We saw in the previous posting that changing the stereo base changes the distance of the subject from the observer. The amount of movementis proportional to the change of the stereo base. For example, doubling the stereo base will pull the scene twice as close. Reducing the stereo base by half will push the screen twice back.
This leads to the concept of space control. By controlling the distance of an object to the camera and the stereo base, it is possible to alter and control the apparent dimensions and distance of this object.
Those who have mastered space control have produced fascinating illusions by multiple exposures, like the ones shown by Tommy Thomas in the book “The Stereo Realist Manual”. Examples include the miniature girl inside the wine glass or the artist who is painting a picture of a live model (see left).
Here is how this illusion is produced: Start by taking a picture of the artist with the canvas covered by the dark cloth. Then proceed to double-expose the model in the area inside the dark cloth. To achieve this, the model must be photographed from a distance (to reduce the size) with increased stereo base (to be pulled closer). This requires very good planning and lots of patience and luck!
Digital photography can certainly make these kinds of effects easier to produce in the “digital darkroom”, but what do I know? :)