P3D Rever DOF scale: stereo fantasy

[Paul Talbot <ptww@xxxxxxxxx>]

(Changed subject line because I bring this up for the benefit of
new stereophotographers, not in relationship to the previous thread.)

Greg Wageman wrote:

> But, consider the depth of focus scale on our stereo cameras.  At f/16, the
> hyperfocal table on the Revere indicates that the image is sharp from about 3
> feet to infinity.

We have to be very careful how we express a range of DOF.  Be precise
on the close range and save "about" for the distant range whenever
possible, because the falloff of focus is non-linear with distance.
If infinity needs to be one endpoint, don't be too casual with the
approximation of the near point.  According to my Revere, the near
point limit is about 3-1/2 feet with infinity at f/16.  With the
near point set as 3 feet on f/16, my Revere claims DOF extends to
about 40 feet.  Even this is pure fantasy!  Compare to the DOF scale
on the Realist, which indicates DOF from 3 feet to 8 feet at f/16!
Three feet to eight feet, versus three feet to forty feet is a
huge difference...and it is not because Revere discovered some
great magic to enhance DOF!

Be very wary of those DOF scales on the Revere!

Paul Talbot


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