This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Correct Angle Of Light For All Subjects. If each individual subject was properly lighted as it was introduced into the group, the completed group, with but a few corrections will be all right, and you may proceed immediately to make the exposure. Hasty grouping would, however, result in lack of individual attention, and considerable time must be consumed at this point in making changes and altering the position of each person to give them proper lighting.
467. If you are not able to light each subject correctly with the source of illumination at your command, the diffusing screen and the reflector must be taken advantage of; and these, together with the proper exposure, will give you as near a perfect result on the individual subjects as is possible to obtain.
Even Illumination. If the light is not properly controlled the subjects nearest the window will be very strongly lighted, while those on the opposite end will not receive a sufficient amount of illumination. Soften the source of light and protect those persons nearest the window from the direct rays by the use of the diffusing screen. Then swing the end of the group, furthest away from the window, around towards the window as much as possible, with due consideration to the proper placing of your camera. Throw as much reflected light as possible on this end of the group, and then by giving plenty of exposure the developed negative should show an even illumination of the whole group.
Proper Lighting For Quick Exposures. Bear in mind that a harsh, contrasty lighting will require more exposure than a diffused light, for, in the former case, the light being very contrasty, the shadows will lack illumination. When the light is diffused the high-lights will be softened and the shadows illuminated by the general diffusion of light throughout the room.
Contrasty Results. Contrasty effects will result if the light has not been sufficiently diffused, if the reflector has not been used and if the exposure was too short.
Spotted Effects. When subjects of both sexes are posed in a group you will have extreme contrast of white and black in the drapery to contend with; the men usually being dressed in black, while the ladies may be in white. Never separate the various subjects so as to have the white draperies mixed in with the black. So far as possible place the subjects in white drapery together and those in black by themselves. If the background is dark it is usually advisable to have the ladies occupy a central position in the group, the men being arranged around them. If the background is very light in color the reverse of these positions should be taken. Avoid too set a formation, however. There should be more subjects in black on one side of the center than on the other, and you should strive toward a triangular form of arrangement of subjects with regard to the color of the drapery.