Introduction

Introduction to Stereo Photography

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We humans are fortunate to perceive the world with binocular vision. The overlapping field of view provided by the eyes allows a sense of how far away objects are from oneself, and oneself from everything else.

Many factors contribute to our sense of depth perception, but one is particularly important: As you survey the world around you, your eyes present to your brain not a simple double image, but two views from horizontally offset points of view. These two planar images projected onto the retinae are fused in the brain into one image. The disparity - the distance between corresponding points in each image - provides the cue your mind needs to place you and everything else in three dimensional space.

Although many other techniques exist, the classic means to capture a stereo image is with film. Using a single camera with a normal focal length lens (to mimic human visual perspective), the stereographer can take two images approximately 2.5 inches apart (the average human interpupilary distance) and, with careful presentation of the images to the eyes (a stereoscope or viewing apperatus), recreate the same spatial scene the viewer would see as if she were standing at the original location.

Inventors have created many ingenious devices to capture and present 3D media. Among the most popular is the Victorian Age stereogram print and stereoscope viewer. The stereo photography fad of the 1940s and '50s produced a wide variety of slide film cameras, illuminated hand-held viewers, and projectors. This equipment is not only widely available on the used market, but is relatively inexpensive and offers a refreshingly mechanical interface.

With 3D modeling and image editing software now affordable on personal computers, completely constructed worlds offer an endless playground for virtual stereo cameras. Take a stereo pair of the love of your life with your film camera, scan the images to PhotoCD, whip up a moonscape in Bryce2, collage the scenes in Photoshop, output to film, and your babe's outta this world in 3D.

The ideal of capturing a stereo image faithful to reality (as humans perceive it, that is) involves many considerations and compromises to successfully create the illusion of depth. The photographer draws upon a simultaneous awareness of many technical and aesthetic principles to find the right balance of compromises to capture the image as intended.

Stereo photography (and computer-generated stereo imagery) adds a layer of complexity and many restrictions to the art. A reasonable question to ask is, "and for what?" Does the addition of depth perception return enough reward for the effort? Technically incorrect and aesthetically uninspired images certainly not.

But made with skill and passion, a stereo slide glows like a pair of backlit jewels, offering a private peek into not only a moment in time, but an entire space filled with color, shapes, and depth. Once you've done it in stereo, everything else seems, well…, flat.

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