2X2 Part 2

Why I Use 2x2 Part 2

by Dennis M. Hanser

In the first article in this series, I briefly explained the ‘cha cha’ method of taking a 3-d photograph. It was stated that you could make a 3-d picture by first taking an image while leaning slightly to the right on your right foot and, with the camera at your eye, releasing the shutter. Then, without removing the camera from your eye, shift slightly to the left and lean on your left foot, advance the film for the next exposure, release the shutter to make the left image. The shift should approximate normal eye separation (about 2 ½ inches). This method is relatively simple to learn and allows beginners, and also more experienced photographers, to make 3-d photographs without having to purchase special equipment.

While you can make perfectly acceptable 3-d photos in this way, there are a few things that can be done to improve the alignment of these photos. It is important that the camera be kept as level as possible. This can be accomplished by placing the camera on a level, stable surface, such as the edge of a picnic table, or the rail of a fence, the top of a car, etc. Then by moving the camera from the right position to the left while on this surface, a level camera can be maintained. You may want to use something between the camera and the surface to avoid scratching the camera or the surface you are sliding the camera on.

Another solution would be to use a small board to slide the camera on. The board could have a piece of wood trim glued or nailed along the back edge to help guide the camera and to maintain a parallel movement from the right to left position. This board could also be fitted with a tripod socket, T-nuts work well for this, and then the whole thing could be tripod mounted. Now remember that the camera is not really attached to anything, and you are merely using this device to help keep the camera aligned during the left and right sequential exposures, so don’t expect to leave the camera sitting loosely on the board. You will have to hang onto it at all times or risk having it leave the board in a manner that could be destructive. Better yet would be a device that would allow the camera to be firmly attached.

There IS such a device and it is called a slide bar. A slide bar is a camera platform that moves from side to side on a base. Some slide bars use a pair of rails to allow the platform to move on the base and others use a dovetailed channel. Movement is done in several ways. Some simply slide from side to side, some allow locking in place, some use geared movements, as in a focusing rail. In fact a focusing rail can be used as a slide bar simply by turning it side ways to allow movement from side to side instead of forward and back.

Slide bars can be built, purchased or borrowed. They can be made from something as simple as a drawer slide, or finely machined from the best of materials. You may be able to build your own slide bar using materials and methods you are familiar with. If you would rather purchase a slide bar, Bogen makes an affordable model for around $40. I currently own 5 slide bars of various types. Three are home made and two are commercially produced. Of these, the Bogen is the handiest and easiest to use. I would be glad to show these different designs to anyone who is interested.

A little now about using the slide bar. The camera is attached to the sliding platform and the base has a tripod mount that allows slide bar and camera to be attached to the tripod as a unit. NOW we have something that is reasonably sturdy and allows more precisely aligned stereo pairs to be made. By using the slide bar, the camera is kept in good horizontal alignment, and also will not tip up or down between exposures.

The slide bar also allows control over the base separation, the distance between the right and left positions. For most purposes, you will want to use a base separation that is equivalent to normal eye separation. But, with a slide bar, you are not limited to any fixed distance between the camera positions. This opens up a lot of new possibilities. By using different focal length lenses, and different base separations, you can make stereo photos that are not easily made with a standard stereo camera, but that is the subject for another article.

Future articles will also cover mounting 2x2, building and buying viewers for this format, and projection with standard 35mm projectors.