P3D Re: The "rule" is not a rule at all.

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

>There are no right or wrong numbers.  And you certainly don't need 
>a programmable calculator to do stereo photography.  

Let me clarify this... Tom insists that the 1/30 is black magic
and he directs us to his web site to get the "right numbers".
IMO, blindly following any rule is wrong.  You must understand
1) what the problem is, 2) what the rule does for you.

The 1/30 rule is derived assuming that the furthest object is at
infinity.  If it is not at infinity, then there are other "rules".
For example, using the f8 marks in a Realist DOF scale will give
you the depth range to aim for.  

All these rules aim in restricting the maximum deviation in a stereo
image so it can be viewed comfortably.  They were not given by God
and the world is not going to end if you violate them.  There are
photographic situations that "demand" more or less than Tom's
"golden spreadsheet" predicts. For example, portraits, definitely
less.  Strong hyperstereos, more.  Issues like subject matter and
personal preferences are coming into the picture.

My advice is to understand the physical principles involved here,
derive some of these formulas for yourself, experiment & develop
an intuition which, at the end, will be more valuable than any 
calculator.

George Themelis
DrT-3d@xxxxxxx