Reversed 50mm DOF tests using Canon G5 with Pentax 50mm f2.0 lens.
Pentax lens parameters:
f2.0 reduce vignetting,
focused to infinity

Canon G5 parameters:
Focal length = 28.8 (140mm 35mm equivalent).
f3.0
f5.6
f8.0
Same focus used on all 3 images.

Scale: millimeters
Camera angle: ~45 degrees relative to scale
Actual DOF = Measured DOF / cos(45 deg)