When photography was introduced in 1839, exposure times took several minutes. To obtain a reasonably clear image, the camera could not be handheld and the photographer looked through the back of the camera under a black cloth before loading a sensitive plate, while his subjects had to stay totally still. Special head-rests and arm-rests could be used, and even if a subject managed to stay comfortable under these circumstances, they had to try to keep their facial expression in check if they wanted their features to properly show on the picture.