24-70 f/2.8 L II front coating peeling off?

[traveller]

I have a friend whose 24-70 f/2.8 L II is currently with Canon, as the front coating appears to be separating from the glass of the front element. Has anyone else experienced anything like this with any of their lenses and if so, how did Canon respond?

[Marsu42]

I have a friend whose 24-70 f/2.8 L II is currently with Canon, as the front coating appears to be separating from the glass of the front element. Has anyone else experienced anything like this with any of their lenses and if so, how did Canon respond?

Not if *that* would happen with Tamron, what would the community say :-p (remembering the s***storm over the Internet after a front element in one 24-70vc dropped off...). With Canon, I guess it's an hearsay isolated example of product failure, probably due to doubful user handling, that is to be expected with mass production and just has to be replaced under warranty :->

[neuroanatomist]

It's certaily possible for the coatings to become damaged or to delaminate.  If the outer protective layer(s) are damaged (by physical impact like an object hitting the front element or a scratch caused by larger particulates on the lens when it's rubbed with a cleaming cloth), moisture can penetrate the layers of coatings, and some of the antireflective layers are quite susceptible to moisture damage (not even water on the lens - humidity is enough).  Use of inappropraite cleaning solution can damage coatings, even Scotch tape can cause microscopic lesions of the surface.

remembering the s***storm over the Internet after a front element in one 24-70vc dropped off...

It wasn't just one (and it was the second element), and Roger provided a good reason for its occurrence.

http://www.lensrentals.com/blog/2012/09/tamron-24-70-f2-8-vc-issue

Incidentally, he praised Tamron's handling of the issue.

[Don Haines]

I have a friend whose 24-70 f/2.8 L II is currently with Canon, as the front coating appears to be separating from the glass of the front element. Has anyone else experienced anything like this with any of their lenses and if so, how did Canon respond?

Many years ago I had that problem with a lens and the coatings disintegrated.. It was a 50F1.8 so it was not even worth the cost of shiping it to be looked at... The camera had been outside all day at -65C and when it warmed up the coatings fell apart. I think it was due to the severe cold.... Did your lens get excessively cold?

[traveller]

It's certaily possible for the coatings to become damaged or to delaminate.  If the outer protective layer(s) are damaged (by physical impact like an object hitting the front element or a scratch caused by larger particulates on the lens when it's rubbed with a cleaming cloth), moisture can penetrate the layers of coatings, and some of the antireflective layers are quite susceptible to moisture damage (not even water on the lens - humidity is enough).  Use of inappropraite cleaning solution can damage coatings, even Scotch tape can cause microscopic lesions of the surface.

Possible explanation, but it was quite widespread over the front element (sorry, I didn't think to take a photo at the time). At first, I thought it was just moisture, but it wouldn't rub off; it also didn't look like your usual scratches: they weren't thin lines, but fat and speckled. It's strange because it's his newest lens (less than a year old) and none of the others are in this sort of state, despite similar usage.

UPDATE: I've just had a 'phone call from him (whilst typing this); Canon are blaming this on "excessive cleaning". The lens is just over 12 months old and apparently been cleaned with only a microfibre lens cloth... Time to buy UV filters for my lenses? Oh rats, the good ones are multi-coated too!!! 

[privatebydesign]

I have a 100L Macro which I believe has the same nano coating, not long after I got it I noticed a "blemish" in the coating, it wasn't there when I got the lens. I tried to rub it off but it wouldn't budge, indeed it looked like a pocket of air, or bubble in the coating, certainly it looked to have the third dimension or depth to the blemish. I was disappointed but was determined to either clean it off or get a new front element. With that attitude I set about really laying into "cleaning" it, basically I rubbed the sh-t out of it and did nothing but make many rub marks around the blemish. I was resigned to a new element. However before I sent it off I had my cleaning fluid out and tried one last time, voila, not only did the blemish disappear completely but also the "cleaning" marks all went as well.

Now I recount this not to make myself look like the dufus I was, but to point out that even when we are "certain" the coating is damaged, it might well not be, and further, I find it practically impossible to believe you could rub those nano coatings hard enough by hand to damage them, I know how stupidly hard I "cleaned" mine with zero ill effects.

