The main disadvantage that the AFM has compared to the scanning electron microscope (SEM) is the image size. The SEM can show an area on the order of millimetres by millimetres and a depth of field on the order of millimetres. The AFM can only show a maximum height on the order of micrometres and a maximum area of around 100 by 100 micrometres. Additionally, the AFM cannot scan images as fast as an SEM. It may take several minutes for a typical region to be scanned with the AFM, however an SEM is capable of scanning at near real-time (although at relatively low quality).