A man’s wife dies of a terminal illness and he’s distraught that he couldn’t do anything to prevent it. He discovers that he can capture the moment a soul leaves its body with his camera, he then experiments and films people dying until he finds a way to trap a soul and thus achieve immortality (or bring his wife back). I don’t remember the ending, it’s horror genre. It’s an old film, English, saw it on TV in the 90s, might have been black and white.