Photography - 3D

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It is surprisingly easy to create a 3D picture with any camera (digital or not) and view them either on screen or on paper. It does necessitate knowing a few things about the science of optics, however. Knowing some things about the process is vital to producing good results. Some mounting brackets and software packages can help here very much, but are not absolutely essential to produce decent results.

Principles

A 3D picture is made up of two images of the same scene taken from vantage points just a few inches apart. This is how the human eyes see things in three dimensions. Each of our two eyes sees the scene in front of us from slightly different angles. Those two images are combined in our brains, which are able to compare them and interperet the discrepancies between them as depth. This is known as binocular vision. Three-dimensional photography is simply taking two pictures from two locations a few inches apart from each other, and letting each eye see only one image. There are a number of ways to do this.

History Lesson

One of the earliest ways of letting each eye see a different image was a 19th Century device called a Stereoscope. The images were printed on a piece of paper about the size of a postcard, and placed in a holder attached to a pair of lenses. The aparatus was held up to the face for the scene to be viewed. Several modern stereoscopes are available for purchase today as well as reproductions of older models. The older picture cards are sold and traded among hobyists the same way that vintage baseball cards are. There is likely a 3D club near you that does this once in a while.

Another way to see 3D was made popular in the 1950's in the movie theaters. Two movie cameras were mounted together while filming the actors, and each movie was played back to audiances at the same time OVERLAPPING EACH OTHER ON THE SAME SCREEN. One projector was shining through a blue filter, and one was shown through a red filter. With the audiance members all wearing paper glasses with red and blue celophane lenses, only the red image gets through the red lens and on into the appropriate eye, and the blue image only gets through the blue lens to be seen by the designated blue eye. This only worked with black-and-white movies, of course, but since all movies were black-and-white at the time it was popular for a while. When this red/blue method is used, the photograph is refered to as an Anaglyph. Using special color techniques with different color lenses, today it is possible to just as easily produce full-color anaglyphs.

Anaglyph Example
Anaglyph Example

More recent motion picture innovations use polarized lenses on the projectors and glasses instead of the red/blue images. This allows full-color movies to be shown in the theaters. There have also been 3D movies that use a single projector where even numbered frames are intended for the left eye and the odd frames are intended for the right eye. To see these correctly, special glasses with LCD shutters are worn by the audiance. These shutters flash back and forth between transparent and opaque so that each eye only sees the frames it is supposed to see. This usually requires special equipment in the theater to make sure the electronic glasses are in perfect sync with the film.

No Equipment Necessary

Of course, it is also possible to view stereograms on the computer screen without any special equipment. You just have to train your eyes to look at pictures differently. I will admit that it takes some practice, (and might result in a headache the first time you try) but it can be done. There are two basic methods:

  1. Let your eyes drift apart by trying to look at something far off on the horizon. This will allow things up close to be seen as blurry double-images. Look at two pictures meant for the Left and Right eyes, and try to get the double-images to overlap. Once they do, you then have to get your eyes to focus on the nearby pictures, while remaining aligned for viewing something on the horizon. Some people find this easier to do than others. Please note that for this to work properly, the Left image needs to be on the Left side.
    3D Example - Left Eye
    Left Eye
    3D Example - Right Eye
    Right Eye

  2. Cross your eyes to form double-images. Line up these images until they overlap. Now focus your eyes on the images without uncrossing your eyes. This also takes some practice, but can be accomplished by more people than the first method. Notice here that for the crossed-eye method to work, the Left image needs to be on the Right side.
    3D Example - Right Eye
    Right Eye
    3D Example - Left Eye
    Left Eye

Equipment

The example pictures above were taken at the War Memorial in Memorial Park in my hometown. When I took these pictures, I held the camera in my hands (no tripod), leaned to the left to take a picture, then leaned to the right to take the other picture. Professionals use a tripod to make sure the pictures come out clear, and use a tripod attachment called a slider bar. This is a special mounting bracket you can buy for your tripod that lets the camera slide from the left position to the right position without changing the viewing angle. You can buy these for US$100 to US$300, or try to make your own out of scrap metal. (Yes, it's been done before.) As for myself, I just hold the camera steady, or move the tripod over a few inches. (Translation: I don't feel I do 3D often enough to justify that kind of price tag.) As you can see, even hand-held, the results can be quite good.

Separated at Birth?

Taking one picture, moving the camera, and taking another picture works fine if the subject is standing still. If there is any kind of movement in the scene, the slight time delay between taking two separate shots is unacceptable. (For instance, in the pictures above, notice how the flag moved from one picture to the next.) The way to overcome this limitation is to take both the left and right image at the same time. When film was still King, there were cameras made that had two shutters that both opened with the click of a single button. They were almost never sitting on a shelf in a retail store, so you probably had to ask someone to order one for you, but they could be located if you talked to a store owner who had the right supply catalogs. Some clever people even bought two identical cameras and jury-rigged a mounting bracket for them with a common trigger mechanism. This sort of thing could still work with digital cameras, but I wouldn't recommend it unless you know what you are doing. Today you have to do some searching to find a true digital 3D camera, but they are probably out there.

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Updated:
June 27, 2005