Also, there may be a research aspect involved in each project, depending on the subject matter and historical significance, etc. Gaffers need to understand lighting in relation to the historical context and desired ambience of each production. When working on smaller productions gaffers may have a bigger say in the artistic qualities of the lighting and attend production meetings to discuss lighting needs and special effects with directors. (The EI Group)

Ideally, the gaffer is able to execute his lighting plan while standing with the director of photography and looking at the shot from the camera, while the best boy and electricians adjust the lights. (Christian-Movie.com)

Though the Director of Photography very much has a picture in his mind of the way he would like the scene to look, he draws upon the Gaffers in-depth knowledge of lighting stock to produce the required effect. The gaffer will also understand the logistical implications of how best to do this. (Hubpages Inc. )