when i was lying in the grass in spain one day, i started thinking about depth of sharpness/field.
you know - low f-number >> very unsharp background, high f-number >> sharper background.
since a low f-number stands for a wide aperture (and so on), this basic optical correlation must also apply to the human eye - with the iris as a “biological aperture”.
if so, our range of vision would look like this, depending on how much light is available:
