P3D Re: Divergent infinity

[aifxtony@xxxxxxxxxxxxx (Tony Alderson)]

I noticed something interesting at our first competition of the season.
Many of the slides, especially the 2x2x2 pairs, had excessive parallax.  At
least one slide (very nice photographically...) had far points over a foot
apart on the screen.  Now, by  the common standards, this should have been
"unviewable."  It was not, however.

I did feel some eyestrain from the divergence, but it was not intolerable.
I should note that I was at the back of the audience, and I did not
interview people who sat up front as to their threshold of pain.  However,
more than once I was requested BY THE JUDGES to readjust the horizontals in
such a way that increased the far point separation.

(Let's not get into another war about projector adjustment.  Not for a few
more months, anyway...  ;-)   My philosophy is "harm reduction," rather
like giving clean needles to heroin addicts....)

Anyway, the really interesting thing is that slides with an infinity
separation of a foot didn't seem any deeper than slides with two and a half
inches.  So is infinity infinity, and further separation buys nothing but
increasing eyestrain?  It would be interesting to compare an "excessive"
slide side-by-side with a "standard" slide, to see if this is really true.
(it's hard to tell in sequential projection)

At any rate, it seems (as others have noted) that the relationship between
parallax and perceived depth is not linear.  Has anyone else looked into
this?

Tony



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