Chrome Ball and Grey Ball Compared

A chrome ball records the environment, a grey ball records how that environment exposes. Why VFX crews shoot both and what 18 percent reflectivity means.

The chrome ball records direction

The mirror surface shows where the light comes from, how many sources there are and what surrounds the subject.

The grey ball records level

The grey surface uses 50% grey paint with 18% reflectivity. It shows how bright that light actually is and how it falls off around the sphere.

Why a sphere beats a card

A grey card faces one direction. A sphere shows light arriving from every direction at once, including from behind the subject.

Buying both or buying a split ball

A half mirror half grey ball carries both surfaces on one sphere and saves weight. Two separate spheres give a full hemisphere of each, which reads better on large sets.