Fungus in a lens

[kiwidad]

Advertisement (gone after registration)

How quickly can it grow?

I have a 28mm Leica lens that has fungus. To tell the whole story I purchased it from a Leica store used having had a Leica CLA performed in 2023.

i dint closely examine it when I purchased it given it came from a reputable source. 
today I am told it has fungus on the inner elements and I question this as being less that 6 months old. Lens while in my possession has not exposed to heat or cold or moisture , rain etc

so my question is …. Should argue this point with the Leica dealer, Leica themselves if it under the 24month service warranty or panic about my other gear and get dry storage unit?

Edited July 18 by kiwidad
Typo

[GFW2-SCUSA]

First thing I'd do is make certain it has fungus. If it does I would return it to the selling store for a refund. My experience with fungus  is that it is very difficult to get rid of and can etch the glass.  Don't panic until you know for certain it is fungus! 

My "cure" for the fungus was putting the lens in direct sunlight, wide open for a couple of days. The UV killed the fungus. Most of it went away, but the lens is not as good as new. It was a Nikon lens, not that it makes a difference. 

[gbealnz]

Agree with the reply above, establish first it is or isn't fungus.

If it is (and if it were me of course) I'd send it back, or have a conversation with them. It's one of those things that once you've seen it, you can't un-see it. It would annoy me.

[jankap]

5 hours ago, GFW2-SCUSA said:

My "cure" for the fungus was putting the lens in direct sunlight, wide open for a couple of days. The UV killed the fungus. Most of it went away, but the lens is not as good as new. It was a Nikon lens, not that it makes a difference. 

But be very careful not to light a fire.

Edited July 18 by jankap

[pgk]

7 hours ago, kiwidad said:

How quickly can it grow?

This depends. Basically fungus appears to like dark, warm, humid conditions. If you have stored it in such conditions it will grow at its fastest. But fungus, like any other living thing, also requires nutrients and I am very doubtful that the coatings on optical glass offer anything other than traces of what is needed, so in general living on lenses is unlikely to be a good fast growing habitat so fungus is unlikely to grow quickly here. All of which suggests to me that unless you are storing the lens in a very humid, warm dark place then its more likely (IMO) to be a longer term problem and the lens may well have had traces of fungus when you bought it. If no other lenses have any fungus this again would support the idea that this particular lens was already infected. If it has a good warranty you should take it back and argue the point if there are any objections.

Do make sure that it is fungus and not something else like separation though, which can occasionally look similar.

[jankap]

How can he make sure, that it is fungus? By loading a smartphone photo here?

[kiwidad]

Advertisement (gone after registration)

these is what I see

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[jankap]

Did you clean the lens surfaces? Please, be careful, if you do it now. Also, the surface at the back?

This is my Canon 28mm f/2.8 from 1968(?).

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

 

Edited July 18 by jankap

[jankap]

I only clean my lenses for dust, with a blower. In your case, even I would use something, that is wet. If it was my lens, I would here take a spectacles cleaning tissue. Wipe very carefully, without pressure.

 

Edited July 18 by jankap

[kiwidad]

Lens was cleaned externally I am tol.

lens should be back in my possession today. Hopefully with the paperwork showing the 2023 CLA date.

i understand the CLA has a 2 years warranty but not sure about this.

[pgk]

1 hour ago, kiwidad said:

these is what I see

That does not look like fungus to me - fungus usually shows as 'tendril-like' growths. It could be the result of severe condensation which has dried out and left residue for some reason, or some other material which has somehow got inside the lens. It looks as though the lens needs a clean including the internal lens surfaces. A better way of photographing it might be to use 'dark field illumination' by putting a light source under it then using a dark disk between the light and the lens so that the light is effectively a ring light and illuminates from the edges. This will show anything up as lit but on a darker background which should make it easier to see.

[wizard]

vor 1 Stunde schrieb kiwidad:

these is what I see

Does not look like fungus to me either, more like condensation (if it is inside the lens) or some cleaning agent residue (if on the outer surface of the rearmost lens element). Take a clean cloth and a drop of water and gently wipe the outer surface of the rearmost lens element and see if what you see changes. If what you see is inside the lens, it has to go to a professional.

[sometimesmaybe]

18 hours ago, kiwidad said:

these is what I see

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

agree that's not fungus. it does look like drying marks. maybe they did a slightly sloppy job with the CLA when cleaning that element 

[jakontil]

Definitely not fungus

[kiwidad]

43 minutes ago, sometimesmaybe said:

agree that's not fungus. it does look like drying marks. maybe they did a slightly sloppy job with the CLA when cleaning that element 

I wondered.... the dealer I bought it from said it had no fungus, but if this isnt fungus then??? 

My eyes not really up to the task of checking and maybe not a good technique either. I looked at the lens tonight and I can't see this. 

As I understand it CLA have a 24 month warranty, wondering what the odds of me getting Leica to redo it 5 months after warranty expired. It actually had a lot done more than just CLA when it went to Leica. the paperwork says they spent 4.370 hours, repaired focusing and cleaned it and fixed helens head. I do wonder if that the remnant of a German fingerprint lol.

When shooting I also see no problems at all. contrast and sharpness are great just like when I bought it back in February.

 

[250swb]

If only there was a sticky with the title 'How to photography fungus and lens separation'.

I can't tell from the photographs, without a proper view I veer slightly away from fungus, or separation, but something reminds me of the marks condensation leaves after it's formed on the residue of a cleaning chemical etc.

 

[earleygallery]

You bought the lens used, less than 6 months ago from a Leica store who also told you that the lens had a CLA in 2023? 

Who told you it has fungus? Who - and what have they been doing with the lens? 

Where does the 24 month warranty come from? 

 

[kiwidad]

6 hours ago, earleygallery said:

You bought the lens used, less than 6 months ago from a Leica store who also told you that the lens had a CLA in 2023? 

Who told you it has fungus? Who - and what have they been doing with the lens? 

Where does the 24 month warranty come from? 

 

I tried to trade the lens in with other g ear for a Summilux 28mm and the store refused to take it and sent me the pictures I posted here.

I understood Leica give a 24 month warranty on CLAs and repairs and this appears to have been in both categories (I have a copy of the Leica invoice)

I sent the images to the two repair people I use and one slide today saying he thinks it is mould. This has fueled my GAS and I am looking at dry cabinets!

[earleygallery]

I agree with others that the images you posted don’t look like fungus but in the circumstances it’s probably best to explore the warranty option. 
 

Worst case scenario keep it and use it, I have some very ropey looking lenses that actually perform superbly.

[Advertisement]

Hallo,

Look here: Leica M

[jankap]

On 7/20/2025 at 1:03 AM, earleygallery said:

Worst case scenario keep it and use it, I have some very ropey looking lenses that actually perform superbly.

There is so many dirt in the lens, that f/2.8 is correct in the theoretical sense only.😜