And there's a vast and varied photography world beyond sports too. Art photography, modern, historical, etc etc. The good thing is if you have a basic knowledge of old baseball photos you have a similar knowledge of similar non-sport photos-- Presidents, movies, etc. Movie photos are similar to sports press photos, and a cabinet card of Abe Lincoln will be similar to a baseball player cabinet card.
Modern photography is very interesting too.
St. Peterburg cabinet card of the Romanov Family by the official Royal photographer. Notice the text is Russian.
Union Generals Custor and Pleasanton in 1863
Lucky Luciano and his dog relaxing at the piano in Italy. Standard news photo from after he was deported.
1850s tintype of young man and his dog in original case
Original large 1990s negative for Chanel fashion catalog by Karl Lagerfeld. Digitally switched to positive image for viewing purposes.
The Romanov and Civil War Generals photos sold for around the $9,000-$12,000 each, as they are both exceptional and rare examples of historical photos. The Luciano news photo would be cheap. The Chanel negative would probably go for $100-$200 due to the famous photographer and model (Helena Christensen), that fashion photography is popular and it's a stylish image. That's my hand holding the dog tintype, but I don't know what it sold for or if it sold. I examined it for an auction house, but it never showed up in the catalog. Maybe the owner decided to keep it. Tintypes of animals are not common, but you see them around. As you can imagine, animals are always popular subjects with collectors.
Oh, and the Custer photo was professionally restored. It was deacified and the not shown backing is modern acid free paper. It's an original of a famous image that appears in a Custer biography.