This phrase comes from long ago when people believed that the eye's pupil was solid and shaped like an apple.

这个短语很久之前就有了，那时人们相信瞳孔是立体的、形状像苹果一样。

If a lot of light is coming in like when using light modes, eye pupils contract allowing less light in, creating a wide depth of field.

如果像使用灯光模式时一样有大量光线进入，眼睛瞳孔会收缩，允许较少的光线进入，从而产生宽广的景深。