The vast majority of photographers take for granted that what they see in the viewfinder of their camera is what they will see in the resulting exposed image.
When you have made a pinhole camera though you have to determine the angle of view. This can be extreme especially when your camera is thin or deep.
My suitcase camera has a focal length of 99mm. I knew that this would produce a wide angle of view but I decided it was best to test the parameters of my new toy before I took it out on some serious fieldwork.
Exposure time - 13 minutes
Distance of camera from skull - 100cm
Exposure time - 3 hours
Distance of camera from skull - 5cm