The camera is the director of photography’s dominion. To accept that responsibility is to become a master photographer. Cinematographers work at the intersection of art and physics—understanding light, color, optics, filtration, and exposure well enough to make deliberate creative choices under pressure. A solid photographic foundation isn’t optional; it’s the starting point.
At its core, exposure in cinematography is no different than exposure in still photography. It relies on three values: the sensitivity of the recording medium (ISO), the shutter speed (frame rate), and the intensity of light. Of these, the DP controls two. ISO and frame rate are set first on the camera and then mirrored on the light meter. Once those values are locked, the meter measures light intensity and produces an f-stop—an aperture value inside the lens that regulates how much light reaches the sensor.
Think of the meter as a clone of the camera. If the ISO or shutter speed on the meter doesn’t match the camera, the exposure reading will be wrong. Most modern meters account for frame rate directly; older meters require a fractional shutter-speed equivalent. At 24 frames per second with a standard 180-degree shutter, that equivalent is 1/48 of a second. Change the frame rate or shutter angle, and the exposure changes with it.
Shutter speed is more than math—it defines motion. The 24-fps standard, adopted in 1927, produces motion blur that we now associate with the “film look.” Push frame rates higher for slow motion, and you shorten exposure time, requiring more light. Shoot faster, and exposure demands rise. These tradeoffs are constant on set, and understanding them allows the DP to adapt without compromising intent.
ISO, whether referring to film or digital sensors, describes sensitivity to light. Early photographic emulsions were painfully slow, requiring long exposures and bright daylight. Today’s digital sensors are extraordinarily fast, enabling naturalistic low-light cinematography with smaller fixtures, practical sources, and even candlelight. Faster sensors haven’t just improved image quality—they’ve reshaped how films are lit and who can afford to light them.
Once ISO and shutter speed are set, exposure becomes a question of aperture. F-numbers describe the size of the lens opening, and each full stop represents a doubling or halving of light. DPs constantly compensate: for changing frame rates, filters, lighting conditions, or creative intent. Aperture rings on cinema lenses are smooth, not clicked, because precision lives between the numbers.
Exposure is never purely technical. Most cinematographers underexpose highlights to protect detail, or slightly overexpose shadows to reduce noise. These choices are interpretive, shaped by experience and taste.
Depth of field, shutter angle, and exposure are inseparable. Control one, and the others respond. Mastery comes from understanding these relationships well enough that decisions feel instinctive, not reactive.
This book begins here because everything else in cinematography depends on it. Exposure is the grammar of the image. Learn it deeply, and the camera becomes an expressive tool—not a guessing machine.