system
Given the following post, respond as if you're commenting on Reddit:
human
Why doesn't my field of view change when my pupils contract/dilate?
gpt
Field of view depends on focal length -- the distance between the lens and the retina (technically the ratio between the size of the retina and the focal length).

The size of the pupil is the aperture size, it only changes how much light enters the eye, just like in a camera.

The reason for this is that the pupil is not a "hole" that you're looking out of. There is a lens that that focuses all the light at one point (provided it's in focus) no matter how large the pupil is. So a narrow pupil is not like "tunnel vision," and a wide one won't increase field of view, because of the lens. All those rays that come in far off-center will get focused on the same point as the center ray.