System information

MX Cameras
3-8 Vicon MX Hardware System Reference
• Horizontal FOV at 9m would be:
16.5 x (9/20) = 7.43 m
• Vertical FOV at 9m would be:
12.1 x (9/20) = 5.44 m
Important
These formulae take into account only the optical components of the camera
and lens, thus they calculate the maximum possible theoretical Field of View
from this combination. Poor illumination of the volume by camera strobes,
less than optimal aperture or gain settings, or poor marker surface quality
might all reduce the FOV in which a camera can recognize a marker below
this maximum theoretical level.
Please note when using these formulae that frequencies above the full-
resolution frequencies given in Table 3-1 on page 3-2, the sensor area is
reduced due to vertical windowing, as described in Field of View on page 3-4.
Aperture and Depth of Field
Another significant factor in choosing a lens type is the aperture (also
known as the f-stop value, f-number, and F#), which refers to the
speed with which the lens can pass light in a given time.
The aperture is the ratio of the focal length of the lens to the diameter
of the lens opening, which determines the amount of light that can
pass through the lens in a given time. Smaller f-stop values (e.g. f2,
f2.8) represent wider apertures that allow more light to pass through,
while larger f-stop values (e.g. f11, f16, f22) represent narrower
apertures that allow less light to pass through. Typically, faster lenses
have larger diameter optics that can pass more light.
Each f-stop value changes the lens opening from the next f-stop by
a factor of 2. For example, decreasing the aperture from f11 to f8
allows twice as much light to pass through. Increasing the aperture
from f11 to f16 allows half as much light to pass through.
The aperture and magnification affect the depth of field, that is, the
portion of the image that has sharp focus. Immediately surrounding
this area, there is a region in which the image remains in focus.
Outside of this area, moving towards or away from the lens, the focus
becomes progressively less sharp and the image appears out of focus.
Thus, as the aperture and focal length decrease, the depth of field
increases. Conversely, as the aperture and focal length increase, the
depth of field decreases.
MXhardware_Reference.book Page 8 Thursday, September 7, 2006 11:36 AM