Digital BW, The Print

Bob 

Thanks for this - and to Steve and others who are helping me come up this
learning curve.  I have a couple of questions in response to your comments
below:


> From: "B. Campbell" <bellis60@...>

<snip>

> All traditional photographic papers have roughly the same contrast range, abut
> 1.8 - 2.1 (Ilfachrome had about the highest at 2.4).  The differences among
> them are in how that available range is apportioned among the shadows,
> midtones, and highlights, which is what a chracteristic curve will show you.

I now understand that the contrast ratio of a photographic paper is its
gamma - or put another way, gamma is contrast.  A paper could, therefore,
have a higher or lower dynamic range (reflection density range) and still
have the same contrast.

<snip>
 
> Density is measured in log units. .30 log units equals one stop.
>

Got it.

<snip>
 
> Hope this helps and that I'm not talking down to you..
> 

Certainly not!  I am sitting here with Normen Koren's website in front of me
and Ansel Adams' book The Print open to the discussion of the zone system on
my left and coming up a big learning curve!

A couple of additional points for me to check with you and others:

Ansel's zone system uses a 10 Zone range of which 8 are considered "dynamic
range".  Presumably this was a  useful number because for the printing
processes employed by him and others at the time, this range of mid exposure
+/- 4 stops suited the general dynamic range of the papers/chemicals used in
the printing process.  If papers had a broader more usable dynamic range he
might have gone to a, say, +/- 5 stops terminology and placed the mid point
at Zone VI.  Do I have this thinking correct?  If Ansel were stuck with the
dynamic range we can achieve from an inkjet printer on matt paper presumably
his zone system would have had just 5-6 zones?

Further, I understand his philosophy of making the best negative was driven
with the knowledge of his printing "restrictions" in hand and the knowledge
that he had a more limited (at least in comparison to digital manipulation)
opportunities to alter the tonal range significantly after the shutter had
been released.  (He did of course have access to negative processing
adjustments and different paper grades with different contrast ratios etc.)
But I think it is fair to say that he strived for the best negative with a
"down the middle of the fairway" print process in mind.

Digital (particularly when playing with 12 bits or more) provides us with a
great deal of latitude over tonal range post the shutter release - either by
manipulating the RAW data with a transformation/contrast curve or by
altering the data once it has been processed by the RAW converter with a
stock gamma and white point.  Some have mentioned that we need not be so
concerned any more with the restrictions of the print at the time of shutter
release because of this increased flexibility.  We can pick and choose later
which parts of the data we choose to reveal and which not. I understand
this.  

But are digital photographers really abandoning the sort of forward thinking
that Ansel has proposed?  Are people really saying capture the maximum tonal
range possible, conscious of the linearity of the sensor, by simply using
evaluative metering and dialling in exposure compensation such that the
histogram pushes as far to the right as possible without clipping? I guess a
proponent would argue that at least this method means we have the data
stored and as printing technology improves we can reprint the print and
present a better image with more of the available tonal range presented.
But don't you end up losing the benchmark of knowing at the time of shutter
release that you have defined the part of the scene that will print mid
grey?  Doesn't the final print then become simply a complete artistic
interpretation affected by memory and other factors? (Eg "I think I wanted
the door in my composition to be mid grey", or "I don't care what shade of
grey the door was - it looks better this way now.")  I am not saying this is
a bad thing just trying to determine what boundaries have been crossed.

I have not made it through all the materials you guys have given or pointed
me to and I will keep going but this lurks in the back of my mind as I go
through this.

Thanks again

Steve