Pinhole Camera Ideally, this should be done in a darkened room. If this isn't possible, you may have to wrap your camera tightly in a tube of black sugar paper and look down the dark tube to see a clearer image. Make sure that you leave the foil end sticking out.
You will notice that the image is upside-down.
The diagram which accompanies these notes illustrates why.
The flame is emitting light in all directions but the only way in which light can get from the flame to the screen is to go through the pinhole.
Look at the diagram and notice the angle at which light from the top of the flame enters the hole.
It doesn't change direction but goes on to strike the bottom of the screen.
Similarly, light from the bottom of the flame ends up at the top of the screen.