I want to know how sports photo copyright works and if I can sell paintings that I make using photos from online. So for example, I painted Babe Ruth using a photo I found because I don't have any pictures of him. The painting resembles him but is in color would I still need permission from the photographer?

All Answers To Questions

No matter how many changes you made to the original, you still copied! Therefore you infringed copyright. Most photographers would feel flattered if someone used their images for a painting. So stay on the right side of the law and ask permission.

You are fine, those pictures are old and part of the public domain if you ask me. Also if you don't try mass producing anything it can still qualify as "Fan Art" which is totally fine.