A black body assembly is provided for use in the calibration of infrared cameras. The assembly includes, among other things, a housing within which calibration components may be situated, and a lens guide for accurately positioning the assembly over a lens of the infrared camera. A heat emitter may be positioned within the housing for emitting a necessary amount of heat for calibration purposes. A heating element may also be provided within the housing for controlling the heating and cooling of the heat emitter. The assembly may also include a heat sink to remove excessive heat generated from the thermoelectric cooler during temperature cycling. An arm may be employed to hingedly connect the assembly to the camera to provide reliable and repeatable way to position the black body assembly at the front of the infrared lens. A method for calibrating an infrared camera is also provided.