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How to Choose a Closed-Circuit TV System for Your
Home
To supplement your home security system, you may
want to consider including a closed-circuit
television system (CCTV). Such a system includes a
surveillance camera or cameras, lenses specially
selected to watch particular areas of the home, and
a videocassette recorder that records what the
camera or cameras see.
CCTV Conduct Preliminary Research
Steps:
1. Survey your home. Determine which areas you might
want to monitor via CCTV. Some areas outside the
home might include the garage, backyard, an adjacent
alley, or outside a gate or fence.
2. Decide if you want to put more than one camera
inside your home. You may, for example, want to
monitor how a nanny watches your child during the
day.
3. Decide on the size of the scene you wish the CCTV
system to observe. This will determine the size and
type of camera and its lens.
4. Decide on the camera format. There are five
choices: 1-inch, 2/3-inch, 1/2-inch, 1/3-inch or
1/4-inch. It is most cost effective to select
1/2-inch, 1/3-inch or 1/4-inch, because those
cameras can use the widest range of lenses.
5. Determine what type of lens you wish to use.
There are four types of lenses for CCTV use: fixed
aperture, manual iris, auto iris and zoom. If the
area you wish to observe experiences infrequent
changes in light, use a manual iris lens, which can
be adjusted for light only by hand. If the area the
CCTV system will be observing experiences frequent
changes in light, use an auto-iris lens. These
lenses adjust to light changes automatically.
Auto-iris lenses come in Video or DC, and cameras
generally support one format or the other. Be sure
your lens matches the camera. To perform closeups,
get a zoom lens. Motorized zoom lenses are
available.
6. Based on the camera format you chose (1-inch,
1/2-inch, etc.), choose the lens format.
7. Ascertain how many cameras you will need. This
will determine whether you will need a switcher, a
multiplexer or multiple monitors.
8. Determine the monitor size. The larger the
monitor, the bigger the object will appear.
Available sizes include 9-inch, 12-inch and 17-inch.
9. Decide if you will have to show more than one
scene at a time on one monitor. If so, you will need
to include a quad switch that allows up to four
cameras to be viewed simultaneously on one screen.
10. If you plan to record more than 4 to 6 hours,
you will need a commercial grade recorder.
Otherwise, you can use a standard VCR.
11. Determine if you want to record all cameras at
once in full screen mode if you intend to use a
multicamera CCTV system. If you want full screen
recording of all cameras, you will need to include a
multiplexer.
12. Use a measurement wheel or slide chart to
determine the focal length, or the distance from the
camera to the subject, and the height or width of
the subject in the usable picture.
13. Write down all of the information you gathered
doing these steps.
Tips:
One of the most popular lenses in use today is the
Vari-Focal lens, because it's adjustable.
Manufacturers or suppliers of lenses have
measurement wheels or slide charts that can figure
out a missing variable as long as the other two
variables are known. There are also charts to assist
you in determining what size lens would be required
to view a certain size scene.
Choosing the CCTV Components
Steps:
1. Confer with a home security advisor.
2. Discuss your preliminary research findings with
the consultant and select components.
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