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Is this fungus?


Jannik Tesch
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Good day community,

is this fungus?

And if so, is it a danger for my other lenses? I heard it is contagous, but I don't know how much? Can I keep this lens in a box in the same room or do I have to get rid of it as soon as possible?
Never had to deal wirh fungus before.

Thanks in advance,
Jannik

fungus.jpg

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  • 2 weeks later...

It looks like fungus to me. I was loaned a couple of Cooke (Taylor Hobson) lenses which were fungussed. In an ideal world, infected lenses should be stored separately from known good lens sets.

Whilst the fungus is contained within the infected lenses it will migrate to the outside due to expression of air when the focus group moves. Your hands may then move the infection to other lenses.

If it has not been left too long, the lenses are recoverable but internal elements may need to be polished and recoated because the fungus will have etched into the coatings.

I am not sure whether the old Cookes had anti-reflection coatings on the internal glass, maybe just on the front and rear glass. 

If you are not sending the lens for repair/service, it may be best to bag it and give your hands a good wash in vinegar then water.

That lens is worth keeping and having treated, sooner rather than later. If it is a Cooke, especially Series II, it will still have considerable value, even in that state. Other ARRI Standard/B-Mount lenses are worth saving as well.

You can stall the fungus by uncapping the lens and letting direct sunlight fall into it for several days or set up a UV lamp to do the same job. 

If you are going to throw it out, don't. Please send it to me. 

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It’s not entirely clear to me whether that is fungus or cleaning marks to be honest. Fungus tends to look like spindly tendrils, not linear. But it could be.  Some examples I’ve cleaned recently:

510F54C3-2B25-41E7-ACF3-8C209403565E.thumb.jpeg.249c4de89db4419d64e11f03af5b54f6.jpeg5B2013A8-F9C1-430E-9760-8736210D040F.jpeg.e7e651f5b6cb243689b9718c13357f31.jpeg

It can be slowed with sunlight or UV, or opened up and cleaned off. Sometimes after cleaning it might leave a mark where it has etched into the coating, but that usually has minimal effect on the image, unless a large portion of the surface has been etched.

I’m not convinced it will automatically spread to other optics. I’ve had fungus lenses stored in the same room as other lenses and never had that problem come up. The spores exist naturally everywhere, but only start to really grow in dark, humid or moist environments. If you’re concerned, I would just leave it on a window sill in the sun for a while. And don’t store any gear where it’s dark and dank. 

 

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Dom Jaeger. I agree with you that it will not automatically spread within a population of stored lenses so long as that storage as you point out is not favourable to help fungus grow. Some lenses like the big Sigma zooms, physically breath in and out through the back end when the extending zoom barrel moves out and in. Fungus spores are more likely to get inside one and come right on out if an infected lens zoom is operated. A 50-500 I have was a mess. It was also a nightmare to dismantle and clean. I also discovered what the noise and slightly baulky motion was. A slot cam follower had pulled its securing screw loose. So being prompted by the fungus to open the lens up was fortunate in a way. 

Edited by Robert Hart
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Hi Robert and Dom, thanks for your answers and insights!

I'm sure it is fungus, you can see it better on the second photo above and on the upper right corner of the hot spot. Also these longer marks in the first picture are on the inside glass elements, so I guess they are unlikely to be cleaning marks(, which are commonly on the front and rear glass, right?)
Also when I looked inside the lens with light it looked much more like Dom's example images. I just did not manage to perfectly capture it.

@Robert Hart It's not a Cooke, it's an old Angeniex Zoom. I will use it to train to disassemble and clean a lens, when I have free time 🙂

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If you are going DIY with the Angenieux, take care matchmark everything you take off. It is vital to note and mark exactly where in the rotation when unscrewing the front barrel off the focus helicoid that it comes off. To be sure where in the rotation it finally detaches, put one matchmark on the main assembly first, then as you unscrew the front barrel, draw forwards so that when the last thread lets go you will observe exactly when it releases and pulls away forward. That's where you should start the thread when you reassemble. Immediately offer the front barrel back to the main body and make the second matchmark on the front barrel. There can be several starting points with helicoids. They are a mongrel to get started. Getting it wrong, then having to start over several times until you find the correct one can be extremely frustrating.

Edited by Robert Hart
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