As you saw in the previous section, when you focus a Fuji 3D camera you also place the stereo window at the same point on which you focus. When you then fuse the stereo pair—be it on the camera, a stereo card, a TV, computer monitor, or a cinema screen—the 3D image appears to fall on a transparent plane at the surface of the physical image. This transparent plane is what's referred to as the stereo window and although it's placed when you take a picture you can move it forward and back in the scene using a photo-editing program such as StereoPhoto Maker as discussed in the Adjusting a Stereo Window section in Chapter 4. Its placement has a dramatic impact on how depth is presented and how easily a viewer can fuse the stereo pair.

To see the effect of moving the stereo window you superimpose the two images in a stereo pair so you can see through the top one to the bottom one. By then horizontally moving the images relative to each other you can superimpose identical points found in both images—technically called homologous points. The stereo window always falls on the points you superimpose.

Effects of Placing the Stereo Window

If you fuse the stereo pair as you move the stereo window, you'll see that the window appears to remain in a fixed position while the scene moves back and forth through it. Depending on where you place it, here is what you can expect to see:

• When you place the stereo window on the closest part of the scene, or even a little in front of it, all of the scene appears to lie behind the window—called positive parallax and the left eye view is to the left of the right eye view. This makes it more like you are looking at the subject through a window but the 3D effects are not very dramatic. Most people find this the best placement for fusing images with minimal effort and discomfort.
• When you place the stereo window on the most distant part of the scene all of the scene appears to lie in front of the window—called negative parallax. This gives a more dramatic 3D effect, but is a strain to view. In fact there are people who believe stereo movies died in the 1950s because this "poke-in- the-eye" effect was overdone. As early as the 1930s Edwin Land was quoted as saying when alluding to the coming-outthru the screen effects that later characterized the 3D films of the early 50s, " …to intrude too obviously on the real world of the auditorium can detract from our ability to enjoy vicariously the world of the motion picture as it unfolds on the screen. Those who voice a general objection to the heightened realism of stereo may well be protesting against the violation of this proper boundary. Our great goal should be to make movies as real as life around us, but this reality must be confined to the "other side" of the proscenium (stereo window). The greater the technological perfection of this other world, the more wholely we can identify ourselves with it— while safely outside."

  When using this effect it's best if those parts of the scene in front of the window don't touch the frame or they will have an amputated appearance. It will appear as if an object in front of the stereo window is cut off by the window behind it. This doesn't happen in the real world, so it appears confusing and is referred to as a window violation. One way to eliminate the violation is to add a floating border to the image as described in the section Adding a Floating Window in Chapter 4.

• When you place the stereo window on the middle ground, objects closer to the camera appear to lie in front of the window and more distant objects appear behind it— called zero parallax. This is a bit of a compromise between the other two alignments and works well when you want just part of the scene to protrude into your space. Again, any element in the scene that you want to protrude shouldn't touch the edges of the frame.

  Which alignment you use depends on the subject matter and what you want to show. For example, a portrait may work best when slightly behind the window so the near points pop out from the screen. For a landscape, you may put the front most object at or slightly behind the window so you appear to be looking at the scene through a window.

Seeing the Stereo Window on a Fuji 3D Camera

On Fuji Real 3D cameras you can use the parallax control to manually move the stereo window forward and back while in playback mode and see the effect on the monitor. The amount of change is displayed in the lowerright corner of the monitor. Just as when you adjust the stereo window in a photo-editing program, the images shift horizontally. As they do so, the monitor only displays the central portion containing parts of the scene common to both images and this area shrinks as you move the stereo window farther back in the scene.