A man is able to discern up to 300 stages from white to black. One can see up to 30 tones in black-and-white photography (a long tonal scale) or no more, than 10 tonal tints (a short scale). Moderate quantity of colors makes a picture more expressive. The exclusion of intermediary colors allows get rid of minor details, and pictures, accomplished in some definite tonality make a stronger impression.
Light colors are associated with calmness and joy, while dark colors create the effect of expression, circumspection and dramatic tension. Portraits or landscapes are usually executed in dominating key in order to achieve greater expressiveness of the image.
Dark Tonality (Low Key)
It is characteristic for the image in Low Key style that most part of the image is formed by dark, sometimes black elements, but most details are well discernible, and light areas are always bright and clear. The intermediary tones are expressed weakly, by dark sections of the tonal scale. Presence of separate bright spots is the necessary requirement. All the elements, included to the picture, with the exception of those, creating a key (tonal) accent, must not greatly differ from each other in brightness. Counter, counter- side and side light is most often used for the illumination. Evening landscapes are often executed in low key, including light sources to the picture.
Light Tonality (High Key)
It is characteristic for the image in High Key style that light-gray and pure-white colors constitute the most part of the image. The necessary condition is presence of at least insignificant completely black elements, which contribute the necessary tonal (key) accent to the image. The correlation of the colors (tones) of the picture shall be determined not only by the illumination, but by the object itself, and that is why the object must be mainly light. It is impossible to make the picture of a dark object against a dark background in high key. Snow-clad landscapes, water surfaces, and portraits can be executed in the high key. To make pictures in the high key the objects must be well and evenly illuminated. In case of weak illumination it is impossible to reproduce separate dark spots with light gray colors. During studio shooting of portraits it is necessary to create soft diffused illumination, which doesn’t create dense shadows. The difference in brightness at various sections of the object must not exceed one stage of the exposure.