[Leica] OT: Digital Zone System

[Martin Howard <mvhoward@mac.com>]

I've decided to learn (properly!) the craft of photography.  I'm 
starting with exposure and development: I've done these before, so this 
isn't totally new ground to me.

I find that thinking in the Zone System is a useful tool.  I think of 
zones in terms of tonality in the print, rather than in terms of 
densitometry, in terms of placing a chosen scene luminance in a zone, 
seeing where the other luminances fall, and I get the principles of 
expanded and contracted development to fit the contrast range of the 
scene to the contrast range of the negative.

However, and this is where the monkey wrench gets thrown into my 
thinking process, I work (unfortunately) with a digital darkroom these 
days.  While I can perfectly understand how to calibrate my printing 
process so that I get Zone 0 to Zone X in the print, the scanning 
process is throwing me off.

I use a negative scanner in which I can set exposure manually or 
automatically.  What I would like to do is ensure that I develop my 
film such that I'm certain that the scanner will be able to scan all 
the tones correctly.  But I'm not sure how to go about doing this.  If 
I scan clear film (base+fog) then all I get is a frame of noise, not a 
frame of a single colour.  If I were to shoot a scene with a Kodak grey 
card in it, then I don't know how to ensure that it will scan as Zone V 
each and every time, since the scanner (even on manual exposure) seems 
to compensate how it maps the digital levels 0 -- 65,535 to the 
negative density differently depending upon the distribution of those 
densities in the negative.

Am I missing the point here?  I would like the scanner to capture the 
widest possible range of densities (within the capabilities of the 
scanner), and to be absolutely certain that it will do this regardless 
of the range of density in the negative.

If it matters, I'm using a Minolta Dual Scan III and the Photoshop 
plug-in for this scanner, although I'd like to understand the general 
principles at work here.

M.

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