Cinematography-Theory-And-Practice

“blinding white,” and so on. We need more precise descriptions,especially if we are tying to communicate exposure concepts toother people. Fortunately, a great still photographer named AnselAdams developed a method of dealing with exposure in a more scientificand precise manner called the Zone System.will call the most completely black section Zone 0 and each tone thatis one f/stop lighter is one zone “higher.” For example, a subject areathat reflects three stops more light than the darkest area in the sceneare all relative. Zone 0 is not some predetermined number of footcandles— it is the darkest area in this scene.Still photographers might be accustomed to thinking of ten zonesin all, but if there is a great contrast range in the scene, there mightwell be zones XII, XIII, or more. (Zone system purists will no doubtobject to such an extreme simplification of the method, but it is sufficientfor the present discussion, since few cinematographers dotheir own darkroom work.) What we are measuring is subject brightness(luminance), which can vary in two ways: the inherent reflectanceof the different parts of the subject matter and the amount of lightthat falls on it. Reflectance is a property of the material itself. Blackvelvet reflects about 2% of the light that falls on it. A very shinysurface can reflect up to 98% of the light. This is a brightness ratioof 1:48. This is what makes a material dark or light — how reflectiveit is.However, this is the reflectance ratio if the same amount of light fallson both objects. In reality, different amounts of light fall on differentareas in the same frame (indeed, we make our living making surethey do, as we manipulate the lighting of a scene). In natural lightsituations the reflectance ratio can be as much as 3200:1. Picture anextreme example: a piece of black velvet in deep shadow in the samescene with a white rock in the sun.The brightness range of a typical outdoor subject is about 1000:1.This is 15 stops and here’s the rub: imaging systems cannot reproducethis range of subject brightness, just as the human eye cannotaccommodate such a range.Figure 10.30. A silhouette shot isdone by properly exposing for thebackground and not lighting theforeground, as in this frame fromNine and 1/2 Weeks, shot by PeterBiziou.exposure201