Physical ownership vs copyright

the text below is copied from the online art forum ARTSY 7/12 2017

The tumult surrounding Maier’s estate boils down to this issue:
​the distinction between physical ownership of a photograph and copyright ownership. Under U.S. law, copyright encompasses the author’s right to its first sale or rental, reproduction, creation of derivative works (such as prints), and public exhibition of the work. Such rights can only be transferred in writing. During her lifetime, Maier held the copyright to her work (which is always the case unless an artist assigns or sells those rights to another).

While Maier had relinquished her property rights to the objects left in the storage unit, she still held the copyrights in the absence of a written document explicitly stating otherwise—and such copyrights endure for 70 years after an artist’s death. Accordingly, because Maloof and Goldstein owned the physical negatives or photographs and not the copyright, their ability to exploit the work commercially without the copyright owner’s permission is limited to selling only that physical copy that they had, themselves, purchased.