I know I have a Photomic finder. I don't know much about them though since I don't own a Nikon F. It was in the bag with my FM when I bought it. I know it has fungus in it though. Not sure how easy it'd be to clear it. I haven't tried. But I can check when I get home if you're interested. I'm not even sure if it works or not. I don't have an F, so I've never had use for it.