"Ken Rosenbaum" wrote in message
...

The marks don't appear oily or damp. Are they possibly oil? Or could they
just be what they appear....marks? They are on all the blades, and kind
of
look like what friction might have caused. They seem to function
perfectly.


To clarify a bit, under the closest inspection I can manage, they appear
more like bright marks would look on a camera body. I see no actual
liquid.
Ken


More than likely wear marks. The black coating of the iris has worn from
being cycled so many times. Oil, on the other hand would look like a liquid
on the blades. The black would be deeper black, just as if you oiled or
Armor-All'ed the outside of the lens.

I've had two lens develop an 'oil leak' and had them professionally cleaned.
Not cheap...