CCTV / Video surveillance
The type of camera impacts the quality of pictures received for
monitoring or recording- therefore, the CCTV camera along with the
lens is an important component of the CCTV system that helps capture
images and convert those to electrical signals which are observed or
To ensure the camera effectively converts light into a video signal,
all cameras require an optical lens to focus the light onto an image
sensor located directly behind the lens inside the camera.
There is a wide variety of cameras and lens available for CCTV
systems which make the task of choosing a system a little difficult.
Here are some purchase considerations that need to be assessed when
purchasing a camera:
- Lighting conditions: Image capture during day and night. The level
of light has a direct impact on the quality of images.
- Position of camera: Indoor or Outdoor. Outdoor camera may require
protective enclosures to resist weather and criminals apart from
aluminum housing and sealed cable entry.
- Field of View: Wide angle or narrow angle- the distance within which
objects are in focus.
- Focal Length: The distance between the camera and the objects to be
- Sensitivity and resolution: Sensitivity means a camera's response to
lighting levels while resolution implies the picture quality or
details in image produced by the camera.
- Colour or monochrome: Certain cameras can also switch between color
and monochrome depending on lighting conditions. Monochrome cameras
are best suitable for low light conditions.
- Price: The price of the camera as compared to the features, benefits
and after-sales service.
CCTV cameras are broadly distinguished by the type of image sensor in
the camera, namely: CMOS (Complementary Metal-Oxide Semiconductor)
image sensor chip and the other more common type known as CCD (Charge
Coupled Device) imaging sensor chip.
The key differences between the two types of image sensors are:
- CMOS cameras are relatively cheaper but do not produce clear images
as CCD cameras do. CCD cameras provide exceptional clarity and high
- The majority of CCTV cameras and video camcorders use a CCD imaging
sensor, whereas CMOS imaging sensors are more commonly used in web
cams, budget home security cameras and digital photography cameras.
The different types of cameras are distinguished on the basis of the
features and benefits offered. Some popular types of cameras include:
- Indoor Dome Camera: Generally used indoors and
provides a variety of configurations such as: standard color,
day/night, and Infrared versions.
- Outdoor Dome Camera: Such cameras have
protective enclosures or weather-resistant, vandal-proof casings
with flexible lens options.
- Box Camera: The box camera can be mounted
or enclosed as desired. The lens is screwed on the front surface of
the camera and provides flexibility in terms of field of view
- Day/ Night Camera: Such cameras switch
digitally or mechanically to suit lighting conditions such that
image quality does not suffer due to change in light levels.
- Infrared Camera: This type of camera
provides infrared illumination in conditions devoid of natural
light. IR cameras have Light Emitting Devices (LED) that
automatically illuminates the field of view to help capture images
in black and white mode.
- PTZ Camera: PTZ is an abbreviation of Pan,
Tilt, Zoom(PTZ) which offers the ability to focus in all directions
and zoom as required.
- Covert or Specialist Camera: Such
cameras are located hidden from the view of the persons being
monitored in the specific camera coverage area.
The images captured by a camera are
effective depending on the type of lens used. The primary function of
the optical lens is to:
- Limit and focus light onto the image sensor of the camera.
- To control the depth of field of the image, either for a wide angle
image or a narrow angle image depending on the distance of the
Auto Iris lens are generally used to
automatically limit and focus light and is also recommended for
varying light and weather conditions. Portable cameras usually have
zoom lens to allow varying points or distances to be monitored
effectively. A CCTV operator controls the zoom lens in a CCTV system.
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