Hyperstereo
"Hyperstereo" refers to a stereo image which uses a larger than normal stereo base (the distance between the left and right lenses). Recall that "normal" image separation is about 65 mm, so anything further apart than this is, by definition, hyperstereo.
Usually this is obtained by using two camera separated by a greater than normal distance, or by using a single camera, making two images separated by more than the normal distance. Depending on the subject, this distance can be tens or even humdreds of feet apart. This gives a stereo effect to objects which are far enough away that normally you would perceive no depth.
Here are some hints for playing with hyperstereo:
- As a guideline, use an image separation of about 1/30 to 1/50 of the distance to your main subject. For example, to photograph a mountain range 5 miles distant, you would want to try a camera separation in the range of 528 - 880 feet apart.
- You must exclude nearby objects from your photos. If you do not do so, you will create excessive on-film divergence in your images. If you don't believe this, just try it.
- Try to take both photos from the same level - avoid vertical changes between photos.
- You will need some method to get the same framing between photos. Use registration marks in the viewfinder, distant objects at the edges or center of the frame, etc., to adjust both images within the viewfinder.
- You may find it useful to switch to manual exposure to make sure both exposures are the same.
- Useful subjects are mountain ranges, city skylines (taken from opposite sides of a skyscraper), clouds, etc.
- If you are using a single camera, you may have to move very fast to avoid parts of the subject in motion. I suggest having someone drive your car, and take two photos at 65mph a few seconds apart. Even at this speed, clouds can move between photos, creating retinal rivalry.
- One useful place to take hyperstereo photos is on a commercial jet ride. You may wish to take 2, 3, or even 4 photos at various intervals. For example, take the first photo, wait 1 second, take another, wait 2 seconds, etc. (Better yet, use a camera with motorized advance to fire several frames in sequence.) This way you will get a wide variety of base separations to choose from.