Is this fungus?

[trevor_newman1]

<p>Hi all,<br>

So after a wonderful day with my new (used) lens at the Getty I switched lenses and noticed these odd bubbles/streaks along the circumference of the back element. I am not quite sure what it is. I don't think it's fungus but I have never had a lens with fungus. What do you all think...regardless this lens rocks.</p><div></div>

[trevor_newman1]

<p>oh, they also appear to between elements and not right on top.</p>

[rparmar]

<p>Doesn't look like fungus, which is more of a random filament shape. I would say it's just cleaning fluid residue except if it's between elements maybe it indicates separation? Someone with more experience should be able to help.</p>

[michael_kuhne]

<p>Appears to be some streaks typical of a lens having been cleaned, along with some reflections. Does not look like something that would affect optical quality.</p>

[jpo3136b]

<p>Maybe, but if it is it's in the earliest of stages. Fungus will have a distinctive opaque light-gray to brown appearance. When it's advanced, it will look like it's kind of spider web-like. Usually, it's at that stage that it begins to cause some damage to the glass. In the meanwhile, it can look like a grayish dust that you cannot clean off. </p>

<p>I don't have much experience with this, but I once purchased a used 16mm camera that was badly corroded; the lens elements had a serious fungus problem that required repair and cleaning. In that instance, it was so bad, that even a casual look through the lens revealed that the glass appeared dim and hazy, regardless of lens setting. That lens assembly was about sixty years old. </p>

<p>My guess is that it may only need a good cleaning, regardless of what it is. </p>

[pbarnes]

<p>Trevor, whatever it is, it won't hurt to give it a dose of UV radiation by sitting it in the sun for an hour or two - if it is fungus, I am told that UV will kill it. Won't go away, but won't get worse.</p>

[jim_b9]

<p>Doesn't look like fungus to me.<br>

Here is what lens fungus typically looks like:</p>

<p><img src="http://www.techarp.com/article/Used_Lens_Guide/fungus_01.jpg" alt="" width="300" height="200" /></p>

[randall ellis]

<p>It's neither separation nor fungus. Fungus looks just like the image provided above, and separation looks very different - a solid arc of what appears to be an air bubble sandwiched in the glass. Regardless of what it is, it's way too far out at the edge to cause any problems even wide open...</p>

<p>- Randy</p>