[frank]

I just bought a used Nikkor AF-D 28-105mm f3.5-4.5 from a local shop. After carefully checking the lens again after I bought it, I found some brownish material sticked on the rear part of the lens (please see the attached image: inside the two red squares). I thought it could be some "oil leak". I searched the net about oil leak and found that the case of my lens does not look like the often talked "oil leak problem". I touched the outer browndish material with a teeth stick, it is not like liquid.



Can anybody tell me what it is? I hope that it is not some kind of dried oil (otherwise new leaked oil will get into the camera).



Thank you in advance,

Frank