The statement Robert Mapplethorpe made with his photographs was practically self-evident. Every one of his pictures says “I think this is beautiful.” But the statement is followed by a question: “Don’t you?” Seen more than one at a time, his images create provocative, often startling juxtapositions. Consider the spadix of a white calla lily emerging from the center of the flower, next to, say, a man’s penis hanging outside the unzipped pants of a suit. Mapplethorpe’s question became one of the most controversial in modern art. And one that continued to linger long after his death in 1989, at age 42, from AIDS.

“Mapplethorpe,” directed by Ondi Timoner, is a fictionalized biography of the photographer that is most alive when it’s putting its subject’s pictures on the screen, which it does often. And should have done more, because the movie is otherwise as timid as its subject was bold. Beginning with young Mapplethorpe in uniform as an R.O.T.C. cadet at Pratt, it cuts to some “New York City! Wow!” archival footage before the rebellious Robert meets cute with the poet Patti. The alliance between Mapplethorpe and the future rock star Patti Smith was movingly memorialized and mythologized by Smith herself in the 2010 book “Just Kids.” It came as both a surprise, and maybe not so much of one, to be informed in its pages that Smith was the practical one in the relationship. For all that, the art-worshipping duo were fierce nonconformists.

“Mapplethorpe” does something I thought impossible: It makes Smith and Mapplethorpe kind of boring. The scene in which they dance together to a Tim Hardin record could be dropped into the middle of an episode of “This Is Us” and you’d never know the difference. (Patti is played, with a blandness that’s near-hilarious, by Marianne Rendón.)