How to Make a Camera Obscura

Camera obscura, which means “dark chamber”, is a more complete name for a camera—a device that allows light reflected off an object, to pass through a small hole in the thin wall of an enclosed chamber. The small hole focuses the light that passes into the chamber onto the back wall of the chamber, so that an image of the object can be seen on that surface. A camera obscura can be as large as a room, or it may be small, like the hand held cameras we use everyday. The image may be recorded either on film or digitally; or the image may simply be viewed and not recorded at all. The camera obscura described here does not take photographs, but allows you to view images to observe the optical principles of the camera obscura.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Empty 28-ounce tin can (like a large tomato can)
• Nail
• Hammer
• Scissors
• Large shoebox
• White tissue paper
• Duct Tape
• Thick rubber band that will stretch around the circumference of the tin can
• Large dark color towel or piece of heavy fabric

1. 

   Use the nail and hammer to punch a hole in the center of the closed end of your empty tin can. Remove the nail from the can after punching the hole.

2. 

   Place one layer of white tissue paper over the open end of your empty tin can. Stretch the rubber band around the can and tissue paper to secure the tissue paper so that it is taut over the end of the can. You have just constructed the basic camera obscura. The nail hole is the aperture through which light will pass. The tissue paper is the surface upon which the image will be projected. Because the tissue paper is translucent, you'll be able to see the image from the outside of your camera obscura once you place it in a dark viewing chamber.

3. 

   Cut a round opening, about an inch smaller than the diameter of your tin can, in one end of the shoe box. The shoebox will be the dark viewing chamber that will allow you to see images on the tissue paper back wall of your camera obscura.

4. 

   Cut a small viewing hole--about ¾ inch in diameter--in the opposite end of the shoebox. This is the hole through with you'll be able to view the back side (the tissue paper end) of your camera obscura.

5. 

   Use duct tape to secure the tin can camera obscura against the large circular hole in the shoebox. The small-nail-hole end should be facing out of the shoebox through the hole that you cut. Use duct tape to seal around the edges of the can, so that no extra light will get into the box. Be sure to leave the nail hole uncovered.

6. 
   The finished camera obscura. Here you can see the nail hole. The viewing hole is on the other end.

   Close the shoebox and use duct tape to cover any other holes or seams that might allow light into the shoebox viewing chamber. Be sure to leave the nail hole opening and the viewing hole uncovered. Your camera obscura and viewing chamber are complete!

7. 
   Find something, like this tree, to look at with your camera obscura.

   Take your camera obscura into a brightly lit area and find a subject to view.

8. 
   Notice that the image of the tree as seen through the camera obscura, is upside down. as if rotated.

   Hold the viewing hole of your camera obscura up to your eye. On the tissue paper surface you'll see your viewing subject. If you have trouble seeing the image in your camera obscura, cover your head and the viewing hole of your camera obscura with the towel or fabric, to block out light. When viewing your subject through your camera obscura, you'll notice that it is upside down and reversed left to right. This is because light rays reflect off an object at an angle, so that they pass through the aperture of the camera obscura and are projected on the tissue paper in transverse position.

Tips & Warnings

• Our modern day digital or film cameras are not the only easy to find examples of camera obscura--the human eye is also an excellent example of a camera obscura.
• You'll also notice that the image you see through your camera obscura is not crisp like a photograph. In film or digital cameras, a lens is used to focus the image more precisely, and mirrors are used to flip and reverse the image so that it is the same as you see with your eye.
• If you are wondering why your eye does not see images upside down and reversed like the camera obscura that you just made--well, it does. While your eye does have a lens for focusing, it does not have any mirrors to flip images around. It is your brain that has learned to interpret the image for you, so that you think you are seeing it right side up and correctly oriented, left to right.
• If you make the nail hole in your camera obscura larger, more light will enter the camera obscura; however, the image will be less focused. With a smaller nail hole, the image will be darker and more focused.
• Never use your camera obscura to look directly at the sun. Even though the nail hole in your camera obscura is small, looking directly at the sun can cause permanent damage to your eyes

Resources

• The Magic Mirror of Life: An appreciation of the camera obscura

[stephrenay]

on 8/6/2009 I always wanted to make one for myself. Thanks!