"A longer focal length (such as 48 mm) results in a shorter depth of field compared to shorter focal lengths, meaning only a narrow range of distances will be in focus."
- Axis Communications Academy, Network Video Fundamentals, 2022
"Depth of field decreases as the focal length increases."
- Axis Lens Guide White Paper
References:
Axis Communications Academy, Network Video Fundamentals, 2022 (p. 22)
Axis Lens Guide White Paper