I got this Pentax M42 50 1.4 in today and, although it is in great shape, it has a bunch of tiny black spots in the lens. I've attached a picture and they show up blurred, but to the eye they look just like tiny black dots (kinda like small metal flakes or something similar). I've gotten a couple of these legacy lens and don't know a lot about them. This one came off Ebay. Can somebody tell me if this is dust, fungus or something else? Thank you in advance for your help and sorry the picture isn't better.