What you'll need:
- A sunny room, preferably with one window.
- A bright day.
- A roll of thick plastic refuse sacks.
- Masking tape.
What to do.
1) Cut open the sacks and stick them together into a sheet large enough to cover the window(s).
2) Tape the sheet of sacks up against the window.
3) Cut a 1cm hole in the middle of the sheet.
4) Sit back and let your eyes get used to the dark.
5) After a few minutes you should start seeing the outside world projected (upside down) all around your room. Cars will wizz along the walls and you'll see people in the street walking along your ceiling!
|View inside the room with the camera obscura set up. It you want to take a photo like this you'll have to use a long exposure (2-4 seconds should do the trick).|
|For comparison here's the same view out the window.|
What's going on?
Basically we've just made ourselves a great big pinhole camera! Light travels in a straight line and crosses over as it goes through the hole in the bags. The light carries on until it hits the wall in the room. So everything on your wall appears upside down.
There are loads of camera obscura's you can visit all over the world. My favourite is the observatory near the Clifton Suspension Bridge in Bristol. It has splendid views of the Bridge and the City.
1The term camera obscura comes from the latin for 'dark room'. So the word camera is actually just latin for 'room'!