Short · Cameras
How does your phone camera focus?
Light from each point meets again at one spot. If that spot lands on the sensor the point is sharp, and a motor moving the lens less than a millimeter makes it so.
Try it yourself
Opens Focus Lab. Change the same thing yourself.
Transcript
How does your phone camera focus? Light from each point of the scene bends through the lens and meets again at one spot. If that spot lands on the sensor, the point is sharp. If not, it smears into a blurry disc. Now bring the flower closer. Its light meets farther behind the lens, so a tiny motor pushes the lens forward, less than a millimeter. Too close, and the lens runs out of travel. That's the minimum focus distance. Follow to see how the world works.