“Professor Hank” recently wrote an Instructable on how to adapt your digital camera to create an anaglyph in a single exposure, with a single camera, and with no post-processing of the image needed, and for about a dollar in materials. An anaglyph is a photo that contains two separate images, in different colors, separated by a small amount. When viewed through viewing glasses that have different colored filters for each eye, the two images are combined by the brain into a 3 dimensional version of the original scene.
The thing I like about this Instructable is that it is very easy to construct and use, yet the “how it works” is quite technical. The Professor gives a very good explanation of how the technique works, and how to adapt it for your camera. You can read it for all the details, but basically you stop the camera aperture wide open, or as wide as you can without distortion. You make an aperture stop out of paper or cardboard that goes in front of the camera lens. This stop actually has two holes in it, one left of center and one right of center, as shown in the photo. This double aperture creates two distinct images on the image sensor, one focused through the left side of the lens and another focused through the right side.
To create the anaglyph you cut up a pair of paper 3D viewing glasses (green/magenta is best — the Instructable explains why) and place one of the colored gels over one aperture and the other colored gel over the other aperture. The gels divide the spectrum in half, so the two images in the anaglyph together contain all of the original spectrum information.
When the resulting image is viewed through another pair of 3D glasses with gels that match the ones used to take the picture, your brain reassembles the images into the original 3 dimensional scene. Simple as that!
The creation of the stop has some complicated technical details behind it. Fortunately the Professor has provided a WWW page into which you can enter the details about your camera such as focal length and desired f stop, and it will return an image that you can print out and cut up to make your aperture stop. There are also some considerations to know about when focusing and framing the image, which the Professor also discusses in the Instructable.
Note that the photo shows an aperture placed in front of the lens of a video camera. You can use this technique to create 3D movies also.
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