P3D Re: PHOTO-3D digest 2965

[abram klooswyk <abram.klooswyk@xxxxxx>]

I wrote:
> (...) remove a center strip from the mount(...)
> bringing the viewing stereowindow closer.
> This means in fact for the 5P system not a 1/30 base but a 1/15 base.

RM  (Bob_Maxey) wrote: 
>If one is modifying the separation in the mount, to
>me, this is NOT a modification of the Stereo Base.

You are right, I'm sorry for a too hasty and therefore incorrect
formulation. I meant: 
If you use double depth mounting (as indicated) you can use a depth
range in the photography, which equals not a 1/30 base but a 1/15 base. 

>By the above reasoning, I can shoot (to some extent) slide-bar
>stereo without regard to any specific stereo base, and fix / correct 
>it in the mounting.

This is true to a little extent :-) 
As stereo is about viewing, all reasoning depends on the way of viewing.
Mostly all these discussions suppose viewing stereoprojection, in which 
depth range is most critical. Then in fact audience size is also a 
factor, with large audiences probably more people are far from the 
"orthostereo seat". Then double depth views probably should be 
exceptions.

In stereoscope viewing much more is possible. General van Albada in the
1930's demonstrated (and published) stereo's of nature scenes with depth 
ranges from 40 cm (16 inches) to infinity, using a 65 mm base. 
This is 1/6 !  Even in the stereoscope this is not often viewable. 
[Don't try this at home :-) ]
Only scenes with objects at all distances, and no great depth gaps 
between them, can sometimes be viewable with such stereo bases. 
Relying on correction in mounting is indeed not the way to do it.

Abram (bonehead) Klooswyk


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