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.
Backgrounds. Large portieres or curtains - provided that they are not too dark - make good backgrounds for group pictures. If extremely dark they prolong the exposure. Usually, sitting positions are the easiest arranged; and then, too, when your subjects are seated lounging, or even sitting erect, they hold their position with more ease, and there is less liability of their moving during the exposure.
Diffusing The Light. For groups you will require less diffusion of the light entering the window than you will for single portraits, for you naturally work farther from the source of light. However, some diffusion is necessary in order to spread the light over the entire space.
Reflecting Screen. Frequent use of the reflecting screen should be made, and it should be so arranged, and placed at such an angle, as to reflect the light from the front into the faces of the group, thus giving more roundness.
Practice Work. For practice work we would recommend that not more than two or three figures be arranged in one group and where two windows can be employed you should make use of them both and arrange your subjects so they, partially at least, face the source of light.
454. Having carefully studied the instruction regarding the arrangement of figures, controlling the light, use of the reflecting screen, etc., proceed to arrange your group. For your first experiments you should not select subjects gowned in contrasting colors. The more uniform the colors the easier it will be for you to control the light. Place your principal figure first, in a position where it will receive fairly good light, and arrange it about as you would if you were making a Plain Portrait Lighting. Then introduce the second figure, arranging it in a like manner but posed differently. If a third figure is to be admitted be sure to have the figures placed so that the heads will not be on a straight line. The farthest subjects from the window should be arranged more facing the window, thus giving all an equal illumination.
455. See that the light falls evenly and that all members are uniformly illuminated. If the light seems too harsh and strong, make use of the diffusing screen in the window. If the windows have lace curtains, draw them slightly before the window, sufficiently to diffuse the harsh light and distribute the illumination equally over the entire group. You will find it necessary to make free use of the reflecting screen. Place it at such an angle that it will reflect the light into the front of the face of the subject. The camera should be placed so as to secure a proper lighting on the group. This will give you a position near the window. Focus with an open lens and only stop down enough to produce a reasonably sharp image throughout. Before making the exposure, see that each member of the group has an easy, comfortable, as well as natural, position and then make your exposure. You can judge the amount of exposure required by the appearance of the image on the ground-glass. You will find that it will usually require double the exposure necessary for single portraits and sometimes more, all depending on the source of illumination employed.
456. Do not make less than two negatives, giving one almost double the exposure of the other, and on developing the two plates you will have a good key to the proper exposure of groups made under like conditions. Make proof prints from both, noting all data pertaining to their production on the back, being particular to note the amount of the exposure given, the time of day, stop used, etc., also the conditions of the source of light employed, whether diffused or open. File these proofs in your proof file for future reference.