pgk Posted July 6, 2017 Share #21 Posted July 6, 2017 Advertisement (gone after registration) It's easy to prove if it's a failure, but success, that's more difficult. Basic testing: research a common fungus killed by UV and obtain some to test with - in most places you should find that there are local experts who may be able to help you with this. Link to post Share on other sites More sharing options...
Advertisement Posted July 6, 2017 Posted July 6, 2017 Hi pgk, Take a look here B+W UV-PRO Premium Anti-Fungus Light. I'm sure you'll find what you were looking for!
jaapv Posted July 6, 2017 Share #22 Posted July 6, 2017 A high-intensity UV Most likely, but being an LED it *could* be quite efficient at emitting light at a narrow wavelength band, but they give no information about the wavelength range or the LED intensity. Also, it gives a wavelength of less than 300nm and a time of 2 min after which the unit shuts off. Given glass transmits roughly sweet f-all at wavelengths less than 300nm I'd be concerned by the time, especially for lenses with a lot of glass. But hey, at US$350 I'm not going to use it. A high-intensity UV source is not something that should be in amateur hands, so it is wise to limit the gizmo. Link to post Share on other sites More sharing options...
Soden Posted July 6, 2017 Share #23 Posted July 6, 2017 Basic testing: research a common fungus killed by UV and obtain some to test with - in most places you should find that there are local experts who may be able to help you with this. That's true, if you can isolate the cause. Simply by keeping the lens in a dry box adds variables. Link to post Share on other sites More sharing options...
Soden Posted July 6, 2017 Share #24 Posted July 6, 2017 A high-intensity UV A high-intensity UV source is not something that should be in amateur hands, so it is wise to limit the gizmo. Hmmm, should I use a UV filter to protect the lens? I already had cataracts so that's no longer a concern. Philips provides a UV sanitizer for its sonic care toothbrush, I have the feeling its output will be similar. Link to post Share on other sites More sharing options...
stephengv Posted July 6, 2017 Author Share #25 Posted July 6, 2017 Thank you for your professional insight. Will the UV damage the lens? It's actually total accumulated dose that kills the fungus. You need to deliver the right number of photons, either with a very short high intensity burst, or a weak source with a long exposure. In reality it's better to deliver the dose quickly, so the organism doesn't have enough time to repair itself before the next photon hits it. The long and slow approach comes from yesteryear when high intensity UV sources were confined to large scale science facilities. (I'm currently putting the finishing touches on a paper about X-ray induced radiation damage on small organisms with several different preparation methods - it's pretty complicated when you get deep into it) Link to post Share on other sites More sharing options...
stephengv Posted July 6, 2017 Author Share #26 Posted July 6, 2017 I emailed and message three retailers here in South East Asia and Schneider Optics USA. According to Schneider USA: "We do not sell that product in the US. It does not eliminate fungus that is already present." - It appears that it is made by B+W but not sold in the USA. According to Digital Rev (HK International retailer): "xxx we can confirm that it is manufactured by B+W." According to Cathay Photo (Singapore retailer): "It's a B+W product." According to TK Foto Technic (Singapore retailer): "Yes this is an original product by B+W" I doubt it. Does anybody know for sure? Link to post Share on other sites More sharing options...
stephengv Posted July 6, 2017 Author Share #27 Posted July 6, 2017 Advertisement (gone after registration) Most likely, but being an LED it *could* be quite efficient at emitting light at a narrow wavelength band, but they give no information about the wavelength range or the LED intensity. Also, it gives a wavelength of less than 300nm and a time of 2 min after which the unit shuts off. Given glass transmits roughly sweet f-all at wavelengths less than 300nm I'd be concerned by the time, especially for lenses with a lot of glass. But hey, at US$350 I'm not going to use it. I found one at Ebay for around $110. Its still expensive, however the repair cost will be a lot more. Link to post Share on other sites More sharing options...
stephengv Posted July 6, 2017 Author Share #28 Posted July 6, 2017 I had the rear group from a 35mm Summicron v.4 re-cemented after it had delaminated a couple of years ago. The friend who got this done for me is fortunate in having access to a specialist lab (long story but they really do know what they are doing and produce very exotic and expensive lens systems for highly specialised users). The comment which came back was that they had had to use a high dose of UV to cure the cement due to the high UV absorption of the glass in this rear group. So whilst I doubt damage (although earlier, balsam cemented lenses may be a concern if UV affects balsam?) I'd also very much doubt any beneficial effect at low dosage. Thank you for this story. It appears that it won't damage the lens. Link to post Share on other sites More sharing options...
stephengv Posted July 6, 2017 Author Share #29 Posted July 6, 2017 True at $350 no, but at $120 I'll give it a shot. I have one on order. The big question is how to prove its effectiveness. It's easy to prove if it's a failure, but success, that's more difficult. The question of authenticity, I'll judge on build quality, when it arrives. I also ordered one. Roughly the same price as $120. Although I already use a dry cabinet, I'm still anxious of possible fungus infection of my lens. I have a Canon F1-N which sits in my dry cabinet most of the time, it was infested by Fungus in the viewfinder. Note that I expose all my camera and lens in direct sun light, at the very least once a month. Link to post Share on other sites More sharing options...
