What determines the field of view?

"The field of view (FOV) of a camera is determined by the focal length of the lens and the size of the image sensor. A shorter focal length gives a wider FOV, while a larger sensor size also increases the FOV."

— Axis Communications Academy, Network Video Fundamentals, 2022

"FOV = 2 × arctan (sensor size / (2 × focal length))."

— Axis Lens Guide White Paper