Quote Originally Posted by bobwysiwyg View Post
This is pretty straight forward. The only thing I might add is the light doesn't 'spread' so much as the light point will appear 'opposite' positionally within the camera. At least that's my explanation.

http://www.howstuffworks.com/question131.htm
Originally known as Camera Obscura. A room, or tent, with a pinhole aperture that projects an image on the backwall or an easel for tracing by an artist or draftsman inside a darkened room. The diameter of the pin hole is related to the focal length, or distance between the pinhole and the capturing surface; the wall, a piece of film, photo paper, whatever. If the diameter of the aperture is too large, like a window, there will not be the inversion and focusing of the image. I think that theoretically, there is an optimum focal length for each pinhloe aperture that will focus perfectly, or am I wrong about that? So, in theory, if the focal length was long enough wouldn't an aperture as large as a window focus an image?