Optical reasons, aka depth of field. Exceptionally well explained in Cameras and Lenses – Bartosz Ciechanowski https://ciechanow.ski/cameras-and-lenses/ https:

Optical reasons, aka depth of field. Exceptionally well explained in Cameras and Lenses – Bartosz Ciechanowski https://ciechanow.ski/cameras-and-lenses/ https://ciechanow.ski/cameras-and-lenses/ Depth of field - Wikipedia https://en.wikipedia.org/wiki/Depth_of_field https://en.wikipedia.org/wiki/Depth_of_field