Can a UV lamp kill fungus and make the lens safe for use?

LensBeginner · 11-17-2014, 11:24 AM

Originally posted by 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):
*snip*

You did your homework alright!

Can't wait to see if it works...

Boris_Akunin · 11-17-2014, 04:43 PM

One last change to the setup:

Boris_Akunin · 11-18-2014, 06:18 PM

It's been running for two days and there are no temperature problems, the thermometer that I've placed right next to the lenses hasn't moved beyond the 20°C mark (the room temp. is ~16-19°C) and the lenses still only barely feel warm to the touch (below 30°C, I think).

There is no smell of ozone, the lamp's 185nm filter seems to be working. So if this turns out to work, ozone procuction inside the lens is probably out as a cause. (And if it doesn't work at all, UV-C is out out too and high intensity UV-A remains as the only non-invasive option to try)

BTW, it's interesting to see the difference between the blueish light reflected off the aluminium foil (alu is highly reflective across the UV spectrum) and the greenish light reflected of the wood and cardboard (high absorption in the UV spectrum, apparently also at the visible edge).

**Spodeworld** · 11-19-2014, 07:32 AM

I've searched out the original question in the past. Yes, UV can kill the fungus BUT the glass in the lens attenuates the effect to the point where a UV light will not accomplish what you are looking for.

BTW, I remember Eric responding to a question I once had about fungus jumping lenses, and he said that that does not happen. That is, a lens with fungus in it does not pose a threat to the others that may be in the same drawer.

kh1234567890 · 11-19-2014, 09:28 AM

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/143593-how-...ml#post1500172

**Spodeworld** · 11-19-2014, 01:36 PM

That's pretty awesome. If you have a source of sufficient strength, then you can overcome the filtering effects of the glass. Wish I had access to it.

Boris_Akunin · 11-21-2014, 05:19 AM

First status update:
There's no visible change in the fungus, idk if it's dead or alive but it's definitely not disintegrating.

My two yellowed lenses (Minolta MC 28/3.5, Soligor 17/4) have improved a lot, the tint is almost gone in both.
I've had the Soligor under a UV-A lamp (25W, peak output around 365nm) before without any change. UV-C seems to work a lot better.

Boris_Akunin · 11-22-2014, 01:41 PM

I noticed that the UV was starting to bleach out the black finish on the Minolta... that shouldn't happen anymore:

LensBeginner · 11-22-2014, 04:58 PM

Originally posted by Boris_Akunin

I noticed that the UV was starting to bleach out the black finish on the Minolta... that shouldn't happen anymore:

An interesting side effect...
And then they said that tin foil hats are useless...

Boris_Akunin · 11-22-2014, 05:03 PM

Originally posted by LensBeginner

An interesting side effect...
And then they said that tin foil hats are useless...

The change was only visible at the front of the lens (directly exposed to the UV lamp), so UV-C exposure was way beyond normal sunlight-levels.

Boris_Akunin · 01-04-2015, 06:51 PM

Regarding the unwanted effects of UV-C, here's how much my Minolta MC 28/2.5 changed (left: MD 28/2 for comparison):

Before:

After 3 weeks of UV-C (>130w/m²):

11-18-2014, 06:18 PM	#18
Boris_Akunin Veteran Member Join Date: Aug 2012 Location: Bremen, Germany Photos: Gallery Posts: 674 Original Poster	It's been running for two days and there are no temperature problems, the thermometer that I've placed right next to the lenses hasn't moved beyond the 20°C mark (the room temp. is ~16-19°C) and the lenses still only barely feel warm to the touch (below 30°C, I think). There is no smell of ozone, the lamp's 185nm filter seems to be working. So if this turns out to work, ozone procuction inside the lens is probably out as a cause. (And if it doesn't work at all, UV-C is out out too and high intensity UV-A remains as the only non-invasive option to try) BTW, it's interesting to see the difference between the blueish light reflected off the aluminium foil (alu is highly reflective across the UV spectrum) and the greenish light reflected of the wood and cardboard (high absorption in the UV spectrum, apparently also at the visible edge). Last edited by Boris_Akunin; 11-18-2014 at 06:38 PM.

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11-17-2014, 11:24 AM	#16
LensBeginner Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 4,696	Originally posted by 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): snip You did your homework alright! Can't wait to see if it works...

11-17-2014, 04:43 PM	#17
Boris_Akunin Veteran Member Join Date: Aug 2012 Location: Bremen, Germany Photos: Gallery Posts: 674 Original Poster	One last change to the setup:

11-19-2014, 07:32 AM	#19
Spodeworld Site Supporter Join Date: Aug 2011 Location: New Joisey Photos: Gallery \| Albums Posts: 1,370	I've searched out the original question in the past. Yes, UV can kill the fungus BUT the glass in the lens attenuates the effect to the point where a UV light will not accomplish what you are looking for. BTW, I remember Eric responding to a question I once had about fungus jumping lenses, and he said that that does not happen. That is, a lens with fungus in it does not pose a threat to the others that may be in the same drawer.

11-19-2014, 09:28 AM	#20
kh1234567890 Veteran Member Join Date: Sep 2010 Location: Manchester, UK Photos: Gallery Posts: 2,653	https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/143593-how-...ml#post1500172

11-19-2014, 01:36 PM	#21
Spodeworld Site Supporter Join Date: Aug 2011 Location: New Joisey Photos: Gallery \| Albums Posts: 1,370	That's pretty awesome. If you have a source of sufficient strength, then you can overcome the filtering effects of the glass. Wish I had access to it.

11-21-2014, 05:19 AM	#22
Boris_Akunin Veteran Member Join Date: Aug 2012 Location: Bremen, Germany Photos: Gallery Posts: 674 Original Poster	First status update: There's no visible change in the fungus, idk if it's dead or alive but it's definitely not disintegrating. My two yellowed lenses (Minolta MC 28/3.5, Soligor 17/4) have improved a lot, the tint is almost gone in both. I've had the Soligor under a UV-A lamp (25W, peak output around 365nm) before without any change. UV-C seems to work a lot better.

11-22-2014, 01:41 PM	#23
Boris_Akunin Veteran Member Join Date: Aug 2012 Location: Bremen, Germany Photos: Gallery Posts: 674 Original Poster	I noticed that the UV was starting to bleach out the black finish on the Minolta... that shouldn't happen anymore:

11-22-2014, 04:58 PM	#24
LensBeginner Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 4,696	Originally posted by Boris_Akunin I noticed that the UV was starting to bleach out the black finish on the Minolta... that shouldn't happen anymore: An interesting side effect... And then they said that tin foil hats are useless...

11-22-2014, 05:03 PM	#25
Boris_Akunin Veteran Member Join Date: Aug 2012 Location: Bremen, Germany Photos: Gallery Posts: 674 Original Poster	Originally posted by LensBeginner An interesting side effect... And then they said that tin foil hats are useless... The change was only visible at the front of the lens (directly exposed to the UV lamp), so UV-C exposure was way beyond normal sunlight-levels.

01-04-2015, 06:51 PM	#26
Boris_Akunin Veteran Member Join Date: Aug 2012 Location: Bremen, Germany Photos: Gallery Posts: 674 Original Poster	Regarding the unwanted effects of UV-C, here's how much my Minolta MC 28/2.5 changed (left: MD 28/2 for comparison): Before: After 3 weeks of UV-C (>130w/m²):