Okay, kids, Nat Finkelstein has written me asking me to ask you to request permission from him if you're going to post his photos. His email address is firstname.lastname@example.org. Regardless of anyone's personal view on this, it IS his legal right to control his copyrighted photos. If he were to write LJ Abuse asking them to close this community for copyright infrigement (which he did not threaten to do in his email to me), they would, because they don't want to be sued themselves. So please try to comply with this to avoid community deletion.
I realize that when you save photos from somewhere, the photographer was not credited, and so you don't know who it is. That's a tricky thing to navigate, but I'd say to go ahead and post, and I'll ask Mr. Finkelstein to comment about it if it's one of his photographs.