P3D "why the 1/30 rule does not work"

[Tom Deering <tmd@xxxxxxxxxxx>]

>Dr. T's assertion that the 1/30th rule will not violate the 1.2mm OFD
>requirement is correct

I liked most of what you wrote, but you've made a mistake above.  Otherwise
pretty okay.  :^)

Example:
near point: 100 mm
far point: 22000 mm
focal length: 50 mm
actual onfilm deviation: 1.2mm
1:30 bad guess: 1.7mm

In this case, using the 1:30 rule will give you way more that 1.2mm OFD.
Look at the diagrams. Every point where #1 is above #4, the 1:30 rule is
OVER 1.2 ofd.

People that are struggling with this, take a roll of test shots.  The math
by itself is hard to grasp, I know, but if you take some measured shots
you'll see the ideas come alive.

Tom




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