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.
The Reflecting Screen. You will find more use for the reflecting screen in making Rembrandt Profile Lightings than in any other style of lighting, for you have a larger area of shadow to illuminate. The reflector assists in illuminating the most dense shadows which cannot be reached by direct light. The greatest care must be exercised in the use of this screen, lest you overdo the reflection and produce stronger light in the deepest shadows than you have in the middle tones.
361. In the floor plan, Illustration No. 19, illustrating this lighting, you will observe the position of the reflecting screen, it being placed at an angle instead of facing broadside to the light. Should it face broadside to the light, the reflected light coming from this screen would be more powerful than the direct light and, therefore, the shadows, instead of blending off gradually as they approach the rear of the head, would be choked with a false light. By using this reflector at a suitable distance from your subject, and placing it at an angle so as to partly catch the direct rays of light, it will sufficiently accentuate the shadows. The reflected light will not be strong enough to intrude upon the shadows, but merely assist in producing the desired detail.
Shielding The Lens. When making Rembrandt Profile Lightings, the camera, of course, is directed towards the source of light, and unless the lens is shielded from the rays of light you will be troubled with reflections, resulting in fogged plates; therefore, the lens should be shielded with a hood or funnel-shaped cone, which is attached over the lens. This cone can be made of tin or of cardboard and should not be made shorter than 6 inches, the size of the cone depending entirely upon the angle of the lens. It must be wide enough at the mouth so that it does not interfere with the angle of the lens. The cone should be painted black, on the inside at least. Should it be painted a light color, you would be troubled with reflections from the cone itself - therefore some dead black paint must be used. Any black paint that will not give a glossy finish can be employed. (Detailed description for making a cone is given in Paragraphs 501-506.)
Exposure. The exposure required for this style of lighting is a trifle longer than for ordinary Rembiandt Lighting, for the reason, as before stated, that you have a larger amount of shadow to illuminate and, therefore, require a longer exposure. You, of course, judge the amount of exposure by the appearance of the image on the ground-glass, and your judgment is based upon the appearance of the shadows, paying no attention whatever to the high-lights. In other words, calculate on an exposure sufficient to fully time the most dense shadows. This will require approximately double the exposure of an ordinary Rembrandt front or two-thirds view, and four times the exposure of a Plain Broad Lighting.