system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are pictures rectangles when camera lenses are round?
gpt
* Lenses are round because it's easier to make them that way and rectangular lenses cause weird problems.

* Pictures are rectangular because it was easier to make film rectangular and it also matches humans' natural field of view better than a circle would.

* Digital camera sensors are rectangular because we are already used to photos shaped that way.