Re: Using the Nishika to make stereo pairs

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Douglas Cootey asks:

>On Sam's page there is a hacked Nishika.  Aren't the far right and far
>left lenses on my standard Nishika farther apart than the one's in Sam's
>camera?

Yes.  Sam's Nishika modification uses the first and third lens, giving
a stereo base of 36mm (each pair of lenses on this camera is separated
by 1/2 of a full 36mm frame, or ~18mm, so the Nishika affords the possible
stereobases of ~18mm, ~36mm and ~54mm).

>My far right and far left lenses are 56mm apart.  Does this mean that
>because my eyes are about 65mm apart that the images won't look quite
>right? Or is there more to it than that.

The parallax, and therefore the apparent depth in the scene, will be
diminished by the reduced stereobase, compared to a 65mm base.  This
effect is termed "hypostereo".  The opposite effect, where you use a
stereobase greater than 65mm, is called "hyperstereo", and causes the
apparent depth to be exaggerated.

A reduced stereobase is required when taking close-ups (as in macro
photography); ironically, the Nishika's lenses are not sharp at
distances less than about 3 feet (and some would say they are not
sharp at *any* distance).  However, an ordinary magnifying lens
can be used over pairs of lenses to afford a close-up capability.
This is discussed in Reel-3D's "Nimslo" book.

	-Greg W.


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