system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are camera lenses round if photographs are rectangular?
gpt
Pobody is right, this owes much to the way glass lenses are ground into their convex shape. Also, the image is subject to aberration at the edges of a lens, and if a round, convex lens is used to focus the image, one can achieve a wide field of view that will fill the square frame, leaving the distorted edges off of the film.