There have been no substantial changes to copyright law in the last half-century; what has changed is how easily anyone who sees a creative work can now make their own copies and derivative works. In the past when professional photographers only used film, the negatives were required to make copies and it wasn't generally questioned that after you had purchased a number of prints, if you wanted more you had to go back to the photographer and buy more. Photographers have had to adapt to a new way of managing their intellectual rights as it no longer realistic to maintain total control over an image's reproduction, but the laws protecting them are the same as ever.