Originally posted by GerryL Another thing, fungus grows.
Even if it might be dead, it can still have spores that can, with the right conditions, grow into another fungus again.
If you attach that to your camera, and attach other lenses (that have no fungus) to that camera, the fungus can transfer and you might have a fungus garden in all your lenses AND camera!
From what I've been reading, as long as there's not a breach in the end of the lens which attaches to the body of the camera; & the fungus is only on the front glass, then it's not likely the fungus will jump into the inside of your camera.
However, to be on the safe side, I would do a quick clean of the outside of the back lens, put it on, shoot away and then remove it.
There are a number of posts on suggestions of where to store & how to kill fungus.
The 50mm 1.7 is pretty simple to clean. You'll need to do a little reading, & put together a small cleaning kit.
I realized that if I'm going to be using older lenses I was going to have to learn at least the basics of how to clean, dismantle, and store them.