UFC 4-021-02NF
27 September 2006
change 1, 23 October 2006
4-18.2.4 Avoid backlight. Try to avoid bright areas in the images. Bright images might
become over-exposed (bright white) and objects might appear too dark. This problem
typically occurs when one tries to capture an object in front of a window.
4-18.2.5 Reduce the contrast. A camera adjusts the exposure to obtain good average
light level in the image. A person in front of a white wall tends to appear too dark. If a
gray wall is used instead this problem does not exist.
4-18.2.6 Sensor size. The lens must make an image large enough for the sensor. The
larger the sensor, the more expensive the lens. A lens made for one-half inch will work
for one-half inch, one-third inch, and one-quarter inch sensors, but not for a two-thirds
inch sensor. If a lens made for a smaller sensor is used on a bigger sensor the image
will get black corners.
4-18.2.7 Focal length. Wide-angle lenses have a better depth of field than telephoto
lenses. This means that you can focus both close to the camera as well as at a
distance. Telephoto lenses require a more precise focus adjustment.
4-18.2.8 Iris. Always use auto-iris lenses for outdoor applications, as discussed in the
Outdoor Cameras subsection and indoor applications as discussed in the Indoor
Cameras subsection.
4-18.2.9 Ensure that the monitor viewing area in the Dispatch Center is free from glare
and is ergonomically adjusted for viewing by response personnel.
4-18.2.10 Consider using video quad-processors versus video multiplexers to put
multiple cameras on the same screen. This configuration eliminates choppy
movements.
4-19
CCTV SYSTEMS DESIGN GUIDANCE
4-19.1
Table 4-5 provides additional design guidance and recommendations for
designing CCTV systems.
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