Kirsten Johnson’s Cameraperson begins with a voice on the sound track—a disembodied whisper of delight and discovery—as an image of wildflowers pops up, their heads bobbing in close-up beside a farmhouse’s barbed-wire fence. (The location, a title card informs you, is Bosnia.) A flock of sheep comes trotting up, driven along the hilly road by a shepherd on a white horse, and Johnson, still unseen behind her camera, impulsively runs after him, laughing and panting. Then, almost without transition, you see the panorama of a rural highway in Missouri. The road is deserted and silent, the horizon low, the clouds a vast twilight wash of purple and indigo. Suddenly, a distant bolt of lightning splits the left side of the frame, top to bottom, and from behind the camera comes…