There are a lot of questions and answers around this subject on G2G.
However, I did want to call everyone's attention to this disclaimer on Ancestry.com
Remember that information you post within the Ancestry Community may become public to other users (depending on your privacy settings). This means that other users can copy and use the information you provide. If another user updates a person in their tree based on what you have shared in your tree, the information will include a source indicating that the information is from your tree. If they add a photo or story from your tree, it will show you as the original contributor. Although you may receive credit for your contributions, you don’t have total control over what others may do with the content you share.
Thanks, Lucy. Something being made public does not mean that it is public domain, just that it is visible publicly.
Photos taken after 1978 would still be under copyright of the photographer and use would descend to his/her heirs and not the owner of one of the prints.