P3D DOF Table on Realist lens cover varies among samples!

[Paul Talbot <ptww@xxxxxxxxx>]

Michael Kersenbrock wrote:
 
> My Realist says that f/16 with a near point of 4-feet,
> the far point is at Infinity!  This particular (older)
> Realist doesn't even have a DOF scale on the focus knob
> (has a chart under the lens cover).
> 
> That was the crux of my original point (Realist maybe fibs
> a little too (not your realist, my realist)).

I don't know the exact theoretical DOF range for the Realist,
so I can't vouch for the veracity or lack thereof of the scale
on your lens cover.  But, hey, I just remembered, one of my
Realists is an older model, (the DOF scale on it was a retrofit)
so let me go check....

Hmmm.  Mine says at f/16 to set the distance marker to 10, and
you get DOF from five feet to infinity.  Other useful readings:
for f/11, set to 14 feet for DOF from 7 feet to infinity; and
at f/8, set to 20 feet for DOF from 10 feet to infinity.

So now I'll change the subject line so folks who have tired
of this debate don't miss this interesting little tidbit!  ;)

(My earlier estimate of 4.75 feet to infinity was based on a
slightly different interpretation of how to read the scale,
one of the hazards you pointed out earlier.  But that is a
"close to the edge" issue, as opposed to the core issue.)

So your Realist has a different DOF table than mine, which
might be "a little fib;" I would surmise it may be due to
a poor decision to round down "4.x feet" to "4 feet" instead
of more conservatively rounding up to "5 feet."  Would it be a
good guess that you have an older model than mine, and David
White corrected this initial poor judgement?  I can find no
reasonable explanation, however, for the wildly optimistic
DOF markings of a Revere.  (Although I'm sure by now BobH is
tempted to remind us that Revere was a pot maker!)  The markings
on the Rever are, IMO, pure fantasy, whereas the markings on
the Realist are pretty realistic.  Forgive the pun.  ;)

(The DOF table numbers I state above come from S/N A35629.)

Paul Talbot


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End of PHOTO-3D Digest 2529
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