The amount of stereo effect is defined, in part, by the separation of the camera lenses, which defines the relative parallax differential between the left and right eye images.

If the inter ocular distance (the distance between the camera lenses – more accurately the interaxial separation) is too large objects in the close foreground, or in the far background, can be excessively separated by the exaggerated stereo effect, causing the human eye/brain combination to have to work harder than expected to bring the image into focus - which breaks the suspension of disbelief that theatres rely on to immerse the audience within the story, and can easily invoke headaches due to the unrealistic nature of the image.

This first image is repeated from a previous page, and has an inter ocular distance of approximately 2 inches.

While this following image has an inter ocular distance of 4 inches, and the difference is obvious.

With the exaggerated stereo effect comes a lengthening of the apparent distances between objects, as well as the length of the objects themselves, obvious by comparing the above two images.

This can cause some very unnatural looking images, especially where the human body is concerned, with overly long, and very thin looking arms, not to mention the effect of miniaturisation...

From the camera perspective, stereoscopic 3-D requires two cameras, as shown on the previous pages with the Viper rig, and as shown below.

However, the problem with the Viper rig shown on previous pages, and the Sony rig above, is that the inter ocular distance (the distance between the two lenses) is too great for any relative close-up shots, as the stereo effect will be too exaggerated, causing the issues outlined above and within the miniaturisation page.

The following rig uses two smaller Iconix cameras on a rig that can get to just about the optimal 2.5 inch inter ocular distance...

And in the following image a mirror rig is used which allows for the setting of small interocular values down to zero - and yes, that is me in the background...

Next Page - miniaturisation

As always, test before committing to a particular style of stereoscopic 3-D shooting.

Or better still, contact steve@lightillusion.com for more info.