Ansel Adams founded the zone system, it refers to ways in which “camera obscurer” or a “camera” otherwise seen as a box that allows in light, works. Up till the point a camera would capture images at different settings that were found. However, Ansel Adams found a way in which to capture an image with the correct exposure, this was called the zone system.
The system worked by being split into 10 parts, these were classed as zones. The 10th zone would be the darkest source available in the image while the 1st zone would be the lightest source available. In the middle of this would be the 5th zone, the correct exposure or mid grey. This would be what the photographer would want so to be able to capture a strong image.