What is a camera obscura?
While it might have “camera” in its name, a camera obscura is actually more like a projector. It is a device used by using a dark room or box and adding a small hole in one wall which will let light in. The light that travels through the aperture (the small hole) will create a projection on the other walls. This was an ancient technique used by artists and scientists for centuries. Artists loved it because it would allow them to study perspective and tracing landscapes and easily matching colors. Scientists loved it because they could use it to observe astrological events like solar eclipses without staring directly at the sun, and the device itself is a fascinating demonstration of how light travels.
How can I make a camera obscura in my room?
Watch this video of Juliette turning her own room into a camera obscura, and then get the instructions so you can do it yourself!
- A room (preferably one with a blank wall across from a window)
- Cardboard (Enough to cover all of the windows in the room)
- Painter’s tape
- Ruler or toilet paper roll tube
- A piece of cardstock
Step One: Cut a small square out of the center of the cardboard at least 2×2 inches.
Step Two: Cover the windows with your cardboard, use painter’s tape to hold the cardboard in place and cover any cracks of light.
Step Three: Using your ruler measure a and draw a circle with a diameter of 1.5 inches on the center of your cardstock. You could also trace the inside of a toilet paper roll.
Step Four: Cut the circle you drew out of the cardstock.
Step Five: Tape the cut piece of cardstock to the 2×2” opening of the cardboard. (make sure the circle isn’t being covered.)
Step Six: Close the door and block out any extra light that might be entering the room.
Now all you have to do is wait in the room for about 10 minutes, to allow your eyes to adjust to the dark, and you should be able to see the projection on the wall opposite the aperture!
What’s the science: Why is the projection upside down?
Light travels in a straight line, unless its path is blocked or altered by something like a mirror or water. But because there is a hole allowing light in, all of the light is essentially funneled through the aperture, the paths of light cross over each other, and create a flipped projection of light. This is the same way light travels through our own eyes, the only reason we see things as right side up is because our brains know to flip the image so we aren’t stumbling around all the time!
As time went on the addition of mirrors was made so the image could be observed right side up. As well as scientists experimented with the size of the aperture and lenses so that the projection could let in more light and be focused.
What happens if you change the size of your aperture? Try a different size hole and observe the results.
Do you notice any changes if you use different materials to cover your window?
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