This site has some good information- it's for a Minolta camera, but lenses are lenses when it comes to fungus and oil: http://reviews.ebay.com/How-To-Detect-Flaws-in-Used-Camera-Lenses-on-Ebay_W0QQugidZ10000000001005542 It's also a good article. Basically, it takes keen inspection. And they also use ultra-violet light. Here's another good site: http://www.zeisscamera.com/services_overhaul-cIIa-lenses.shtml Here's some examples of fungus (except for the "exaggerated" one): http://www.pentaxforums.com/forums/pentax-beginners-corner-q/78911-what-does-lens-fungus-look-like.html If you don't see anything with a 20x loupe and good lighting, I wouldn't think you have anything to worry about. Good luck, and hope this helps.
Answers & Comments
This site has some good information- it's for a Minolta camera, but lenses are lenses when it comes to fungus and oil:
http://reviews.ebay.com/How-To-Detect-Flaws-in-Used-Camera-Lenses-on-Ebay_W0QQugidZ10000000001005542
It's also a good article.
Basically, it takes keen inspection. And they also use ultra-violet light. Here's another good site:
http://www.zeisscamera.com/services_overhaul-cIIa-lenses.shtml
Here's some examples of fungus (except for the "exaggerated" one):
http://www.pentaxforums.com/forums/pentax-beginners-corner-q/78911-what-does-lens-fungus-look-like.html
If you don't see anything with a 20x loupe and good lighting, I wouldn't think you have anything to worry about.
Good luck, and hope this helps.