Sonderkommando photographs
The photographer was a member of the Sonderkommando, a group of inmates forced to work in and around the gas chambers.  He took two photos from inside one of the gas chambers and two from outside.  To keep from being caught, he had to aim the camera from his hip and was not able to focus the camera.  The Polish resistance (a movement of Polish people fighting against the Nazis) snuck the camera film out of the camp in a toothpaste tube.