laowai_ Posted July 6, 2017 Share #30 Posted July 6, 2017 Has anyone tried this? Is this really made by B+W? Thank you. Here is a link from Leica Rumors https://leicarumors.com/2016/04/26/this-bw-uv-pro-premium-device-should-prevent-lens-fungus-leica-mount-compatible.aspx/ Made is a relative term. I am sure Schneider (B+W) does not own an GaN fab to manufacture UV-LEDs. Schneider/B+W's contribution would be more of an integration, packaging, marketing, distribution and support job and I bet that's also where the money is. Link to post Share on other sites More sharing options...
laowai_ Posted July 6, 2017 Share #31 Posted July 6, 2017 Sunlight has plenty of UV, but less reaches us as the humidity increases (water absorbs UV) and it's free. So the best way to not get fungus is to use the equipment regularly. There are other cheaper sources of UV light too. You could get a UV water sanitiser and put it on the lens covered by aluminium foil (you don't want to get the dose). It'd be cheaper and you can use it for water too! In the end it's just a UV LED and a cover to stop the light escaping. Looks to be battery powered too so it can't be putting out that much power. I would have thought that by now lens manufacturers would have included an anti fungal agent on their coatings... Let's say that would be USB powered. LEDs are current sinks with a resistance let's jus say 5 Ohms, the USB port gives you max. 500 mA. Another bold assumption: EO conversion efficiency is 80%, so we are talking at most 1W or 30 dBm optical power, probably a lot less. That's a decent amount of power, I would not like to shine this into my eyes. A popular way of "damaging" glass is to "write" gratings. This is often done with excimer lasers that operate at much higher power levels and you would need some form of phase coherence to boot. So, no worries about damaging the glass per se with this little device. Organic compounds in a lens assembly (if there are any) is a different story though. Link to post Share on other sites More sharing options...
jaapv Posted July 6, 2017 Share #32 Posted July 6, 2017 All Leica lenses since ca. 1950 are effectively filtered against UV light. I don't see this penetrating inside the lens. Link to post Share on other sites More sharing options...
michaelwj Posted July 6, 2017 Share #33 Posted July 6, 2017 According to Schneider USA: "We do not sell that product in the US. It does not eliminate fungus that is already present." - It appears that it is made by B+W but not sold in the USA. If it cannot kill fungus that is present then how is it supposed to inhibit its growth? The only way it could do that would be if it created ozone, which it doesn't. Link to post Share on other sites More sharing options...
pico Posted July 6, 2017 Share #34 Posted July 6, 2017 You guys were freaking me out. I just checked my storage area and it is 37% humidity, 65°F. All is good. Outside it is 95°F, 80% humidity in the tropics of MinneSnowta. Link to post Share on other sites More sharing options...
michaelwj Posted July 6, 2017 Share #35 Posted July 6, 2017 Let's say that would be USB powered. LEDs are current sinks with a resistance let's jus say 5 Ohms, the USB port gives you max. 500 mA. Another bold assumption: EO conversion efficiency is 80%, so we are talking at most 1W or 30 dBm optical power, probably a lot less. That's a decent amount of power, I would not like to shine this into my eyes. A popular way of "damaging" glass is to "write" gratings. This is often done with excimer lasers that operate at much higher power levels and you would need some form of phase coherence to boot. So, no worries about damaging the glass per se with this little device. Organic compounds in a lens assembly (if there are any) is a different story though. 1W is a lot of last power, but this is just an LED lamp, so it's not AS dangerous. But yeah, I still wouldn't shine it into my eyes, or onto my skin for too long. Link to post Share on other sites More sharing options...
jaapv Posted July 6, 2017 Share #36 Posted July 6, 2017 If it cannot kill fungus that is present then how is it supposed to inhibit its growth? The only way it could do that would be if it created ozone, which it doesn't. Considering the whole thing it appears to me to be a complete waste of money. If even the USA branch of the manufacturer refuses to sell it because it does not work. How could it? Power too low for the duration of use, lenses filtered against UV light... The problem is proving it does not work, as the percentage of lenses that actually contract fungus is not very high. Link to post Share on other sites More sharing options...
jmahto Posted July 6, 2017 Share #37 Posted July 6, 2017 It seems that only effective solution is to use silica gel and keep it in a dry cabinet. A small bulb to dry the air also helps (I never used it). I also read someplace about using the Sun (it has UV rays) to kill off any fungus. If the humidity is persistent then this won't be an option. It seems we are back to dry cabinet as only solution. Link to post Share on other sites More sharing options...
jaapv Posted July 6, 2017 Share #38 Posted July 6, 2017 I don't even believe this sun myth. It will help I'm sure, but only by drying out the lens. Link to post Share on other sites More sharing options...
michaelwj Posted July 7, 2017 Share #39 Posted July 7, 2017 I don't even believe this sun myth. It will help I'm sure, but only by drying out the lens. I think fungus dies at above 65 degrees C? It's get pretty hot between the elements! Link to post Share on other sites More sharing options...
stephengv Posted July 7, 2017 Author Share #40 Posted July 7, 2017 I don't know how true this video is, but check it outhttps://www.youtube.com/watch?v=Uc2oAoK1MUs Link to post Share on other sites More sharing options...
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