Shadow Detail – Part I

Expose for the shadows and develop for the highlights.

A good piece of advice for a beginning photographer. What this teaches is that shadow areas need to have enough exposure so that there is something on the negative, i.e., detail in the shadows and not just flat black. You can’t print it if it’s not on the negative or in the digital file! So, one sets the exposure so that shadow areas register two or three stops above flat black (or no light).

For film users, develop for the highlights means to process the negative so that the opposite, the lightest value, does not go to total white, but still has “detail in the highlights”. Digital exposure for highlights is another discussion.

Ansel Adams, and others, codified this in the “Zone System”, a method to (among other things) control the exposure and development of black and white film. To oversimplify: There are 11 “zones” from Zone 0 (total black – clear on a negative) to Zone 10 (total – or “paper” white – or maximum density [black] on a negative). Zones 1-9 (In Adams’ writings, et al, the Zones are in Roman Numerals) are considered the “printable” dynamic range, with only zones 2-8 showing any “visible texture”.

zone

Each zone is one stop of exposure or value more or less than the adjacent zones. Zone 5 is “middle grey”, and is what light meters are (theoretically) measuring for. In its simplest application. when metering a scene, one generally adjusts the exposure so that the darkest area (often a shadow) receives enough exposure to be printable at Zone 3. Then, development is adjusted so that the lightest area that one wishes to retain detail will settle out to about Zone 7.

That’s the goal. Many sheet film users, who develop each sheet of film separately, and thereby adjust their development for each, can use the Zone System in its purest form. However, roll film users have to compromise, as we cannot develop individual negatives on a roll, they all get the same processing.

Real life throws in more complications. The light in scenes being photographed, especially outdoors, can often span way more than 9 stops of value brightness. Black and white film may record more than 11 stops if exposed and developed carefully. So, a brightness ratio of more than 10 or 11 stops is “compressed” onto the film, or a decision has to be made what to let go off the scale on either end. (A light source in the image, for instance, will usually be so bright that it is off the scale above Zone 10.)

Silver gelatin printing paper has even less range, and whatever is on the negative has to be compressed or manipulated even more in the print. The photograph below (bright sunlight through an opening in an outdoor overhang) was exposed well enough so that there is detail in the negative for the center, sunlit area; and the shadow around it.

trapazoid neg

But printing both on paper is a challenge. When printed “straight”, either the shadow goes completely black,

trapazoid neg black

or the light area washes out.

trapazoid neg white

I have used this negative in teaching to demonstrate just this problem, and some of the solutions.

We accomplish such solutions in the darkroom by a combination of contrast grades, dodging and burning, exposure variations, and chemical development manipulations. Digital workers do similar things with software. But, the fact remains that if it is not on the negative or in the digital file, i.e., it’s too dark or too light, it can’t be printed. Color materials generally have less latitude than black and white, with color slides being worse than color negatives; and digital has historically suffered as well, although improvements in dynamic range captured by digital sensors are constantly being made.  (Shoot raw!)

From a craft standpoint, a skillfully made print from a well exposed negative or digital file – one with both good shadow detail and detail in the highlights – is a beautiful thing to behold. Hence, the axiom “Expose for the shadows and develop for the highlights” has became a rule for many photographers. It’s not a bad rule. It is especially valuable when metering a scene to determine optimal exposure for the film or sensor.

But, then there’s the print. The prior post (see: Less light) discussed shadows, and showed some examples where the shadows were essentially the subject.  But what if a shadow is not the subject, but is just a shadow?

Next post: Shadow Detail, Part II: Shadow detail is over-rated!

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