The present invention provides an automated camera assembly comprising a camera (e.g., a digital camera) having a field of vision and a detector for detecting a subject and triggering the camera. The detector has an adjustable field of view and includes a sensor (e.g., an IR sensor) having a maximum field of view, and a curtain for reducing the maximum field of view to an adjusted field of view. The curtain comprises at least two sections (e.g., opaque members) coupled to move together from a first position corresponding with the maximum field of view to a second position corresponding with the adjusted field of view smaller than the maximum field of view. Movement of the curtain relative to the sensor can be linear, pivotal, radial, or any other suitable movement.