System information

MX Cameras
Vicon MX Hardware System Reference 3-7
and corners is lost. MX cameras are fitted with lenses that have an
appropriately sized image circle for the sensor.
If you wish to change the supplied lens, you must consider the sensor
size of the new lens. Even if the focal length of the new lens is the
same, a different sensor size will produce a different field of view. For
example, the sensor sizes of C-Mount lenses are specified in formats
of 1”, 2/3”, 1/2”, 1/3”, and 1/4”, which reflect a ratio of
1:0.69:0.5:0.38:0.25. Thus, a 1/2” format is 50% of a 1" format, a
1/3” format is 75% of a 1/2” format, and so on. For guidance on the
necessary image circle diameter for a specific sensor format, see
details on the MX camera lens specifications in Appendix D Technical
Specifications.
Table 3-2 gives the formulae used to calculate the angle of view (AOV)
and field of view (FOV) for camera and lens combinations. These
formulae require the dimensions of the sensor area used for each of
the MX cameras at different frequencies.
where:
f = focal length of the lens (mm)
h = horizontal width of sensor (mm) (see
Sensor size entry in
Table 3-1 on page 3-2)
v = vertical height of sensor (mm) (see
Sensor size entry in
Table 3-1 on page 3-2)
L = distance from the lens to the object (m)
As an example, consider an MX40+ camera with a 20 mm lens
operating at 160 Hz at a distance of 9 m from the target markers:
• Horizontal AOV would be:
2 x Tan
-1
(16.5/40) = 44.8 °
• Vertical AOV would be:
2 x Tan
-1
(12.1/40) = 33.7 °
Table 3-2: AOV and FOV formulae
Horizontal
AOV (°)
Vertical
AOV (°)
Horizontal
FOV
Width H (m)
Vertical
FOV
Height V (m)
2 x Tan
-1
(h/2f) 2 x Tan
-1
(v/2f)
h x L/f v x L/f
MXhardware_Reference.book Page 7 Thursday, September 7, 2006 11:36 AM