[tron]

I have a 100L Macro which I believe has the same nano coating, not long after I got it I noticed a "blemish" in the coating, it wasn't there when I got the lens. I tried to rub it off but it wouldn't budge, indeed it looked like a pocket of air, or bubble in the coating, certainly it looked to have the third dimension or depth to the blemish. I was disappointed but was determined to either clean it off or get a new front element. With that attitude I set about really laying into "cleaning" it, basically I rubbed the sh-t out of it and did nothing but make many rub marks around the blemish. I was resigned to a new element. However before I sent it off I had my cleaning fluid out and tried one last time, voila, not only did the blemish disappear completely but also the "cleaning" marks all went as well.

Now I recount this not to make myself look like the dufus I was, but to point out that even when we are "certain" the coating is damaged, it might well not be, and further, I find it practically impossible to believe you could rub those nano coatings hard enough by hand to damage them, I know how stupidly hard I "cleaned" mine with zero ill effects.

Thanks for the info. This is reassuring. I remember  my EF 14mm f/2.8L II which had (or has I am not 100% sure right now) a softness that could not be removed. Anyway it turned out that although it could not be removed it could be ... moved!  So it looks like a similar case 

[TexPhoto]

Some photos of what is happening would certainly help. 

[Mt Spokane Photography]

I have a friend whose 24-70 f/2.8 L II is currently with Canon, as the front coating appears to be separating from the glass of the front element. Has anyone else experienced anything like this with any of their lenses and if so, how did Canon respond?

Are you saying that the nano coating on the glass is pealing?   The process of applying the nano coating is pretty high tech, Is it possible that he used some sort of solvent to clean it?
 
http://www.canon.com/technology/s_labo/light/003/03.html

[JustMeOregon]

Of course I have no idea if it's related, but I recently accidentally destroyed a pair of eyeglasses by washing them with 99% isopropyl alcohol. They peeled like 30-year paint on the sunny-side of a barn...

[Mt Spokane Photography]

Of course I have no idea if it's related, but I recently accidentally destroyed a pair of eyeglasses by washing them with 99% isopropyl alcohol. They peeled like 30-year paint on the sunny-side of a barn...

Yes, its common on eyeglasses, they are usually plastic, so the coating is not flame sprayed (Vapor Deposited) at extreme high temperatures like glass camera lenses.   That process costs more than a high end pair of glasses, and has been extremely reliable, so its unusual to have this happen.  There can be manufacturing defects, or issues using the wrong cleaner.

[traveller]

UPDATE: I've just heard back from my friend, the technician at the service centre told him that it is very unusual for the lens coating to peel in this way after such a sort period of time. Usually they would expect to see signs of very heavy usage on the body of the lens in these cases. The service centre have been instructed to replace the front element under warranty and send the damaged front element back to Canon for further investigation. Meanwhile it looks like my friend will have his repaired lens back tomorrow.
I'd say this might be a case of an isolated manufacturing defect. I don't think it's anything to worry about if you own this lens, but worth knowing in case it does happen to you.

[tron]

Thanks for the warning. I always use filters so normally I do not watch what happens between the filter and the lens but I will give a look every few months.

[Mt Spokane Photography]

UPDATE: I've just heard back from my friend, the technician at the service centre told him that it is very unusual for the lens coating to peel in this way after such a sort period of time. Usually they would expect to see signs of very heavy usage on the body of the lens in these cases. The service centre have been instructed to replace the front element under warranty and send the damaged front element back to Canon for further investigation. Meanwhile it looks like my friend will have his repaired lens back tomorrow.
I'd say this might be a case of an isolated manufacturing defect. I don't think it's anything to worry about if you own this lens, but worth knowing in case it does happen to you.

They do a large batch of them at once.  It is a very critical process, but its hard to understand why it would not affect a whole production run, or at least a whole tray of them, unless someone happened to somehow get just one lens dirty, or the cleaning process missed one lens.
 
You can get some info about the process here;
 

http://youtu.be/qzpt49qq6v4
	Small | Large

 
 

[Don Haines]

UPDATE: I've just heard back from my friend, the technician at the service centre told him that it is very unusual for the lens coating to peel in this way after such a sort period of time. Usually they would expect to see signs of very heavy usage on the body of the lens in these cases. The service centre have been instructed to replace the front element under warranty and send the damaged front element back to Canon for further investigation. Meanwhile it looks like my friend will have his repaired lens back tomorrow.
I'd say this might be a case of an isolated manufacturing defect. I don't think it's anything to worry about if you own this lens, but worth knowing in case it does happen to you.

That is a good, responsible  reaction from the manufacturer.... S___ happens, they can either learn from it or deny it... looks like they chose to learn.