Converging fields of view

[P3D Neil Harrington <nharrington@xxxxxxxxxxxxx>]

Greg Wageman writes:

>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.  

Well, the lens axes are lined up straight ahead, yes.  Of course "looking"
implies "seeing," and there isn't any "seeing" except where there's film.
Since the film apertures are offset, I wouldn't say that the "seeing" is
being done straight ahead, considering the fields of view in their entirety.

>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.  

So far, so good.    :-)

>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.

Well . . . I do think we're spiraling in on a very tiny semantics point
here.  I've always taken "fields of view" to imply "as 'seen' by the film,"
since otherwise the term doesn't really have much meaning for me.  I think
in all previous discussions of this I've been careful to speak of the "left
frame" or the "left-lens side," etc., to make a distinction between
properties of the lens alone and the lens/film system, the latter being the
important thing.



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