Re: [photo-3d] R: . Re: Camera separation in stereo photography

["don lopp" <dlopp@xxxxxxxxxxxxxxx>]

----- Original Message -----
From: "Sergio Baldissara" <winter@xxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Wednesday, June 28, 2000 5:00 PM
Subject: [photo-3d] R: . Re: Camera separation in stereo photography


> Ciao!
> While reading this thread (when does the 1/30th rule apply?) I realized
most
> people speak about focal lenght but seem to forget the film frame format.
> It should be useless to remind the 1/30th formula approximates the more
> accurate formula:
> Base = (distance from Near point) x (max allowed Deviation of homologous
> points [on film]) / (Focal lenght), say b=n*d/f.
> "d allowed deviation" is usually said to be1,2 mm (36mm/30) on 135 film
> (24x36mm frame), and 3mm (9cm/30) on 120 film (6x9cm frame), in other
words
> roughly 2 degree parallax.
> In our experience we realize those figures were set very cautiously, as
> 1,2mm usually also works for Realist format, and 3mm for 6x6 format. In
both
> cases horizontal deviation substends a parallax of about  3 degrees.
> Can we dare more? It's a difficult question to answer.
> Fusion capacity physiologically varies between individuals: some skilled
> stereo watchers are even able to freeview stereocards in parallel format.
> But... (as usual I'm heretic) we mustn't confy on the observers' ability
to
> fuse (some 3d photographers sometimes do so, and even seem to challenge
the
> skill of their audience).
> Indeed the only thing that really matters is the ability of our stereos to
> capture other people's  eyes and drive their brains to stereo vision.
> When we display pics to other stereoscopists, we deal with people willing
to
> fuse, skilled in fusion, even not caring about some little eyestrain.
> But if we want to show our work to laymen, we must be more cautious: we
need
> to capture the automatic fusion of 100% of our audience... unless we want
to
> keep stereoscopy as an exoteric art...
> ciao dall'Italia!
> Sergio
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