system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how do bugs eyes work….specifically flies and dragonflies. Like what do they actually see and how does it work?
gpt
They have "compound eyes." Their eyes are made up of thousands of tiny lenses. The simplest way to explain how they see is each lens is a tiny portion of a larger picture sort of how many pixels make up an image on a screen. This way the insect has a very wide range of vision. 

The downside to insect compound eyes is that they can't control how much light enters their eyes, humans have pupils that can control how much light to let in. That means insects are extremely near-sighted. On average, they can only see a few yards away. 

The upside to compound eyes is that it's extremely good for differentiating movement. They can react to movement much more quickly.