DSLR Cinema, 2nd Edition

Appendix 3

Exposure and Dynamic Range

Technically, video exposure works differently than film exposure. Aside from the obvious chemical properties of film that allow for the emulsion process, film has a smooth “characteristic curve,” whereas video has a sharp curve, leading to sudden drop-offs on the curve and toe (see Figure A3.1). The characteristic curve is simply the amount of chemical density on the film activated based on the intensity of light. This density can be plotted on a graph as a relatively straight line with a curve on the top (shoulder) and bottom (toe). The slope of this curve is called the gamma, and it essentially determines the contrast of the scene. Changing the gamma curve changes the contrast value of the shot. You can ...