While the cameraman is shooting the film, he takes care to maintain a constant photographic quality throughout the whole of his work. When the film editor comes to cut the material he must guard against joining two shots in which the key of lighting is noticeably different.
The sheer physical difference in the light and shade values of the two
shots will draw the specatator's attention to the transition and result in a
With the cameraman constantly in control of the lighting and the grading of the prints, this problem of matching shots according to their tone is generally not great. In a documentary or compilation film, where the material has often been shot by several camermen working separately, it becomes much more acute.
Equally, the editing of colour films sometimes presents great difficulties in matching the colour values in adjacent shots. This is, however, primarily a problem for the art director, cameraman and colour expert and is in most cases outside the film editor's control.