Cinematography-Theory-And-Practice

Given the fact that providing tungsten light is costly, while sunlightis usually far more abundant, most motion picture films are type B,balanced for tungsten. The idea is that we put a correcting filter onwhen we can most afford to lose light to a filter factor — in theavailable for which no correcting filter is needed in daylight or HMIsituations. They come in ISOs up to 250, which can be extremelythe end of the day it gets dark surprisingly fast; this applies both toexteriors and interiors that are partially or fully lit with daylight.There are four basic reasons to change the color of light at thesource: to correct the color of the lights to match the film type(instead of using a camera filter), to match different types of lightingtionslike greenscreen or bluescreen.To shoot with type B film under daylight balancearea) an 85 orange filter is used (Figure 13.22). The 80A or 80B bluefilters for shooting daylight film with warm light are rarely used,daylight and HMIs. There is some light loss when using a correctionfilter, and the filter factor must be used to adjust the T/stop. For convenience,most manufacturers list an adjusted Exposure Index (or ISO/ASA), which allows for the filter loss; this will appear on the film canand in data sheets for that film stock.Another form of filter that is sometimes used is a UV or haze filter.Skylight contains a great deal of ultraviolet radiation that can causethe image to go slightly blue. This is especially true at high altitudes-be listed on cans of black-and-white film. This is not related to correctionfilters, since none are needed. It is because black-and-whitefilms vary in their sensitivity to colors. In most cases the ASA fortungsten light will be 1/3 stop lower. Very important: when usingthis adjusted EI, do not also use the filter factor. Smaller color mismatchescan also be corrected with color filters, as well. If the scenegenerally used in film and video production are discussed in the nextsection. Filter families are shown in Tables 13.1 through 13.34.Conversion FiltersConversion filters work with the blue and orange ranges of the spectrumand deal with fundamental color balance in relation to the colorspectrum for smooth color rendition. (LB) Light Balancing filters arewarming and cooling filters; they work on the entire SED (SpectralEnergy Distribution) as with the conversion filters, but they are used tomake smaller shifts in the Blue-Orange axis.Camera Lens Filters for Color CorrectionColor compensating filters (CC) are manufactured in the primary andsecondary colors. They are used to make corrections in a specific areaof the spectrum or for special effects. They affect only their ownnarrow band of the SED. Don’t make the mistake of trying to cor-band of the spectrum and correct only one wavelength.image control261