[MF3D.FORUM:1001] Deviation, the stereo window, and the projection window

[Richard Twichell <rmt@xxxxxxxxxxxxxxx>]

Deviation is determined at the moment the shutter clicks, and cannot be
changed by any mounting technique except cropping.  The stereo window is
determined by the distance between the centers of the slide mount.  Any
pair of homologues which is less than this distance apart has come
through the window, violating it if it touches an edge.

In projection, converging the chips on the screen to reduce excessive
parallax does not effect the stereo window, but moves the projection
window, which is the point in space where the two projected frames
coincide. Whether or not this is a good thing to do is a point of some
debate among projectionists.  Among the factors to consider in deciding
about this are:  size of screen, distance to the first row, stereo
viewing experience of the audience, and ambient light in the house.  And
the most important factors:  amount of parallax in the slides to be
projected, and quality of the mounting.

As we will be presenting MF projection at NSA Buffalo, I look forward to
a good, thorough discussion of these issues, particularly among those of
us who will be presenting MF shows.

Dick Twichell