Straying from the hotheaded “Taxi Driver” style that has dominated much of his career, Paul Schrader pays ruminative and respectful tribute to his late friend, novelist Russell Banks, who gave the writer-director the raw material for one of his best films, “Affliction” — and now, for one of his best films in years. Adapted from Banks’ “Foregone” (and given the title the author told Schrader he wanted for the book), “Oh, Canada” presents a dying artist’s final testimony as a multifaceted film-within-a-film, honoring Banks while also revealing so many of Schrader’s own thoughts on mortality.

Fighting a long, painful bout with cancer, documentary filmmaker Leonard Fife has scores of admirers and a shelf full of awards. As the movie opens, two former students, Malcolm (Michael Imperioli) and Diana (Victoria Hill), arrive at their mentor’s Montreal home and proceed to set up a unique camera rig. It’s a...