The camera obscura was believed to have been first discovered in China about three to four centuries BC. It consisted of a hole in a wall, which is known as a pin hole camera. It wasn't exactly invented but more of a discovery.
It is possible to actually make one in your own house. It needs a bit of experiment.
- If you have a small room with a window, get a piece of black card which is dense enough to stop light going through and is big enough to cover the window.
- Punch a hole in the middle about 3 to 5mm across. It should be a clean hole without any ragged edge.
- Get a sheet of white paper about A3 size and stand the paper upright opposite the hole. Now the distance needed is dependent on the size of the hole. This is where a bit of trial and error comes in.
- You will need to sit for some time in the dark until your eyes adjust and pick a bright sunny day. The sun should shine on the scene outside and not on the window.
- You can experiment with smaller and larger holes and vary the distance of the viewing paper.
- Once you have a sharp image, measure the distance from hole to viewing paper and divide the hole size into the distance. This will give you the focal length. If you make a larger hole, say one inch in diameter you can cover that with a removable piece with different size holes until it looks right.
- Finally you will have to stand on your head because the image will be upside down.