TONAL SCALE

Tonal scales are the blacks, whites, and shades of gray we have available in black-and-white image making. Your most important technical job when you take a picture is to record as full a range of these tones as possible. You can't create tones (especially the information they hold) on the print that don't exist on the negative or in the image recorded by the digital sensor onto your memory card.

When you make an exposure you are recording brightness values that exist in the scene. Bright areas are called highlights and darker areas shadows. The “significant highlight” is the brightest area in the scene that contains texture (as opposed to “spectral highlights”, which are glints of light like that those sparkling in a pond in the late afternoon); significant shadow values are the darker areas in which detail or image information appears, as opposed to deep shadows, which are just deep tones without detail, like the shadows cast on a bright day.

Of course, your recording contains more than just bright and dark areas-there's a whole range, or scale, of tonal values in between. These go from near-black to near-white, with all the myriad shades of gray. Some photographers differentiate these shadings into eleven Zones, numbered 0 through 10 (with 0 being pure black and ten being pure white.) There are of course many more steps or better stated a full gradient possible. Most importantly, regardless of how you slice it, the tonal scale recorded during an exposure defines the range of possibilities within the print. Have a broad scale of tones, or in film, densities, and there's a good chance you can generate same on the print. There are simply more options, both creative and corrective, when you record as many of the brightness levels within the scene as you can, and as the medium allows.

Photo copyright George Schaub, 2010. This print shows a full range or scale of values from deep shadows to textured highlights.