Digital BW, The Print

----- Original Message -----
From: "Kevin Gulstene" <kevin@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Thursday, March 28, 2002 1:05 PM
Subject: Re: [Digital BW] Dynamic Range Definitions and Print Tones


> On 3/28/02 12:04 PM, "Martin Wesley" <mwesley250@...> wrote:
>
> >
> > ----- Original Message -----
> > From: "Kevin Gulstene" <kevin@...>
> > To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> > Sent: Wednesday, March 27, 2002 11:27 PM
> > Subject: Re: [Digital BW] Dynamic Range Definitions and Print Tones
> >
> >
(snip)

> > Thank you for the nice concise explaination. My concern with a print is
that
> > the "smallest possible amount grayer" will go to zero if the print or
medium
> > is continuous in tone which renders the expression meaningless for this
> > application.
>
> I think I am with you on this.  While I agree the "smallest possible
amount
> greyer" will get much smaller as the sensing technology improves, there
will
> always be some level at which there is a smallest possible amount (ranging
> from the practical limits of our eyes to the other extreme of quantum
> whatevers). More importantly we should keep in mind the purpose of the
> textbook definition which is to characterise a system and not an
attribute.

As we get deeper into things, there is the risk of neglecting the actual
reality in favor of our measurements and equations. You always need to step
back and do a general sanity check on your numbers and what they tell you.
>
> The text book definition of Dynamic Range is appropriate for measuring a
> system.  We would have a similar problem discussing the dynamic range of a
> negative.  On the other hand it is quite easy to see how the term applies
to
> a scanner.  In the context of a scanner (a "system" for measuring the
> density of a negative) Austin's Diagram makes perfect sense.  There is a
> minimum density of the negative (film base + fog) and a maximum density
that
> can be read by the sensor, and there is a "smallest increment of grey"
that
> can be measured by the "system".  This smallest increment is determined by
> the system (# of bits in the ADC, the 'noise' introduced when amplifying
the
> signal from the sensors, etc).

Exactly. I think one of the confusions is that you can talk about the
potential dynamic range of a type of film in conjunction with a type of
developement as a system in these terms but not the individual negative once
it is exposed and developed unless you still have the original scene to
compare it to, which you normal don't.  I keep fair records of my view
camera work and will record light meter readings in the form of zone
placements for at least two areas in the scene so I could relate a given
negative back to these values and talk about how well they were or weren't
captured in numerical terms but it is still very crude. But it is enough to
help me adjust my developing conditions in the future.
>
> In my mind, it is much easier to apply the text book definition (which I
> think we agree can differ from the common use definition) to a system for
> measuring an attribute of a print, than to the attribute of the print.

This is one of the points I have been trying to make. The measurements are
not the print and the noise of the measurements is not the noise of the
print.
>
> Ouch, I have to go find the Tylenol now.

Try 4 Advil.

Martin