Fungus

[kelly41]

Hi all can anyone recommend someone to remove the fungus from my beercan lens, the fungus appears to be between the 2 front lenses also does anyone know how much this usually costs

thanks

[Mark K]

I guess it is the end of your lens. I have some on my 20-35/3.4-4.5. I paid a lot to remove thess fungi but at the end the lens became more hazzy.
I sent my Sigma 28-70/2.8 EX to Sigma and they only recommended me to change the entire lens system.

[Greg Beetham]

I don’t like your chances of getting it fixed economically either. It’s a specialized job for optical experts to separate the doublet with the right solvent and temperature then clean them up without damaging them (some internal elements with high grade LD glass are a bit soft) and then cement them back together (centred) with the correct optical cement for the application (thermal coefficient/humidity/vibration/impact resistant etc.) without any microscopic air bubbles in a dust free environment. I’d say there would be some optical place that could do it (properly) but you will have to do some searching in your location to see what you can find.
Greg

[kelly41]

Well its in for repair
they seem to think it can be saved as it was only very slight, luckily its not costing a lot either

will post some pics when i get it back

[agorabasta]

Well, if the contamination is small, it should not affect the image much. So you could simply stop the fungus by killing it, and that's easily done with some X-ray machine (frequent flying helps, too). That's if it's really fungus, which is not the case quite often as there are quite a few non-biological life-like processes that may take place very well on those surfaces/coatings...

[bakubo]

Well, if the contamination is small, it should not affect the image much. So you could simply stop the fungus by killing it, and that's easily done with some X-ray machine (frequent flying helps, too). That's if it's really fungus, which is not the case quite often as there are quite a few non-biological life-like processes that may take place very well on those surfaces/coatings...

I have an A-mount Tokina 400mm f/5.6 AT-X that I bought in Tokyo in 1992. It has probably only been used to take less than 50 photos. Looks brand new. I remember using it to take 3-4 photos in 1999 and then didn't look at it again until I got my KM 7D in 2005. I pulled it out of the camera bag in the closet and discovered that internal elements appeared to be fogged up. I asked about it on photo.net:

http://photo.net/filters-bags-tripods-a ... rum/00BTJ2

The most likely explanation in my case was that there was a breakdown in the lens "bonding agent".

[edrice]

The likelihood of fungus getting into glue between the doublets would probably be fairly rare. When zoomed or focused most lenses will suck air in and out and spores can be sucked in and land on elements and if the environment is humid, spores can grow. In a dry climates, spores may do nothing but sit there. Spores are universal.

In most cases it's fairly simple to remove it if the fungus hasn't eaten away at the coatings. I've done a couple myself in years past, one being a Minolta MD 100-200mm and the other was an MD 28-85 (if I remember right - long ago). An application of cold cream to the lens elements was successful in removing the fungus. Subsequent tests with film showed no apparent effects, so they can be effectively restored.

About a decade ago, the going rate for removing fungus was less than about 100$ US. It's a fairly simple operation to disassemble the lens and clean it. I've heard warnings that elements would have to be recalibrated with a collimator but I never saw any problems with this or any way to adjust the elements in their seats. The lenses would have otherwise been useless anyway, so I tried it and it worked fine. The coatings on the 100-200 had been lightly etched near the edges but it had no effect on photographic results that I could see.

I avoid any kind of heat with lenses especially leaving them in sunlight as this can cause lubricants to flow in unwanted places, like blades. I don't know if that is still a problem with more modern lenses but it was a real problem in the past, especially with certain lenses.

[Greg Beetham]

If the fungus is just on the outside of an element then it’s a straightforward matter to clean (and hope the fungus hasn’t etched the element) compared too a cemented doublet that’s gone cloudy between the cemented elements. It’s either because of a partial delamination of the cemented doublet and then fungal penetration or fungus just penetrates the cement and causes it too go cloudy, take your pick, but I have seen lenses afflicted in this way. And there is no respect by the fungus for expensive lenses either, I saw at an auction once amongst other things a large Nikkor that had clouded up. I didn’t see what was bid on it as I had lost interest. I also have seen the rear doublet on a Tamron 200-500 clouded up. Most doublets are sealed with acrylic lacquer on the edge now but there is always the possibility of scratching the paint during assembly.
Greg