Re: Camera shift spacing

[P3D john bercovitz <bercov@xxxxxxxxxxx>]

Vince Macek writes:
> I read in David Burder & Pat Whitehouse's book 'Photographing in 3D" about
> the 1:30 ratio; that is, the camera shift, or interocular, would be 1/30th
> the distance from camera to subject.
 
I'd be really careful with this one.  This rule comes from making assumptions
which allow simplification of the 1/30 of focal length rule.  Unfortunately,
the assumptions preclude using the rule for macros.  Better stick with the
uncondensed rule for that situation.  All the uncondensed rule says is that
the maximum allowable deviation on the film should not exceed 1/30 of the focal
length of the lens.  How do you measure on-film deviation?  Easy, lay one film
chip on top of the other and superimpose the most distant points in the scene.
Now measure the distance between the closest points in the scene.  You're done.
If you want to calculate it ahead of time and geometry isn't your forte, use
the MAOFD program at bobcat's ftp site.
 
John B


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