Camera selection is an important part of your system. It is the eyes into what
is being monitored. There is a camera for just about every situation you can
think of. Let’s start with camera basics. Almost all cameras purchased these
days are digital verses analog. A digital camera focuses light from a lens onto a
computer chip that is sensitive to light. There are two types of chips CMOS
and CCD. CMOS has fewer light receptors than CCD chips. Less expensive
cameras use CMOS chips. High-resolution cameras use CCD chips. All POM
Technologies cameras are CCD cameras.
How important is the resolution?
That depends on what you are using the camera for. If you want to see fine
details such as facial features or images on a cash register display then a CCD
camera is a must. In general expect that a black and white CCD camera will
start at $125 retail including a lens on the CCD camera body. Everything
below that price is likely to be a CMOS-based camera. CMOS chips are used in
low-end products such as web cameras you can attach to your PC. They
provide a good picture for relatively short distances (up to 15 feet) and good
light levels (all interior lights on).
If you are using the cameras for commercial security (like watching for theft)
then a CCD camera is a must.
After resolution the type of lens you use is an important choice. Two important
factors affect how well the lens works; the iris and lens diameter.
Iris
An iris controls the amount of light that passes through the lens opening. Auto-
irises adjust the opening based on changes of light in a room. This is similar to
the human eye. An auto-iris is very important in areas where the lighting
changes such as rooms with exterior windows or rooms with variable lighting.
Lens Diameter
The lens’s opening size (its diameter) affects how wide and long the field of
focus is. Diameter is represented in millimeters (mm). The larger the diameter
the narrow the field but the longer it is. So you want a lens with a low diameter
(such as 2.6 mm) for a room about 40 by 40. But a large diameter (such as 8
mm) would be great for focusing on a distant door.
Low-end cameras come with integrated lenses that have both a fixed iris and a
fixed diameter. Higher-end cameras have separate lenses that must be
purchased or variable lenses.
Digital Security Camera Types
• Black and white security cameras. Inexpensive cameras that
work well in high and low light conditions.
• Color security cameras. Inexpensive cameras that work in
general working light.
• Covert security cameras. These cameras are so small they
cannot be easily seen or are disguised as a different device (such
as smoke detector, clock or teddy bear). They have a short
distance of focus and poorer resolution.
• Day/Night security cameras. These cameras switch from color to
black and white depending on lighting levels. They are ideal for
variable lighting conditions.
• High-resolution security cameras. These cameras have extra
light sensors on their digital chips. They increase the effective
image quality. This type of camera is only effective with high-
resolution monitors.
• Infrared security cameras. These cameras have their own light
source in a light spectrum that can’t be seen by the naked eye.
These cameras are ideal for small areas with no light.
• Outdoor security cameras. These cameras have hardened,
waterproof outer bodies.
• Pan, Tilt, Zoom security cameras. These cameras allow for
remote control of what the camera is pointed at and what it is
focused on.
• Vandal Proof security cameras. These cameras come in
hardened cases that can resist the toughest physical abuse.
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