Proper Studio Exposure and Lighting Management
There are two methods, each distinctly different from each other, of arriving at precise exposure of the photographic emulsion. The fist method, a two-step method, is used with every change of emulsion, or more specifically, with each gamma factor as given to us by the manufacturer. This method, in turn, allows us to arrive at and formulate the second, single-step method of a particular emulsion involved. Each change of emulsion and/or gamma requires the application of the two-step method, from which the one-step method originates.
The Two-Step Method of Proper Exposure of Vericolor III
The film base of Vericolor III negative material is orange in color. This mask is necessary to help purify the colors it supports upon its base. This mask has a density of .12 to .18 and must be neutralized or it will print through to the paper as cyan or green in the dark or black areas. A color is neutralized by its complementary color of the same density. An easy way to remember the negative color basics and their complements is: Red Cadillac/BY/General Motors. More specifically, Red over Cyan: Blue over Yellow: Green over Magenta. So we are advised to use .30 units of cyan to render the orange mask as a neutral grey. Our first objective is to introduce enough fill light into the room so as to give a transmission densitometer reading of .30 in the darkest areas of the negative (.15+.15). For this we need to make a fill-light test to arrive at an F-stop as our permanent working aperture (applies to both high key and low key).
Let us proceed by seating a model before the camera, preferably wearing a black textured sweater (or a black textured material laid in folds over what would later be the shoulder in shadow). The subject should be holding a Macbeth Color Checker or the color-scale insert from the Kodak Professional Data Guide. The model’s face and color chart are placed 45 degrees to the camera axis to prevent possible reflections and/or flare. The subject and color guide are shot in tightly with lens racked out to account for bellows type factor. Also, use a fast shutter speed of at least 125th of a second to prevent the recording of environmental illumination. Our objective now is to arrive at a proper F-stop that will give us a reading of .30 in the blackest black of the negative, and a reading of .65 off the middle grey on the color guide. (This latter reading will be .20 more with the main light on.)
Set up the fill light not closer than nine feet from the subject back to or behind camera position. Nor further than 15 feet as we lose control of our light spread. I find that most operators use 12 feet as their standard. If you use a lens hood, vignetter, diffuser or other lens supplements, these should be placed before the lens to be included in the test. Switch on the shadow fill light and, starting with f/4, expose every 1/2 stop from f/4 through to the smallest opening. Have the film processed and have the lab give you a reading of the deepest shadow area as well as the grey-card area on each frame. Be sure they make the reading through a status “M” red filter (as opposed to a status “A” red filter, which is used on transparency material). Your working aperture will be that which resulted in the .30/.65 grey-card reading.
For the sake of illustration, let us say that we have selected f/8 as our working aperture. We now set our aperture for f/8 (and leave it there) for the next part of the test. Let’s add a second light (main light). The main light source is used to establish lighting ratio. In establishing a working intensity for the main light, we must first be made aware of the fact that the intensity (or intensities) we use must be such that detail is maintained in both the shadow and the highlight area. Printing paper will handle a density range of 1.00. We know that at f/8, our fill is giving us a .30, which, in turn, is giving us shadow detail in the darkest areas of the negative. Therefore, we can raise the intensity at the other end to 1.30 and maintain detail in the highlight areas. As a ready reference, the diffused highlight flesh density on the forehead of the subject is at optimum saturation at 1.10. This is one stop (1.30–.20) below the upper detail limit.
We now prepare for the highlight density test by placing our subject at 45 degrees with the color guide as in test 1, leaving the fill light switched on and placing the main light 45″ away from the subject. Adjust the main light as you would if you were making an actual sitting (feathering, etc.). Our objective here is to find out, using a constant F-stop (our hypothetical f/8), and the light at 45″ away from the subject throughout the test, which watt-second power will render a 1.10 diffused flesh-tone saturation and a .80 grey-card density reading. Starting with 25 watt-seconds, an exposure is made and noted at the color guide area (the same way in which the lens openings are recorded in each frame in the fill intensity test). Proceed to shoot and record each of the watt-seconds (i.e., 50, 100, 200, respectively). Have the film processed and read in the same manner as with the fill test reading, except we are looking for the ideal watt-seconds that will produce the desired 1.10/.85 readings.
Again, for the sake of illustration, let us say that we arrive at 50 watt-seconds as our ideal watt-second setting. With the 1.10 highlight density and a .30 shadow density, we have a negative that will print well within the parameter range of the paper. Since the paper can handle a 100 density difference (we used up only .80!), we could go to 1.30 (to the 100 parameter upper limit) and still maintain detail in the highlight area. A raise in highlight density would give us whites without detail (useful in hi-key backgrounds where detail is not wanted). If you cannot vary the watt-second power on your present equipment, you can still accomplish the highlight density test by varying the distance of the main light starting with 45″, 56″, 63″, 80″, 90″ and 125″. Similarly, use the distance that gives the 1.10 flesh density and the .85 grey-card reading. 3/4 and full-length can be a problem here, as lens openings would be used to compensate for the lack of watt-second power, causing somewhat of a control loss and adding a variable that should be avoided. On the variable watt-second units, however, a ratio can easily be maintained by increasing the watt-second output in direct proportion to the distance as follows: 45″: 50 watt-seconds, 63″:100 watt-seconds, 90″: 200 watt-seconds, 125″: 400 watt-seconds. The highlight flesh density is maintained at 1.10 throughout the different distances.
The fill light is a shadowless non-specular source of light needed in basing the film exposure and complementing the ratio of the main light. It is the foundation of scene brightness for both low key (dark tones) and high key (high tones). The main light shapes, molds and projects the five facial planes of the face, namely, the nose, chin-jaw area, forehead and cheekbones. Moving the light straight in and out does little to project these planes. But rather, as we move the main light away from the camera axis, we begin to create roundness and dimension to the face. The nose is the center of the universe. Then the cheekbones, chin-jaw area and forehead. As we shift the light in a lateral direction, we observe the pattern of light at the nose area. A butterfly shape beneath the nose to a loop, to a 45 degree lighting where the nose shadow joins the facial shadow creating a triangle of light beneath the eye opposite the main light. The loop light is also known as a modified butterfly. The loop light is perhaps the greatest used light in portraiture. It is the “play it safe” lighting form, and rightfully so. The size of the loop is determined by the depth of the bridge of the nose. Another factor to consider is the width of the face. A wide face can be made to appear narrower with a 45 degree (Rembrandt) lighting. In any event, the shadow of the bridge of the nose must never enter the white of the eye on the shadow side of the face unless we are attempting to create an illusion of a smaller eyeball.
Once the facial lighting pattern is established, the light is then feathered both vertically, then horizontally, in that order, to even out the illumination of the face. Feathered correctly, the center beam of light (the umba) crosses in front of, rather than right on, the subject’s face. The face is receiving its illumination from the camera side of the reflector (the fanumba). Different lights give different contrasts.
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