Re: 1 to 30 rule

[P3D Paul Talbot <ptww@xxxxxxxxx>]

Re: gecko wants to know how to use the 1-to-30 rule for a hyper-stereo
of a cityscape.  As Charles Piper states over and over in "The
Technical Page," you should use a 1-to-50 rule if you intend to
project the slides.  The 1-to-30 rule should be considered a maximum
stereo base, and if used at all should be limited to slides that will
only be viewed in a hand-viewer.  Unfortunately, I don't have any good
tips for how to determine what the distance is it it is beyond the
measured distance range of your focus scale.

Some tips have appeared on the list in the fairly recent past about
using the deviation in the viewfinder as your guide to when you have
moved the cameras far enough apart.  Someone who has done this could
do a better job than I could of explaining it clearly, or you might be
able to track it down in the archives.  Browse on over to:
http://bobcat.etsu.edu/ftpdir/photo/photo-3d/digests/ghindex.html

It is probably also a good idea to bracket your stereo base, and
select the best result.  Piper recommends a maximum on-film deviation
of .7mm for projected Realist format slides.

Paul Talbot


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