Am I right about stereo limits and enchanement?

clear glass wrote:

The stereo effect depends upon the difference in the distance of near and far objects in the image.

It is also affected by the distance between the two lenses in the camera or binocular.

(I seem to recall a standard distance between lenses to mimic the eyes, but aren't stereo images sometimes made by two lenses with a different separation in a pair of binoculars, a picture from space, or one camera shifted to make a stereo pair of a stationary object I also seem to recall that stereo closeups need lenses with non-standard separation, and this is accomplished sometimes by close-up lenses with prisms.

Do I have any idea what I'm talking about?

Has anyone heard of eyeglasses with prisms that optically increase or decrease stereo sepatation know what the effect it has on the stereo view?

An increase in interaxial separation results in the effect called "Hyperstereo". It is useful for showing enhanced depths of scene elements at greater distances. Very close elements must be avoided, as they would have excess deviation (result: uncomfortable or impossible viewing). Binoculars typically have a wider separation than the eyes, so they will more easily show a better depth between distant objects. Some binoculars for military use can have VERY wide separation (several feet).

A decrease in interaxial separation results in the effect called "Hypostereo", where it decreases the depths shown for distant scene elements, but permits closer elements to be included and to show depth in those elements, without causing excess deviation. Typically, Hypostereo can be of use in Macro photography, while keeping distant elements within reasonable deviation. Stereo Microscopes have closer interaxials, for instance. So do some compact binoculars, designed that way to be, well, compact! A few surgical glasses also have decreased interaxial optics, to show depths for the very fine and close handwork, while keeping deviations comfortable. It's akin to "wearing a stereo microscope". Most surgical glasses are simply loupes that "toe in" heavily, though, which effectively produces a closer interaxial. And the wearer compensates for the resulting keystone distortion (I hope!).

There are several mirror-type stereo viewers that will increase the interaxial. Most of these have no magnification lenses.

The pokescope viewer uses lens wedges, and so does the classic Holmes card viewer to increase the "effective" separation slightly. There are eyeglass-integrated prism-type viewers that work too. Many of these optics include magnification, so they would not work for viewing distant scenes by eye.