P3D Re: Dodging and burning

[Paul Talbot <ptww@xxxxxxxxx>]

John W Roberts wrote:

> since dodging and burning just affects *parts* of the print, I would
> think that if the specific parts affected don't match up fairly
> closely, your visual system might pick up the local dfferential.

Based on my experience, I would have to disagree.  I have a large
number of stereo prints taken with a severely light-leaking Realist
(before I knew about that problem).  I am astonished at how much the
huge orange streak on the right side image fades when viewing the
pair in stereo.  On only the worst of the streaked shots is the
streak a major problem.  (I would not enter the streaked photos in
a competition, mind you, but they are not 100% ruined as I would
have expected.)  Apparently Mother Nature gave us two eyes for
more reasons than just stereopsis.

One thing I've wondered about however:  would the streak on the
right side image be a lot more of a problem for someone who is
right-eye dominant?

> Does anyone have "rule of thumb" numbers for the number of density
> steps "typically" available on a black and white print? A color print?
> A color slide?

Not quite sure what you mean by "density step."  There are of course
the 9 zones of the Ansel Adams et. al "Zone System."  But those are
full stop steps, and the human visual system can easily distinguish
density variation in 1/3 stop increments (except perhaps at the
extremes.  There is very little difference between Zone VIII and
Zone IX, for example.)  So perhaps ((7 x 3) + 2) = 23 steps, for
a black and white print, is what you are looking for?  It is somewhat
less for color prints, and less still for color slides.  I seem to
remember 5 Zones as the number typically cited as the range of color
slide film, which would give somewhere between 11 and 15 steps as
I've interpreted what you are looking for.

Someone other than me can probably tell us how many gradations are
on the Kodak test strips.

I hope this helps.

Paul Talbot


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