Re: Converging fields of view

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

Neil Harrington writes:

>"Offset" may imply a lateral shifting of the
>point of view while still looking straight ahead, as though that were the
>reason for the left lens seeing more of the right side of the subject, and
>this isn't true.

I think I see where we're coming at this differently.  From my point of
view, I think of the lenses as looking straight head, strictly.  Offsetting
the apertures from the center of the lens then results in a masking of
the scene.  The *EFFECT* of that masking, if you project the lines back
from the film plane through the center of the lens, is in fact converging
fields of view.  Do you see what I'm getting at?  The fields of view of
the *lenses* are not convergent, they're parallel, but the fields of view of
the *recorded images* are convergent.  This describes the whole system.

>If you imagine
>the central line of view for each frame to be a plain hollow tube from the
>center of that frame passing through the center of the corresponding lens,
>those two hollow tubes would converge, the lines of sight crossing at the
>window

I agree with this statement.  It is accurate as far as it goes, but it
doesn't describe the complete system (i.e. parallel lens axes and
co-planar film planes).

	-Greg


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