The Notebooks of Raymond Chandler, p. 73

Would it surprise...that the screenwriter regards the camera as his principal character, and that if he did not write a part for that character he would not be writing a screenplay? He doesn't write in camera movements for the benefit of the director or the cameraman, but for his own benefit: so that he may have some knowledge of the acting length of the script; so that he may leave out of his dialogue those effects which the camera can better achieve without words; so that he may have some feeling for the rhythm and pace and movement of the film across the screen. The writer knows perfectly well that the director will not follow his camera directions literally.