Re: In search of simple 3D formulas

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

Gregg Lobdell writes:
 
> Novice 3D photographer in search of simple rules of thumb 
> for solo SLR rail 3DJphotography.
 
There's one very simple rule and that is, keep your maximum 
on-film deviation down to about 1/30th of the focal length of 
your system.  Then your results will be viewable by all.  This 
works out to about 1.2 mm for miniature format and 2.7 mm for 
medium format stereo cameras.  If you're using a 50 mm SLR and 
50 mm (Star D) viewer, then obviously you're allowed a little 
more.  To measure on-film deviation, take your two film chips 
and lay one on top of the other.  Superimpose the two most 
distant objects in the scene and then measure the separation of 
the two nearest objects in the scene.  I would go into the math 
of how to calculate on-film deviation but it's been done so many 
times on this list that folks will think very badly of me if I 
do it again.  Besides, it will be fun for you to figure out the 
geometry (if you don't prefer to cheat and look in the archives 
for how to do it 8-).
 
John B
 
Friend WJC asks where I've been.  My design group is overloaded and 
u-no-hoo is picking up the excess because same can not legally ask his
people to put in more hours gratis nor does same have the $$$ to hire 
more.  It's a very temporary situation of course, only been going 
on for about a year now.  The good news is that the situation is 
changing and the bad news is that it's for the worse.  I've just now 
read the past three days' worth of digests.  Lots of interesting 
questions and answers in this group.  I wish I could have joined in.


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