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.
Background. Dark backgrounds should be employed. Where a graded ground is used - one in which the tone blends from dark to light - it should be so placed that the dark end will appear back of the light side of the face, the light end being on the shadow side. The effect of contrast will in this way be accentuated, making the high-lights more forceful, the darks more rich. At the same time the actual contrast has not increased, but is kept within bounds; so with proper exposure the shadow detail will be recorded before the high-lights are over-exposed.
Reflecting Screen. The handling of the reflecting screen for this style of lighting requires much more careful attention than when using it for Plain Lightings, although the greatest care must be exercised at all times in securing just the proper amount of reflected light, and no more. However, you should make free use of the reflecting screen, placing it as close to the subject as necessary to obtain the proper illumination. Bear in mind, there should be no harsh lines existing between the high-lights and shadows. A gradual blending from the highest lights to the most dense shadows should be present.
315. The reflected light should, as previously stated, be simply a diffusion of the direct source of light. Therefore, the angle at which the reflector is placed is of vital importance. Flatness and, in fact, complete ruin of an otherwise good attempt at Rembrandt Lighting is the result of reflected light being cast too strongly on the shadow side of the face.
316. If one end of the reflector is nearer the light than the other, the end nearest the light will throw the strongest reflection. When placed at the proper angle it will cast the strongest reflected light onto the front of the face. From this it will be seen that it is essential to make various trials with the reflector in different positions, not only placing the screen at different angles to the light, but also near and distant from the subject.
Exposure. The exposure for Rembrandt Lighting requires approximately double that for Plain or Broad Lightings. As it is better to err on the side of over than under-exposure, do not hesitate to give plenty of time. From six to eight seconds is usually required, all depending, of course, upon the amount of illumination, as well as the speed of the lens employed. If an anastigmat or portrait lens is used, one to three seconds would be sufficient exposure when using the lens wide open.
Developing. Negatives of Rembrandt Lightings are developed exactly the same as any other style of lighting, taking it for granted that they have received the proper amount of exposure. The shadows must be fully timed. If this is done the negative will develop evenly and the detail in the shadows will build up proportionately to the increase of density in the high-lights, and no difficulty should be experienced in producing a soft negative. If under-timed, decided contrast and weak shadows will be the result. On the contrary, if the negative is fully exposed, even if a trifle over-exposed, the addition of a drop or two of Bromide of Potassium, or the use of old normal developer, will enable you to easily control the development. It is very seldom necessary to restrain negatives of Rembrandt Lightings in the developer, for in many cases you will have under-exposures to deal with. The latitude in exposure in Rembrandt Lightings is much greater than with any other style of lighting. It is, therefore, permissible to give fully one-third more than the normal exposure, and yet produce good results.