water damage

Just got a Minolta XE-5 off Ebay today. When I removed the lens, this is what I saw on the mirror. I'm new to collecting and shooting vintage cameras so this is new to me. Is this just water damage? Is this fungus? What's the worse case scenario? I want to try and clean it but I'm afraid I would...

Hi. This is my first post. I am very interested in photography and wish it were under different circumstances that I were posting. A month ago I had a water leak in my basement. Just yesterday I found that water had gotten into a box of photos 10 to 25 years old that had been developed from...