Cinematography-Theory-And-Practice

Blue-Only AdjustmentProfessional monitors have a blue-only switch. This turns off thered and green, leaving only the blue (Figure 9.17). If your monitordoes not have a blue-only switch, you can use a piece of blue gel (fullCTB) or a Kodak Wratten #47. View the monitor through the gel.If you see any of the red, green, or yellow colors, double the blue gelover to increase the blue effect.By using the blue-only switch or a piece of blue gel, you haveremoved the red and green elements of the picture. Only the blueremains. If the hue is correct, you should see alternating bars ofequal intensity.turn the chroma or color until the gray bar at the far left andthe blue bar at the far right are of equal brightness. You can alsomatch either the gray or blue bars with their sub-bars.of equal brightness. You can also match either of them withtheir sub-bars. Now the four bars — gray, blue, cyan, andmagenta, should be of equal intensity. The yellow, green andred should be completely black. See Figures 9.17 through 9.19for monitor views of this procedure.Once you have set up your monitor, leave it alone until you moveto another location or viewing conditions change. Unless you have awaveform and vectorscope, it’s the only instrument you have to seehow accurate your video is.CAMERA WHITE BALANCEJust as we use film stocks of different color balance and camera filtrationto adjust film shooting to different color conditions (daylightor tungsten), in video, the white balance function compensates forvariations in the color range of the source lighting. White balanceis accomplished by aiming the camera at a color neutral surface andselecting the white balance function on the camera. The internalelectronics compensate for variations in color. Naturally, it is essentialthat the light illuminating the white card be the same as is in thescene, just as the light on a gray reference card in film must be thesame as is on the scene. This means just the lighting, not any useof color gels for effect. If you are lighting the scene with tungstenlights and plan to use green gels on the lights, you will use a puretungsten light for the color balance. If you color balance with thegreen gels on the lights, the camera will remove the green.Some people use a piece of white paper as a neutral reference, butthis is not reliable. “White” paper can vary widely in color. Morereliable is a standardized photo gray card or a white card made speciallyfor this process. Using a white wall or a piece of paper to whitebalance should be for emergencies only — it is approximate at best.If you are using filters on the camera to alter the color, this mustbe removed for white balance or their effect will be erased by thewhite balance. The white balance can also be used to fool the camera.For example, if you want the overall color balance to be warm intone, you can put a cooling filter (blue) over the lens while doingcolor balance. The circuitry will compensate and when you removethe filter over the lens, the image will then be warm. Special toolsare made for this purpose; the most commonly available are calledwarm cards. These are cards that are slightly blue in varying degreesand thus cause the camera to correct the picture to slightly warm. Anexample of incorrect color balance is shown in Figure 9.43.cinematography164