Juggling in Three Dimensions at the St Louis Festival

 by Duane Starcher

 

Ed. note: Starcher took along a stereo camera to the lJA's St. Louis Festival and was eager to share the fruits of his work with others through the magazine. We invited him to do so, and to explain the technique of taking and viewing the images.

 

A stereo pair of images is viewed by looking at the left image with the !eft eye and the right image with the right eye. Unless you have an optical viewer or an old stereoscope, you must learn to "free view." Some find this easier than others, but nearly everyone with two good eyes can manage it with a bit of practice.

 

Free viewing involves relaxing the eyes as if you were looking at an object on the horizon. Stare off into the distance, then raise the photograph into your line of sight about a foot in front of your eyes. Keep star­ing into the distance as if you were looking through the picture. If it is out of focus at first, don't worry. Once you get the images to lock, you will be able to adjust focus and look around the scene without losing the stereo effect.

 

When you succeed, you see one stereo image in the center with two outside "ghost" images that you ignore. The center combination of the left and right images will trigger your brain to interpret it as a scene with depth. The simpler the image, the easier the brain can sort it all out, so start with the drawing of the circles. You should see one circle with a vertical bar floating above it.

 

The camera I used in St. Louis is a Pentax K1000 with a 50mm lens. Attached to it is a beam splitter that screws on like a lens shade, also made by Pentax. It consists of two sets of two mirrors, gathering two images 2-3/4" apart, the normal separation of the eyes. This creates a pair of side-by-side vertical format 3-D images on each 35mm negative.

 

Regular 3-1/2" x 5" (or 4"x6") prints are obtained from the processor and can either be free-viewed as they are or trimmed and mounted to eliminate a stripe of blurred information in the middle.

 

When the trimmed prints are mounted on 4''x7'' cards, they can be inserted in the old stereopticon viewers that were popular from the 19th Century up until the Depression of the 1930's. Today, cheap plastic viewers can be purchased which magnify the images 2-3 times and make the scenes much easier to view.

 

Clearer images can be obtained by using two cameras, but problems of shutter and flash synchronization have to be overcome. But it's a technique I intend to try, so if all goes well, you may see a strange pair of lenses pointed at you at the Montreal festival next summer! *

 

 

For more information, contact Starcher at St. John's, Newfoundland, Canada