Stereo photography

[ytf]

Such an interesting discussion: so interesting, in fact, that I have joined your forum in order to participate and perhaps answer some of your questions.
Thank you Xenedis for bringing my work to the attention of the forum.

As has been pointed out, the stereo photo is two separate photos taken several inches apart.(Yes, I'm American: I live in a world of inches, quarts, miles, etc.) I use a single Nikon D700 with older manual lenses. Since each photo needs to be as similar to it's mate as possible, auto-exposure and auto-focus can actually be a detriment. The benefit of a single camera is that the stereo base (distance between shots) can be easily varied depending on the subject matter. A general rule of thumb is a base 1/30th of the distance from the camera to the nearest foreground object. I don't actually measure, I just wing it. Some of the macro and pin-hole shots are only fractions of an inch apart. Others are as much as 40 or 50 feet. The result is a feeling of seeing the world as a Lilliputian in the former and as a Brobdingnagian in the latter. One also needs to take into account the focal length of the lens being used. I like a wide angle (my most used lens is a 20mm but I sometimes use a 200mm as well) which tends to require a wider base relative to distance than the longer lens. For instance, when shooting a cityscape from across the East River, my base is ideally about 35 feet. With the 200mm, however, I would shorten that to about 8 feet.

There are several cameras available which use 2 lenses and capture 2 images with a single snap. The greatest benefit to these cameras is that they can capture action. Me, I'm more of a still life kind of guy, so I have no real need for such a camera. A third option is a dual-camera rig. The most popular is made from a pair of Canon Point and Shoots using the CHDK hack to synchronize them. On could also use a pair of more advanced cameras, but the complexity rises exponentially when you consider that focal lengths of zoom lenses and focal planes need to match for each frame. The more complicated the rig, the more that can go wrong and fancy dual-camera rigs can get very pricey. I subscribe to the KISS principle (Keep It Simple, Stupid.) Since I shoot in a very crowded, fast moving environment, (New York City) I need to be able to shoot quickly and move on. Fiddling with gadgets is not an option.

There are a variety of viewing methods for stereo photography. The most traditional is parallel, in which the left-eye image is on the left and the right-eye image is on the right. I find this somewhat limiting in that most people (myself included) cannot freeview such an arrangement. A special viewer is needed and there is generally a limit to what sizes can be presented. An alternate and also rather traditional method is the red/cyan (anaglyph) method, long the staple of early "3D" movies. It is reasonably effective, but it tends to screw up the colours quite a bit. The third popular method is crossview. The left-eye image is placed on the right and the right-eye image on the left. The viewer crosses their eyes slightly until a single image with depth forms in the middle. This tends to be the most popular these days. It is rather simple to do, requires no special gadgets, larger sizes can be seen easily and the colours remain true. Note that no matter which viewing method is used, the photo can easily be changed to other styles. Most exhibitions are done using dual projection systems in which the images are mounted parallel.
Crossview is not nearly as difficult as it seems. Most people are quite capable of it and in fact do it constantly in their daily life without even realizing it. Try this: hold one finger up in front of your face. Without diverting your gaze from the finger, take not of things that are farther away. They will be double. Crossview is the same principle. With a bit of practice you can train your eyes to converge at a point closer to your face but focus on a point more distant. It is no more uncomfortable than if you were reading a book. If it feels uncomfortable, you're probably trying too hard.

One comment I read is that it seems like a gimmick. This is said about many things we accept in life. Painters have said that photography itself is a gimmick. Stereophotography is actually nearly as old as photography itself. In fact, Sir Charles Wheatstone presented the first treatise on binocular vision, describing the process of dual imagery, to the Royal Society in 1832. For those who know their photographic history, you will know that this was several years before the first photograph. The most widely accepted date for the first stereo photograph is about 1852. The first camera to use 35mm celluloid film was a stereo camera. In fact, stereophotography was widely used and accepted until the advent of Kodak's simple cameras made for use by the general public in the early decades of the last century. In order to reach the largest market, they kept it simple. (So much for KISS) Rather than partaking in a new gimmick, I consider myself upholding an old tradition. For the record, I'm not into 3D movies. I think I've only seen two in the last 30 years, and neither one was Avatar.

Feel free to browse my Flickr stream, www.flickr.com/photos/ytf. If you have any questions or comments, I would enjoy hearing them.

ytf