T3D Example of impossible situation

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

I plugged a few numbers at Joel's stereo base calculator:

Near object: 100 mm
Far object:  105 mm

FL of lens used: 50 mm.

This is the situation of a macro taken at 1:1 (M = 1) with a
50 mm lens and a scene that has 5 mm depth in it (from near
to far object).  Note that at 1:1 a 50 mm lens is extended
100 off the film.

Answer for base which gives 1.2 mm on film deviation: 50.4 mm.

Try this in real life and see what happens. :-)  You will not
get a stereo pair.

Again, I think spreadsheets and curves for macro stereo
photography should be modidifed to take the amount of
overlap into account.  Do not display as solutions situations
that have negative overlap!  Put a flag if the overlap falls
below 67%.

George Themelis


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