I am going to set the blender camera as the real surveillance camera, which the focal lens and fov of real camera is 4mm and 69.9 degree.
Firstly, I manually set the focal len of blender to 4mm, the blender automatically set the fov to 140.53 in the perspective view, I changed the sensor width and height, it has the influence but still doesn't simulate the focal len and fov as the real camera I used.
Secondly I followed this post - How to simulate a real camera with blender, but in the panoramic view, I added a new camera, even the parameters (focal len, fov and sensor width height) are changed as shown the post, nothing happens.
I wondered why in the perspective view both focal len and fov are automatically changed? and why the change in the panoramic view doesn't change at all.
The blender version I am using is 2.7.9
This is the picture of focal len at 4mm below
This is the picture of focal len at 12mm below
Increasing the focal len will make the objects in far distance look bigger?