Is this a fungus spot on the rear element of this EF 24-70 2.8

hotdog321 wrote:

Marc dbr wrote:

How does fungus affect the lens? and how is it caused?

I'm no expert, but it slowly eats the multicoating creating a bit of flare. It can slowly spread on the lens surface since it is alive. My biggest concern would be any other nearby lenses.

Moisture is usually the main culprit. I'm not sure how prone more recent lenses are to fungus--I hope the manufacturer changed the multicoating formula, but I have zero info.

yes, that would be a nightmare for an expensive lens owner! unfortunately, there aren't lots of effective and compelling info available how to remedy this thing!

I picked up a 20D and 17-85 for free because the lens has fungus on inner elements. I tossed the lens and washed and Lysoled the caps. Should I toss the camera just in case?

Redring1 wrote:

I picked up a 20D and 17-85 for free because the lens has fungus on inner elements. I tossed the lens and washed and Lysoled the caps. Should I toss the camera just in case?

i wouldn't have tossed anything! i find it fun to open dead lenses and cams to play with the elements to see how they are made i do that to dead hard drives and other electronics and leave them on my desk! as an experiment, i would put a tiny bit of Colorax on the tip of a Q-tip and apply it on the "fungus" spot to see what kind of effect it'll have on the fungus and then that info (success/failure) could be shared with folks here as "fact". of course i am only talking about exposed elements ( front/rear)! it could be done to internal elements as well, only when outer element experience is done remember, the Clorax application should not be more than just a dab, only to cover the fungus spot!!!!

Good Idea but the lens went last week. So I wait and see on the body?

Ok I will lysol wipe down the body. the camera bag was one of my old ones but clean at the time, so I will rewash it. I picked this up for my kid to use when his hands can hold it.

Thank you to everybody who replied. I really appreciate it. I'll have to take it to a Canon service shop to have them clean it then.

Hi,

it looks fungus to me, but before you start with the fungus paranoia, some facts:

- There are about a million fungus spores per cubic meter. Don't waste your time trying to kill them, just do not create the environment to allow them to form a colony.

- Spores are extremely resistant, so even if you try to kill them, probably it won't work.

- The spores need two things to form a colony, food and water. Food is (inside the lenses) normally any fat residue. The coating is not food. Water is taken from the air.

So, I would have the lens cleaned.If no-one wants to clean it, you could do it yourself with an alcohol based cleaner (like the zeiss disposable cleaning wipes). There might be a residue that cannot be removed, and in some cases, there might be some damage to the coatings. After you clean it, it won't spread until the conditions to form a colony are back.

So, keep your lenses in a dry environment. And don't worry about putting this lens with the others, or waste your time trying to disinfect everything. The colonies can grow, but they cannot fly or jump from one lens to the other. Only the spores fly,and again, they need a proper environment to form a colony.

And btw, the spot in your lens is very small, I really doubt it will have any impact in your images, but clean it anyway, otherwise the colony can grow much bigger.

If there is anything not clear, please tell me. I'm not a native English speaker.

Cheers!

Thank you very much for your detailed explanation. Much appreciated!