Few years back I bought old manual telephoto lens, or so called 'Wonder Tube'
They ave available in places like ebay for about 50$ depending on condition. The one I bought was Tele-Universar 400mm f/6.3.
Sadly upon arrival it was found out that back optics are in quite bad condition, it was quite hazy, I did manage to find original fungus picture (before it was cleaned)
It looked like this monstrosity...
As can be seen there are both fungus, haze so as some condensation, probably oil from aperture blades, might be wrong. I have also heard that some people used to apply cream on old lenses to get hazed effect, so as such lenses were relatively cheap and produced by many manufactures.
I did not use it much in this condition but I took few test shots, the one in start of post is one of them.
I must admit I kind of like that natural haze effect... it also made outcome seem like monochrome or graystyle.
Say what you think :)