First of all: how many cameras are needed to shoot stereoscopic photos?

In the section    Creating a 3D image  we have already given part of the answer: just one if you are satisfied of shooting still objects, which do not move between shots.

You can, for instance, adopt the cha-cha method explained in that section which is very simple but requires a little practice at the beginning and a skill mostly in maintaining the axes of the lenses parallel between shots.

Or you can use a slide-bar, a sliding bar to which the camera gets fixed: as you can see from the image on the right, you make the first shot, shift the camera and then make the second shot.

It is surely a good starting point and you can buy it from their site:   Photo3D  ; when you'll become more sophisticated, you'll be able to find other sites where to choose between several models and prices and better quality.

Or, you'll enjoy to make it on your own.

The compromise to have just one camera and the possibility to shoot objects moving is the adoption of a beamsplitter, that is a device that, usually, takes the place of your lenses and, through a system of mirrors or similar, let you shoot a stereo pair. The resulting photo will show the left and rigth images side-by-side; however, this means to give up to half of the width resolution ! The leader in the field seems to be Loreo (   Loreo) who delivers several models depending on the used camera. Anyway, the fact that this beamsplitter replaces your lenses makes this device unsuitable for a professionale use.

If you desire to express your creativity at the best level you need a real 3D camera. Several (non digital) models were produced in the '50s which can be still found on the stalls of second-hand photo markets.

It is, on the other hand, difficult to find 3D digital cameras, but you can try to ask to Sebastian Allmendinger (   RBT). The option is to twin horizontally or vertically two exactly alike cameras. If you are going to try this, just remember that the most critical points are the synch of the focal lenght and of the focus (which have to be absolutely the same).