Kirsten Johnson’s mesmerizing Cameraperson is a collage of footage from 25 of the documentary films for which she’s been the person operating the camera over the past quarter-century, some of the best-known being Laura Poitras’s Citizenfour and Michael Moore’s Fahrenheit 9/11. Opening text describes the film as a memoir, and context for the mostly wordless clips tends to be limited to geographical location, though occasional captions provide more detail, such a montage of locales used by Serbian soldiers for the mass rapes during the ethnic cleansing of Bosnia, which cuts to the truck used in the horrific dragging death of James Byrd in 1998 Texas by white supremacists. As those examples suggest, many of the films are about the horrible, fucked-up things that people (mostly men) do to other people (mostly women and/or people of differing ethnicities), although Johnson manages to find signs of humanity throughout it all. But it’s not an unrelenting horror-show, and some of the most lovely moments are establishing shots and camera tests. In addition to being a primer on how the basic cinematic language of editing involves bringing together disparate images to create meaning and emotion, the challenging, deeply artistic Cameraperson is also exactly that kind of documentary that would be appropriate for a festival celebrating arthouse theaters.