[Leica] thinking Zone System

[imagist3 at mac.com (George Lottermoser)]

Tarek,
When I shot film I used all formats:
sheets from 4x5 up to 12x20,
120 rolls from 6x6 to 6x9,
and of course 35 mm.
So I saw Zone System thinking, processing and testing
as the way to achieve predictable results with Black and White.
I use a spot meter to read the dynamic range of the subject;
exposing for the shadow detail I want to preserve;
and developing for the highlight detail I want to preserve;
and then having a pretty good idea of where the other tones will fall.
With 3 120 film backs I was able to carry an N, N-1 and N+1 back.
With 35 mm I'd carry two camera bodies - an N and N-1 body
(and if exposing an entire roll under the same dynamic range conditions
I'd be able to process accordingly ++ or - - or whatever).

Zone system thinking translates to color film as well.
Except only in terms of understanding the dynamic range of the film
and knowing how to expose for the highlight detail you wish to preserve;
and knowing where the shadows will fall to black without detail.
Of course various emulsions have different dynamic ranges.

Lluis and Tarek,
With digital I think in similar terms to color film.
What is the dynamic range of the sensor?
in order to place the highlights where I want them
and know where the shadows will fall.
Further: knowing I have some limited possibilities to extend both ends in 
post processing.

For example:
Expose an evenly lit turkish towel (great texture) as metered (zone V).
Increase the exposure in one stop increments to determine when the highlight 
detail disappears.
Decrease the exposure in one stop increments to determine when the shadow 
detail disappears.
Through testing I have determined that
the DMR has approximately 9.5 stops from deep shadow detail to bright 
highlight detail;
below that is solid black; above that is solid white.
This is about 1 1/2 stops more dynamic range
than the M8; which has about 8 stops from deep shadow detail to bright 
highlight detail.
And the 5D has about 7 1/2 stops from deep shadow detail to bright highlight 
detail.
I say "approximately" and "about" because
different levels and types of lighting; ISO settings; and yes lenses
will have effects on these numbers.

If you want to get really crazy
you can bring these test shots into photoshop
and read the values (just like we used to do with a densitometer).
It's an interesting exercise because you'll find greater separation between 
some zones than others;
a little freaky actually.
(I no longer get that crazy)

Lluis,
I don't know if anyone else is writing about or discussing digital work flow 
in terms of the Zone System.
This is simply my own way of understanding the equipment I'm working with;
and my way of thinking about the more critical work that I do.
Just a natural shift from what I grew up with to what I'm doing now.

Others use the histogram to accomplish the same thing.
I find histograms hard to interpret when the subject has a whole lot of 
black or a whole lot of white in the frame.
Though I can always rely on my spot meter to tell me what is actually being 
recorded and where things will fall.

YMMV

Hope this helps

Regards,
George Lottermoser 
george at imagist.com
http://www.imagist.com
http://www.imagist.com/blog
http://www.linkedin.com/in/imagist