Frida (1986)
If you manage to find this somewhere (I got my DVD on ebay) you'll see why the actress playing Frida is something of a small legend for her role. Ofelia Medina as the adult Kahlo is quite astonishing, highly believable, and often so Kahlo-like you have to remind yourself this isn't a documentary. She acting.
In fact, the whole movie is convincing in its realism even though it is not especially a "good" movie in other ways. What it lacks mostly is some kind of narrative drive. I don't mean you have to make up a fictional story line, certainly not with someone as amazing as Frida Kahlo, but there has to be something to keep the propulsion going. At the end she dies, and at the beginning she is young and being assessed with a childhood disease, but between it is a series of important things that happened to the artist.
So what you have is a collection of particular moments that really work--the accident aftermath is gruesome and terrifying, the final arrival in her bed at the exhibition is exhilarating--mixed with atmospheric filler, including lots of scenes of people playing music.
One surprising element all along is all the singing, including by Kahlo and even by Rivera. At one point they even have a comic operatic duet as they sing back and forth, quite hilarious and perhaps in keeping with two people filled with life. At times you might think the movie is a musical, but overall it's a low-budget, sincere, genuine feeling biopic. It's that genuine-ness that makes it worth the trip to ebay. Mexico comes across as the real deal, colorful and peppered with what seem like amateur actors, and filmed not in fancied up rooms and courtyards but simple, honest locations.
One of the revelations of this "Frida" is how the more famous 2002 "Frida" looks overly perfect, truly "Hollywood" in its slick, beautiful, colorful rendering of the same subject. Some of the scenes are so similar you realize that this earlier Mexican "Frida" was the template for the later American one (the Trotsky scenes in particular). Certainly the American one is better made and is easier to watch, and will move you. This Mexican one is more a corrective, a realization about who Frida really might have been, and about the falseness of even very good movies.