Dust, separation or fungi?

Hello all, I have quite a conundrum and would like better trained eyes to help discern just what is inside my lens.

I just bought a 70-200 f/2.8 IS lens (Canon, MK I) used, and was performing checks on the lens. On the outside the lens seems to be ok, but when inspecting the inner elements I came across some weird dots on (in?) the glass which seems to be almost in the middle of the lens.

At first I thought they looked like bubbles, as they seem to be very evenly spread. My next thought was mold (gasp), but in my experience, mold tends to grow from the sides and looks like little tendrils. Granted, I've seen that mold can look like spots too, but not quite like these.

Anywho, I leave you with the images I took in a hurry right now. In the worst case scenario, I plan to get the lens into maintenance or for appraisal with Canon.

Thanks.

In this image, you can see that some spots are bigger, but those are out of focus (it seems they are on two contiguous elements).

To me, it looks like little bubble imperfections in the glass. I remember seeing a very similar photo and discussion of this years ago wrt the 70-200 f/2.8L (non-IS? or IS I, maybe the same lens   ) but cannot bring it up with search. I think it was determined to be a non-issue in the optical performance of the lens (but I could be wrong).

here's a similar discussion on the TS-E 24 f/3.5L II:

http://www.dpreview.com/forums/thread/2825122#forum-post-35637678

Kurono wrote:

Hello all, I have quite a conundrum and would like better trained eyes to help discern just what is inside my lens.

I just bought a 70-200 f/2.8 IS lens (Canon, MK I) used, and was performing checks on the lens. On the outside the lens seems to be ok, but when inspecting the inner elements I came across some weird dots on (in?) the glass which seems to be almost in the middle of the lens.

At first I thought they looked like bubbles, as they seem to be very evenly spread. My next thought was mold (gasp), but in my experience, mold tends to grow from the sides and looks like little tendrils. Granted, I've seen that mold can look like spots too, but not quite like these.

Anywho, I leave you with the images I took in a hurry right now. In the worst case scenario, I plan to get the lens into maintenance or for appraisal with Canon.

Thanks.

In this image, you can see that some spots are bigger, but those are out of focus (it seems they are on two contiguous elements).

Looks like fungus to me.  Fungi secretions will etch the glass coatings and you can't fix it.  If you just bought that lens, you may want to return it if you can.  I always check a lens with a flashlight before buying.  Good luck.

I would err on the side of caution and assume fungus.

If I google "fungus spots on a lens" without the quotes then hit the images tab I see a lot of images that resemble that.

I once had a lens come to me with obvious fungus and a smell that I could only describe as rotten takeaway. (Not all fungus smells but if sniffing the lens makes you cringe that's a good sign). Cost me a bit to post it back but I got the rest of my money back.

Good luck.

Kurono wrote:

Thanks, everyone. I went with the cautious route and took it to a Canon certified center. Turns out it indeed was fungus, but a very light case of it. The maintenance will be expensive of course (about $150), but most will be covered by the seller (I'll still pay $50, but I guess it's worth it for the lens). No elements had to be replaced, so I guess I kind of lucked out on that.

You sure did. I lost an L lens to fungus one time, not fun!

Kurono wrote:

Thanks, everyone. I went with the cautious route and took it to a Canon certified center. Turns out it indeed was fungus, but a very light case of it. The maintenance will be expensive of course (about $150), but most will be covered by the seller (I'll still pay $50, but I guess it's worth it for the lens). No elements had to be replaced, so I guess I kind of lucked out on that.

I'm glad you got it all worked out.

My 70-200 2.8 non is looks exactly like this. Canon has it and I received a quote to clean it was 414 total. They did not say on estimate if it was fungus or not. I guess my question would be is it worth paying that or just buy a 70-200 new. If it's fungus, is it possible that it will return at a later time ? I did purchase the lens used a year ago, entirely my fault.

Bigd

bigd3030 wrote:

My 70-200 2.8 non is looks exactly like this. Canon has it and I received a quote to clean it was 414 total. They did not say on estimate if it was fungus or not. I guess my question would be is it worth paying that or just buy a 70-200 new. If it's fungus, is it possible that it will return at a later time ? I did purchase the lens used a year ago, entirely my fault.

Bigd

The OP hasn't posted anything on DPR since this thread 5 years ago, so doubtful that he/she will see your response (and if they did it is about 4½ years too late) 

Colin