Focal length

You can set the camera's focal length here – instead of the viewing angle. The focal length is equivalent to the lens on a small camera (20mm = very wide angle, 135 mm = small telephoto lens). The default of 50 mm is equivalent to a normal lens.

Note: The Viewing angle and Focal length parameters are mutually dependent. Changing the viewing angle of the camera will cause the focal length to change and vice versa.
The viewing angle is measured diagonally.
Viewing angle, Focal length and diagonal are mutually dependent:

tan (camera angle / 2) = (diagonal / 2) / focal length

1 Diagonal (43.3 mm, for example)
2 Focal length
3 Viewing angle

Viewing angle

Use this to set the camera's viewing angle (47 degrees is the default) – instead of the focal length. If you require a wide-angle view, set a higher value. If you require a more close-up view, enter a lower value.

Note: The Viewing angle and Focal length parameters are mutually dependent. Changing the viewing angle of the camera will cause the focal length to change and vice versa.
The viewing angle is measured diagonally.
Viewing angle, Focal length and diagonal are mutually dependent:

tan (camera angle / 2) = (diagonal / 2) / focal length

1 Diagonal (43.3 mm, for example)
2 Focal length
3 Viewing angle