An automated camera assembly comprising a camera and a detector for triggering the camera, wherein the detector includes an adjustable field of view. The detector can include a sensor and a curtain for reducing a maximum field of view to an adjusted field of view. The curtain can include an opaque member movable relative to the sensor. The curtain can instead include a processor programmed to trigger the camera when the subject is within the adjusted field of view. The invention is also embodied in a method of adjusting a field of view of a detector. The method comprises detecting a first subject within a maximum field of view, triggering the camera after detecting the first subject within the maximum field of view, adjusting to an adjusted field of view, detecting a second subject within the adjusted field of view, and triggering the camera after detecting the second subject.