Hyperfocal distance tables, d.o.f.

[P3D Neil Harrington <nharrington@xxxxxxxxxxxxx>]

John Edmark writes:

>7) Bonus point question: My ektar camera has a "Hyperfocal table" on the
>lense cover. However, it's calculations do not correspond to those around
>the focusing knob of my German Realist, especially at small apertures.
>Which one should I believe?

Whichever one you like best.   ;-)

Seriously, any hyperfocal distance table or depth-of-field scale is based on
some assumption as to the allowable size of the circle of confusion, which
is itself a somewhat arbitrary thing.  The d.o.f. scale on my Kodak Stereo
does not even nearly agree with that on my Revere 33, and both are probably
different from what the markings on your Realists are telling you.  Such
scales and tables are useful only as rough guides at best.

What you could do is take some test shots at a fairly large aperture,
carefully placing subjects at the near and far extremities of the most
"generous" d.o.f. scale or table for that aperture, and then see whether
those subjects appear equally sharp with subjects at the actual plane of
focus, with whatever viewing equipment you use.  Note that final
magnification is one of the factors in determining depth of field, which is
one of the reasons there can be no such thing as absolute d.o.f. correct for
all users in all circumstances.




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