In response to Paul Goodwin's question about resolution:
 
Any definition of resolution (Full-width Half-Maximum, Rayleigh's Criterion
1/e diameter, etc) is purely arbitrary.  I see no reason that any would
be, in general, poorly suited for electronic imaging.  Certain definitions
sometimes do fit a particular problem, though, and for calculations of
background rejection and signal-to-noise in confocal microscopy, we used
the 1/e^2 contour to define a focal volume.  This volume corresponds to
90% of the light generated by a point source, so was convenient for our
purposes (se articles by Sandison et al. in Applied Optics, vols. 35 & 37,
and in the 3-D Confocal Microscopy book edited by Stevens, Mills & Trogadis).
For your comparison between deconvolution and confocal, 1/2 widths seem
as good as any other definition, but what you really need to compare is
not resolution but information content (signal-to-noise).
 
Unfortunately, this is not a trivial problem. . .
 
                                Dave Piston
                                Vanderbilt University