Photographers often submit photos to publishers for inclusion in a book
or magazine. But what happens to the copyright for that photo? Does it
transfer to the publisher? What is the publisher allowed to do with the
copyright?

Unless the copyright to a photo is specifically transferred in total to a
publisher, the publisher’s use of that photo is limited by the usage
agreement. The publisher, however, creates a new copyright, called a
“collective work,” when your photo is combined with other photos, text,
illustrations, etc. Your photo then is covered by two copyrights – one for
the photo itself, and the other as part of a collective work.