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.
Position Of The Light. To properly illuminate a face, the light should all come from one source and should fall at an angle of about 45 degrees.
Plain Portrait Lighting. To secure a Plain Portrait Lighting the lamp should be placed 2 1/2 feet above the sitter's head, 2 feet in front and 3 1/2 feet to the left of the subject. Have the face of the sitter turned so that when you stand directly between the lamp and the sitter, the tip of the nose just breaks the outline of the shadowed cheek. (See diagram No. 39 of floor plan.) The amount of powder required will depend upon the surroundings and also the size of plate used. Usually from 1/16 to 1/8 of an oz. will be sufficient if a white reflector be placed about four feet from the sitter. In making this lighting it will seldom be necessary to shade the lens. In Illustration No. 40 is shown an excellent example of the results obtained with the Nichols' Flashlamp.
Rembrandt Lighting. For Rembrandt Lighting the lamp is placed in almost the same position as for Plain Lighting, but the camera is moved so as to secure a view of the opposite side of the face (shadow side). See diagram No. 41. A white reflector should be placed about five feet from the subject and directly opposite the lamp. From 1/8 to 1/4 oz. of flash-powder will be necessary to give the proper amount of illumination and the lens should be shaded as previously directed.
Groups. In making large groups, the lamp may be used without a screen, but it is always best to use the screen as softer results will be produced. If the ceilings are sufficiently high the lamp should be elevated enough so that the light falls at the proper angle on the subjects in the center of the group. The lamp must always be placed near enough, in front of the group, so the shadow cast from any one face is thrown back of it instead of on the person sitting next. Avoid grouping close to the wall, as shadows cast on it are anything but pleasing. The group should be at least four feet from the wall or background.
Illustration No. 40 Child Portrait Made with Nichols' Flash Lamp. See Paragraph No. 508.
Usually in the ordinary home there is sufficient illumination from gas or electric-light to light the subject so that you can obtain a focus. If the general illumination in the room is insufficient to light the subject, have an assistant hold a lighted lamp or candle close to the face of the subject; you can then focus more accurately. If a group is being made, focus on the central member and the rest will very likely be sufficiently sharp.