A permanent record of the oscilloscope trace requires that the display be photographed. Oscilloscope cameras make this fairly easy to do. It has a hood that attaches to a mounting in front of the screen. The hood excludes ambient light and keeps the lens a fixed distance from the screen surface. The camera is permanently focused at this distance. The back of the camera holds standard polaroid film, providing instant copies of the trace. Oscilloscope cameras are available for almost any type of instrument. It is used for making permanent records of oscilloscopic observations.