P3D 1:30 rule, breaking it big-time!

[boris@xxxxxxxxxxxx (Boris Starosta)]

I thought I would enter an opinion on this matter of the 1:30 rule.  I am
about five digests behind in my reading, so this may be a little late.
Also, I have been forced to skim a lot of this thread - my apologies if I
am simply repeating someone else's statements.

In the past I have said that I think the 1:30 rule was very detrimental to
stereo, because it cajoles most people into taking pictures with relatively
little depth - in particular, it tends to discourage people from closeups.
Related to that is the fact that most stereo cameras are designed for
subject matter beyond six feet of range.

Either that, or the rule encourages the use of insufficient stereobase.  I
saw an entry into a folio recently - a beautiful picture of a vase and
flowers, black cloth background, about three feet from the camera - it was
a wonderful subject with great complexity, spatial detail, etc.  But I was
disappointed to see that the shot unnecessarily hurt by the application of
the rule.  The photographer was unaware of the fact that in his particular
shot, on film deviation was not going to be a problem, even if the ratio
had been 1:10!  He should have used a normal interaxial!  Instead the shot
ended up looking flat and not realistic.

Here I am just repeating what others have already pointed out - that the
1:30 rule, if applied without regard to the space being photographed, will
sometimes produce on film deviations much less than the "acceptable"
maximum of 1.2(?)mm - or in other words, the rule serves simply to keep you
within the acceptable limits, no matter what the depth of the scene.

But if you seek more depth in a view, as I often do, the spatial
composition can mitigate even very large on film deviations.  I think as
long as you have a continuous progression in depth, large disparities can
be digested by most people.

http://www.starosta.com/3dshowcase/ihex.html

My image of the Pixie is an example of this.  On a 35mm slide, the OFD is
over 4mm between the grasses in the foreground and the most distant hills!
Yet the slide has been accepted into every PSA intl. exhibition into which
it has been submitted, and it has also won a few awards.

How can such a large OFD escape the notice of the selectors (whose stereo
sensibilities I am always challenging)?  Two reasons, I think: 1. the plane
of water, grasses, and lilies provides a smooth continuous transition to
extreme depth (or in other words, "local" disparities are never too large),
and 2. the distant objects are very pale (distance haze), so that the
disparities do not intrude as much.

Respectfully submitted,

Here's a nice quotation my wife just found for me:
"Eroticism is using a feather; pornography is using the whole hen."
- Isabel Allende - Aphrodite

Boris Starosta            boris@xxxxxxxxxxxx
                          http://www.starosta.com
usa 804 979 3930          http://www.starosta.com/3dshowcase



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End of PHOTO-3D Digest 2939
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