[filmscanners] RE: Depth of Focus (was Nikon LS-40 vs Polaroid SS4000)

["Austin Franklin" <darkroom@ix.netcom.com>]

> The problem is depth of field by the way.

Here, I'll help you out dickbo.  Depth of focus is the correct term to use
when discussing film scanner film flatness.

As quoted from "Modern Optical Engineering" by Warren Smith, page 156:

"The photographic depth of focus

The photographic depth of focus is based on the concept that a defocused
blur which is smaller than a silver grain in the film emulsion will not be
noticeable.  This concept also can be applied to a pixel size, for example,
a charge coupled device (CCD)."

Depth of field, as we know it in photography, is based on a "circle of
confusion", which in turn, is based on viewing distance, ability of the eye
to discern and the film format.  Depth of focus is not based on any of these
things.

Austin

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