Issue with second hand EF 300 2.8 IS..Thoughts???

[Viggo]

Hmm, anyone have a link to that "spider-webbing" ? That just sounds like what I saw in my 200...

Many types of advanced fungus have a stringy spiderwebish type look and is a certain differentiator between bad dust and fungus.

https://www.google.com/search?q=lens+fungus&client=firefox-a&hs=SkD&rls=org.mozilla:en-USfficial&tbm=isch&tbo=u&source=univ&sa=X&ei=lZxoUu_PKoahkQfrwICIAQ&ved=0CCsQsAQ&biw=1265&bih=681

Thanks ! That is def not what I see on the 200, it's like it's around the edges so that the whole element is displaying some weird pattern along the edges.