Re: IMAX 3-D L5

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Larry Berlin writes:

>In stereo, one tends to *travel* through the image much like one would scan
>the eyes through a real scene. If the image area that you scan to isn't
>focused, it's like wearing dirty glasses. You get the reflex to clean them.
>So shallow depth of field should be a problem for most persons in a stereo
>scene.

I challenge this statement.  (Oooooh (-; )  I think it depends on the
scene, and particularly, the subject.

I have taken some stereos of butterflies at the "Butterfly World" exhibit
at Marine World/Afrika.  In order to make the subject large enough to be
interesting, I was at the minimum focal distance for the camera, shooting
at about f5.6 using flash fill, and so the backgrounds tend to be
out-of-focus where visible.  In some of these shots, where the
foreground is busy enough (e.g. a curtain of palm leaves across the
entire shot), the fact that the background is out-of-focus doesn't
bother me at all, because the eye is never really drawn to it.  In one
shot where there are people and other distractions, the fact that it
is out-of-focus actually helps the image, just like selective focus
in a flat picture.

I do have another slide where the subject is a bird on a rope, and
the background is clearly visible and out-of-focus.  In this situation
it is very bothersome, because the eye quickly leaves the main subject
and wants to explore this background, since there's absolutely nothing
obscuring most of it and it makes up such a large part of the scene
compared with the main subject.

So I would conclude that selective focus DOES work in stereo, but the
situations where it works are much more limited than in 2D, and that
one should utilize it only when the foreground has a large amount of
interest to keep the eye "captive".

I'd like to hear others' opinions on this.  Do your observations agree
with mine?  Should make a nice controversy. :-)

        -Greg


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