Frame key on a photograph can be determined by correlation of black, white and grey fields in it. A man is able to distinguish up to 300 grades from white to black. In black-and-white photograph it’s possible to find 30 tones and less than 10 tone tints. Temperate quantity of tones sometimes makes the shot more expressive. The exclusion of tints helps get rid of secondary details, and the shots made in a certain key make stronger impression.
Light tones are usually associated with joy and calmness, the dark ones create the impression of expression, tension, vigilance. Portraits or landscapes are usually implemented in dominating key to achieve great expression of a photograph.
Low key. Low key style photographs can be characterized by the fact that the major part of the image is formed by dark and sometimes even black elements, but the majority of details are well discernible and light areas are bright and clear. Tone tints are slightly evinced by dark parts of tone scale. A necessary requirement is the presence of detached bright areas. All the components included in the frame, except the ones that make key effect, aren’t supposed to differ in brightness much. You can use front, front-side or side lights. This key is usual for the night and evening scenes with the inclusion in the frame of the illuminant.
High key. Photographs in high key style are characterized by the fact that the major part of the picture is formed by light grey and white tones. A necessary requirement is the presence of any, insignificant but absolutely black components, which add to an image the essential tonality emphasis. The correlation of the tones of survey is defined not only by the light but the object itself, that’s why the object should be generally light. It’s almost impossible to create the image of dark object on dark background in high key style. You can use high key to create snow landscapes, water surfaces, portraits. You also need to light up your object or model evenly. Using bad illumination certain dark areas can’t be reproduced with light grey tones. When in a studio try to create soft diffused light for your model so that the light doesn’t make dense shadows.