stereophotography

Stereophotography (also known as 3D photography), is a technique for taking pictures that can afterwards be viewed in a manner that creates a "stereo" image - an image that appears to have 3 dimensions.

In 1833, Charles Wheatstone made the first images that caused "stereopsis", or the perception of depth. It is interesting to note that such images can be drawn without any special instruments or equipment, and were thus possible long before. He exhibited these drawings with a mirror stereoscope. In 1841, he put this knowledge to use by creating a camera that could take photographs that properly exhibited this effect.

Most commonly, a stereo camera is used to take stereo pictures, as it will expose film from the two slightly different angles at the same time, creating a pair of images that will almost always create the desired effect.

A conventional camera can be used to copy this effect, provided the proper method of viewing, and precision is used when taking the pictures. Essentially, to do so, take a picture of a subject, then move the camera about 7 cm to the side, and photograph the same subject again. This will, in theory, give pictures that can be viewed as a stereogram.

Photographs taken in this manner require a special viewer, a stereoscope. This device causes each eye to view a slightly different image, and the differences in viewing angle are identical to that normally experienced, and thus the picture is seen as having three dimensions.

There was a short time where stereophotography received a lot of attention. Around the end of the 19th century and the early 20th century, there was quite a bit of interest and popularity for stereophotography. It was often used in little entertainment machines that would show images in stereo, and there was even a special mirror device made by Theodore Brown that allowed normal cameras to take stereo photographs.

But today, stereophotography is not often used or viewed by the average person. But it does get a bit of use in the sciences, such as remote survey and medical imaging, as quite a bit more information can be gleaned from a stereogram than from a regular simple photograph, as information on depth is nearly non-existent in such pictures.

_{Sources:
Stereoscopy: Where Did It Come From? Where Will It Lead?, http://userwww.sfsu.edu/~hl/stereo.html
Stereophotography, http://www.homestead.com/stereophotography/
Blink-O-Scopes: Binocular Cinematography and 3-D Magic, http://www.3dgear.com/scsc/December%20Issue/page3.html}

Now that digital photography is commonplace, it is trivial to take stereo pictures of static objects, and no stereoscope is needed to view them!

Simply set your camera to lock in the exposure of the scene you want to take a stereograph of, then take one picture, move the camera about 10cm to the right, reframe the subject, and take a second picture. Make sure focus and exposure remain the same between the two photos.

Always take either the left or the right photo first, so you don't have to keep track of which is which. Then, on the computer, resize the photos so they both fit on the screen, then paste them both into a new document. Place the "left side" photo on the right, and the "right side" photo on the left. The two copies of the object of interest shouldn't be too far apart; a few inches at most.

Now, sit back and cross your eyes so that the two images overlap... You should suddenly see your scene in 3D! This requires no special equipment; only the ability to cross your eyes.

A few downsides, of course:

• The scene must be static; it is probably difficult to take a stereographic photo of your cat this way.
• Your camera must support exposure and focus lock; if not, the results may come out strange, and of course
• Crossing your eyes can become uncomfortable after a while, and you or someone you are showing the photos to may not be able to do this. (my mother can't, for instance)

Note that you can exaggerate the 3D effect in some scenes by taking the photos further apart, and reduce the effect (helpful at close range) by taking them closer together.

Enjoy your newfound 3D photo taking ability!