system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is camera exposure and why does it make picture look so good?
gpt
The exposure is the amount of light that hits the picture-making part of the camera. Good exposure is important because cameras are not as good at seeing really bright things and really dark things at the same time as people are. Really bright things go totally white and dark things go totally black, like when you walk out of a dark room and into the sun. To allow you to see, your eye responds by closing down its iris to let less light in. A camera performs in a similar way by closing down a metal iris. The hole the iris allows is called the aperture and its size is measured in "stops," which are a ratio of the size of the opening to the focal length (zoom-in-ed-ness) of the lens.