Re: In Search of Ortho-ness

[P3D Paul Talbot <ptww@xxxxxxxxx>]

>From the discussion of stereo portraits:

> >By ET effect do you mean really long outstretched arms, or large
> >nose and ears?  I think of the long arm and fingers problem as a
> >stretch problem; prominent nose and ears are normally associated
> >with a perspective problem (taking the picture too close to the
> >subject).
> 
> As far as portraits are concerned, I guess I'll have to be satisfied
> with staying my 7 feet away when I take my people pictures, until I
> get a camera that has longer lenses.

Note that longer FL lenses increase image size.  Perspective is a 
function of camera to subject distance.  Even with longer FL lenses,
it is recommended that portraits be taken with the camera six to
seven feet from the subject (if I remember the number correctly).

Does anyone know what FL lens is suitable for 5-Perf portraits from
the recommended distance?  It seems like it should be somewhat less
than the 80-105 FL recommended for normal 35mm format.

Also note that inside 7 feet parallax increases very fast!  If you
are closer than 7 feet and using normal stereo base, you will have to
severely restrict the depth in the scene.  Use the f/5.6 marks on
your DOF scale for an idea of how restricted the depth must be if
the subject is inside 7 feet.

Paul Talbot


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