Photographs capture places and events, but they lack the impression of depth. Ever since Charles Wheatstone discovered the principles of stereo vision in 1838, people have been trying to take stereo photographs. Stereoscopic or 3-D images use two shots of the same scene taken from slightly different viewpoints. By looking at them in a certain way or by using stereo viewers the images are combined in our mind to produce a 3-D effect, which arises from the fact that each of our eyes has a slightly different view on the world. By taking two pictures 2.5” apart (the average distance between right and left eye of most people) we get a 3-D shot.
Problem with stereo cameras is that they are based on old technology. There isn't a cheap modern day alternative, though it is possible to use a digicam by creating a guide rail, which keeps the lens perfectly parallel and lets you slide the camera 2.5” between shots. Select a scene where nothing is moving and include a foreground subject for a stereo effect. Keep distance, exposure and focal length exactly the same between shots.
To view images in 3-D without a stereoscope, arrange them side by side and stare at a point between them. Slowly cross your eyes and the images should merge so a 3-D image appears in the middle. When practising this, take a break if your eyes get tired and remember that not everyone can do this technique.