Cinema and Subjectivity A camera obscura and a camera are only essentially different in their size and the presence or absence of film. So let's go back to that quirky eclipsed tree, for the principle that explains all three phenomena.
Light travels in straight lines.
Now the rays are obstructed for the most part by the opague surface of the camera obscura, but the lucky ray that passes through to hole still has the information of the last object it was reflected of off. And it reassembles that information on the first smooth surface it hits. There's a Web site in the Webliography that makes a large but undertheorized case for this anyway. After reading their version of Vermeer and the camera obscura, be sure to read Jonathan Crary's assessment of the art historical stakes in this connection.