Re: shadow density in zone III

shannon wrote:

> I just realized that I have another burning question about the zone
> system and zone III: what density is zone III in your negatives?

> For a long time I have been following Dick Arentz's suggestion that
> the density of zone III should be about .35-.4. But, as somebody
> mentioned earlier, very dense negatives can also make good prints,
> sometimes very good prints. If I raised the density of my shadows
> to, say, .70, then the highlights would have to be about 1.7, and so
> on.

> Just curious: those people on this list that use densitometers to
> measure their shadow densities: what is your "goal" for your
> shadows? And what is the rationale behind that?

Of course, this depends on your interpretation of the question Christina
originally asked -- what is zone III? If "zone III" means, TO YOU,
"darkest tones in the print that show *some* texture," then 0.35 to 0.40
should be plenty (this actually describes the "bulletproof" negs I
mentioned before). On the other hand, if "zone III" means, TO YOU, "dark,
dark grey with clearly delineated texture,", then zone II -- "darkest tones
in the print that show some texture" -- should be 0.35 to 0.4 and zone III
will end up higher, perhaps 0.7 or so.

In other words, the darkest shadows where you want to see *some* texture,
whatever zone you call them (Ansel called them zone II, I believe, with
zone I being textureless black), should be in the 0.35 to 0.4 range on the
negative (for most films and most shooting conditions) -- up off the toe
just a bit -- and the darkest greys where you want good tonal
differentiation should be higher. [As I suggested before, it may actually
help not to call them "zones" at all.] This also depends on the film --
Kodak's T-Max films have a very, very short toe, so you can put the "some
texture" luminance values a little lower than with other films. Tri-X Pro,
on the other hand, has an "all toe" characteristic and you probably want to
get your "some texture" luminance values higher on the curve so they don't
come out muddy.

> Does it really
> matter what the density of the shadows is, as long as the highlights
> fall in the right place relative to the shadows? Maybe that .35-.40
> thing is completely arbitrary?

Film has a limited exposure range. Traditional B&W negative films can
record 4 to maybe 5 stops on the linear portion of their H&D curve. Below
that is the non-linear "toe" region, which has a lower log D per log
exposure slope than the linear portion and therefore compresses the scene
luminances (shadows) that fall there. Above the linear portion is the
"shoulder" region, where the slope is again lower than the linear portion,
which compresses high-luminance values (highlights) that fall there. Since
the average daylight scene has 10-14 stops of luminance variation, it is
clear that you cannot fit all of the scene luminance values onto the linear
portion of the curve.

By using "minus" development, one can squeeze more scene luminance values
into the linear portion of the curve, at the expense of overall lower
contrast (i.e., less separation of tonal values in the linear portion, and
very low separation in the toe and shoulder regions). Also, modern films
(in particular, T-Max) have longer linear portions. In fact, it is hard to
find the shoulder with TMX and TMY -- density just keeps climbing. So:
Given a modern, long-density-scale film [NOT necessarily
long-EXPOSURE-scale], and a suitable low-contrast printing process, the
answer to this question is a qualified No, it doesn't matter much -- you
can slide things up and down the curve (within reason) with little effect
other than printing time. However, with traditional films (and
particularly with HP5+), you do need to be careful where you place things
because these films do not have excess headroom.

Best regards,

etienne
Received on Thu Sep 29 10:39:03 2005