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Dust, separation or fungi?

Started Oct 28, 2015 | Questions thread
brightcolours Forum Pro • Posts: 15,885
That is some kind of dust/contamination.

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.

Bubbles in glass do not look like that (and modern lenses do not have bubbles in glass much anymore). And fungus usually starts in a few places and grows from there.

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).

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