill the fungus, no problem there.

Just make sure you take the lens caps off. :)

 

The coatings don't block the uv at all, the glass in the lens absorbs some, all depends on the glass chemistry and the wavelength of the UV.

 

Bob

[Hector Javkin]

<i>I don't see any reason that this wouldn't accomplish the same goal ...</i><p>One reason is that sunlight contains a mix of UV frequencies, while the frequencies of the safer tanning beds will provide UVA almost exclusively. The UVB range is much more effective at killing mold and other organisms. Nevertheless, a sufficient sufficient exposure to UVA might work.

[bobatkins]

Glass is pretty much opaque to UVB, so even if it's there in the light, it probably won't even get through the first element. Glass does transmit the longer wavelengths in the UVA range, but they aren't as effective at killing microorganisms.

 

While UV light might kill fungus with enough exposure, it won't remove it and it won't undue any damage to the coatings or the glass itself.

 

If the lens was expensive, I'd recommend having it opened up and the fungus cleaned out properly. Since it's probably not worth doing that on your lens, I'd try both the sunlight and tanning bed to see if you can halt its growth.

[beauh44]

Bob's right. I sure can't recommend "tough actin' Tinactin".

[jason_galloway]

I'll give it a shot, I only paid $150 for this second-hand so it certainly isn't worth having it repaired. The fungus is only very minor on the edge, it doesn't effect the exposure and hasn't caused any damage to the lens, I'm just trying to stop it from getting worse. I keep my gear in a dehumidifed room, this is my only lens that I have this problem with (it was there when I bought it), so if I can get it stopped I'm hoping I won't have many, if any, further issues with it. Thanks everyone!

[ken munn]

It might turn a rather fetching shade of brown!

[ed_hurst]

Keep it away from all your other equipment and bags as well - that stuff can spread very easily!

[kelly_flanigan1]

In survey equipment such as an old theodolite; WILD Heerbrugg had one NOT placing a damp instrument back into its case; it was placed in a cabinet with a light on; with air moving by. A case with a damp optical item has many faults; still air; no light; an moisture is trapped. One may wonder why more folks get athletes foot that fungus on ones hands. An old dresser drawer, a camera bag, a lens bag is often the perfect breading ground for fungus; still air; no light; trapped moisture, spores from other buddies.

[kelly_flanigan1]

maybe bread has fungus and mold too; the word should be breeding.:)

[rcsenn]

Will another type of radiation kill the fungus too, or maybe more efficeintly? Like X-ray or gamma?

[arie_vandervelden1]

Here's an idea: halogen lamps can be a good source of UV rays.<P>

From Wikipedia:<BR>

http://en.wikipedia.org/wiki/Halogen_lamp<P>

 

<I>some applications require ultraviolet radiation, and in such cases, the lamp envelope is made out of undoped quartz. Thus, the lamp becomes a source of UV-B radiation. Undoped quartz halogen lamps are used in some scientific, medical and dental instruments as a UV-B source</I><P>

 

I've got a little IKEA desk lamp that has a UV filter bolted in front of it... One could remove that filter and shine the bare light down the lens... might be more wieldy than a modifying a tanning booth.<P>f course, if the lens has a UV filter on it you'd wanna remove that too.

[wooi_loon]

As a microbiologist, UVA and UVB are not sufficient to kill fungus, they are quite resistant to UV, unless UVC (shortwave UV). You need at least above 100J/m2 UVC to kill 50% of the fungus. Tanning bed only supplied with UVA, so it wont works to stop the growth. Furthermore, as mentioned, glass will absorb most of the UV, even UVC. The only bet is send to repair centre.

[kelly_flanigan1]

Fungus rarely gets on lenses that are used on a regular basis; its more of a collector, worry wart; ebay/used camera stored in an old dresser drawer thing.:)

[jason_galloway]

<i>Fungus rarely gets on lenses that are used on a regular basis; its more of a collector, worry wart; ebay/used camera stored in an old dresser drawer thing.:)</i><BR><BR>

 

This particular lens was an EBay thing... OOPS! I've decided to go ahead and make it an EBay thing again, I'm sure there is someone out there that will overpay for a lens with fungus so I hope to get fairly close to what I paid for it out and chalk the rest up as a learning experience. A Photo.net member emailed me with one for sale at a very reasonable price in nice condition so I've decided to go ahead and buy a better quality version of the same lens (I'm no pro, as much as I want a 70-200L I just can't justify it, the little 70-210 will suit my needs just fine).