Diaz, now sixty-seven years old, is a venerated figure at international film festivals, his work justly acclaimed for its observational acuity and novelistic texture. His approach is often described in terms of what he doesn’t do: he is skeptical of narrative convention, allergic to closeups, and loath to move the camera within a scene—unless, as in “Magellan,” it happens to be on a raft, floating downstream under a gentle tropical shower, or on a ship, bobbing along on Atlantic waves. (The director shot and edited the film himself, with Artur Tort.) He also shies away from direct depictions of slaughter, preferring to cut to the aftermath, with gruesome matter-of-factness. “Magellan” isn’t an action movie; it’s a consequence movie. But Diaz, within all this meticulous subtraction, adds dramatic heft and political meaning. In draining any visceral excitement from violence, he subtly decolonizes the camera’s gaze. “Magellan,” a tale of death, disease, mutiny, and mutually assured destruction, is the most powerful anti-imperialist epic I’ve seen since Lucrecia Martel’s “Zama” (2018), which fixed a withering comic glare on the expansionist bloodlust of eighteenth-century Europe. Diaz’s instincts aren’t as viciously funny, though a bone-dry comedy does rear its head when one character loses his: during the voyage, a shipmaster, caught having sex with a cabin boy belowdecks, is put to death for “crimes against nature.”