How To Free View Stereoscopic Pairs
written for the stereosite by Steven Nossiter, USA
There are two types of stereoscopic pairs, parallel view and cross view. Parallel displays the images with the right and left images aligned with the right and left eye. Cross view swaps right for left and requires that you cross your eyes to see the 3D effect. All traditional stereo cards are parallel view, and I enjoy being able to pick up a card and just free view it.
When you first look at a stereo image pair, your left eye and your right eye each see the entire card, and your mind assembles that into one view of the entire card; a normal view.
When you allow your eyes to each focus on their ‘own’ side of the pair then each eye still sees the pair of images as they diverge, thus causing double vision.
This appears as three (or four) frames until you succeed in mentally merging the central, 3D image, and ignoring the outer frames.
Unfortunately, this information is not especially helpful when learning to free view because the technique is not so much intellectual as it is physiological and psychological. But the following practice guide might be helpful. Though, don’t expect to be successful at the first time. You might be. Otherwise, take time…
I have to say that any written explanation of how to free view is difficult, because the technique varies a bit from person to person, and it is simply difficult to explain in words. Last but not least, free viewing has some advantages, but is not necessary if you have a viewer.
Sit in a comfortable chair that allows a stable position relative to the screen. Set up the stereo image about 5.5 to 6 inches wide (14 to 15 cm), level with the eyes, and at least arm’s length away to start (something like 24 to 28 inches; approx. 66cm). Some people may like to be farther away; the centers of the images should appear the same distance apart as your eyes.
Close (or block) your right eye; gaze at the left image with your left eye. Then switch: close (or block) your left eye; gaze at the right image with your right eye. Repeat, slowly several times. When each eye settles easily on its image then with one eye open, smoothly open the other eye without trying to focus — just gaze. Relax, and don’t attempt to concentrate, just allow the eyes to do what they do. You will see three images. Without changing the focus or direction of either eye, focus your mind on the central image. It will give the impression of depth to a greater or lesser degree. With practice you will be able to mentally block out the individual images and only see the 3D central image.
The first couple of times you may find your eyes changing back to normal focus, to see the pair as a pair. If you dont see what I’m describing after trying several times, try to relax and gaze over the top of the screen, maybe imagining you are looking across a room or out a window, just daydreaming. Without changing focus allow your gaze to move down to the stereo image pair, and you will see three images. Relax, let go of all expectations and the images will converge until you see the central image become 3D.
For Cross View, use the same sequence as in the first method, only with right eye to left image, and vice versa. With a little practice you will experience a whole new dimension of photography!
These rather simple graphic images are chosen to allow easy parallel free viewing:
If you are able to free view these stereo pairs try the following photo.
Steven Nossiter (Cape Cod, Massachusetts, USA)
I am a graduate of the New England School of Photography’s two-year Professional Photography Program (1995). I’ve done freelance news photography, promotional portraits for performers and many years of teaching photography to individuals and community education classes. My work has been shown in numerous informal settings, and juried into regional and national exhibitions.
I have explored a variety of non-traditional and experimental photography, specializing in digital false color infrared. Since I acquired a Stereo Realist camera in 2012 I’ve had a strong interest in stereo photography.