Re: [photo-3d] Base Calculation?

[Mike Kersenbrock <michaelk@xxxxxxxxxxxx>]

dougorama@xxxxxxx wrote:
> 
> At a given subject distance, a wider angle lens demands a wider base.
> True or false?

Certainly false.  "Demands" is a pretty strong word, likely to be
disputed no matter what is said around it.  :-)

In any case, I'd suspect the opposite to be true in a 
preference contest.  Short lenses probably will result (with common
viewers) to exaggerate depth where a narrower base would tend to
"compensate" (as well as the camera being moved *closer* when the 
photographer tries to compensate for the smaller images in the
wider angle lens).

Whereas perspective is based on where the camera is, not the
lens that's on it, that moving closer can be a problem (igoring
for now that there also would be more near subject in the wide-angle case
which is what I find to be a real problem if not watched for).

> Base for 20mm lenses should be ~60mm with a subject at about 1m.
> True or false?

When I used  16mm lenses on my stereo camera (75mm spacing) something
that seemed to be 1m away in the viewfinder REALLY would have been
at 8 inches, and that does nasty things to the end-viewer's eyes.

It's the "real" distance, not the apparent distance that has to be
"watched".   Or at least judging from my first roll of 16mm lens
stereo photography.  Conclusions subject to change with further 
experimentation. :-)

Mike K.

P.S. - I'm using the (ebay) inexpensive Russian lenses, and so far
       they're quite nice, but "interesting" to use.  :-)