Hi,
I bought a 50 mm Summicron secondhand a couple of years ago. Judging from the serial number, I think it was produced around 2001 or so.
Anyway, I have noticed dark marks on some the aperture blades. Judging from the images below, can anyone tell if this is oil or something else? And whether or not it might affect image quality (and thus should be sent for repair)?
I'm not worried about the resell value as I intend to keep it. But I would like it to be in good condition as it is my most used lens on the Leica.
Thanks in advance.