A Brief History and Methodology of Stereoscopic Photography
photography was invented practically at the same time with conventional
photography in 1839. The stereoscope was invented by
Sir Charles Wheatstone in England, who also coined its name and
introduced it in 1838. It used mirrors to reflect the two pictures to
the eyes. Initially it was used to look at carefully constructed
drawings and soon after photography was invented the first stereoscopic
photographs were also created. The Scotsman Sir David Brewster
introduced the first lens stereoscope in 1849 and since then many and
varied stereoscopes have been constructed and used. The most famous of
these stereoscopes was perfected by the American, Oliver Wendell Holmes
around 1859. The latter can be still found in antique shops around the
is Stereoscopic Photography?
Stereoscopic photography is achieved by
photographing an image from two slightly different viewpoints at the
same time, creating two pictures that look almost identical. When
viewing the paired images, the left picture is presented to the left eye
and the right picture to the right eye. The brain reconstructs the
pictures into a combined single image, which is perceived as a real
three-dimensional image. This image has all the cues of a flat
photograph, plus the depth that flat photographs do not have. Due to the
depth of the image, observers of the image feel as if they are at the
actual scene where the photograph was taken.
Stereoscopic cameras have two lenses
that take two pictures at once. The photographer can use standard print
or slide film for these pictures. It is possible to use a conventional
single lens camera to take very successful stereoscopic pictures as long
as the subject doesn’t move. The photographer achieves this by taking
one picture and shifting the camera slightly to one side to take another
picture, resulting in a stereoscopic pair.
Are Stereo Images Viewed?
stereoscopic image is composed of two images, left and right, we must
have a method of presenting only one image to one eye, and the other to
the other eye. There are many methods that are used to achieve this.
Stereoscopes enable us to view stereo prints
or slides. Stereoscopes present one view to one eye and the other view
the other eye. It is even possible for people to train their eyes to see
a stereoscopic image without the aid of any device. One can also project
a pair of transparencies on a screen with special projectors and view
these with polarizing glasses. The glasses allow each eye to see only
one image, left image with the left eye and right with the right eye.
Another method which is used in making lenticular photographs employs many narrow
vertical lenses molded on a single sheet of plastic, placed on top of many
vertical narrow left and
right images. Those lenses restrict the angle of view in such a way that each eye
sees only the image intended for that eye and from that specific angle.
is New in 3D Photography?
Electronic shutter glasses can be used
to see stereoscopic images. With such glasses, two slightly different
images are presented separately to each eye for a very brief period of
time, but because of the persistence of vision, we are fooled to believe
that we are looking at a real image from two slightly different angles.
These images can be created artificially on a computer, photographed
using 3D still cameras, or using 3D motion picture cameras. The
electronic goggles present one image to one eye for a fraction of a
second, then present the other image briefly to the other eye. This
process is repeated many times per second. From these alternating images
and because of the principle of persistence of vision, we get the
feeling of looking at a real 3D scene in front of us.
Free-Viewing Stereoscopic Images
It is possible to train your eyes to
fuse two stereo images without the aid of a stereoscope. Two methods are
in use: Parallel Free-Viewing and Cross Eyed Free-Viewing. Some people
feel easier using one method and some feel more comfortable with the
other. To facilitate all people, we arrange a triplet consisting of the
left image, followed by the right image and finally again the left
Look at the triplet of images below and
initially concentrate on the left and center image. We will try first to
train your eyes to fuse these two images in parallel viewing so that
your left eye will see only the left picture, and the right eye only the
right picture. Let your eyes relax and don’t focus them on the surface
of the pictures. Let your eyes gaze into infinity and pretend that you
are looking “through” the pictures. Keep staring without focusing
your eyes and soon you will see three blurry images. Concentrate on the
center image until all of a sudden it will pop clearly in 3D. Now you
are using the parallel free viewing method.
Next, we will train your eyes to
free-view by crossing them. Concentrate on the center and far right
images. Cross your eyes slightly and focus them about half way to the
images. Hold the tip of your finger in front of you to help you focus
half way. Don’t focus on the images but keep focusing half way by
looking at the tip of your finger with the two images behind it and out
of focus. Soon you will see three blurred images. Keep staring at the
same point until a clear image pops up in 3D.
Congratulations, you are now able to fuse the images by crossing or by parallel viewing the images.
East Side Esplanade, Portland, OR USA
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