Choosing Security Cameras, What Are The Options?

Whatever your requirement, there is a security camera with features to solve your particular issue.

Detailed below are the features and specifications for security cameras you need to think about before purchasing a CCTV system.

Security Cameras Come In Many Shapes and Sizes

It is one of the few areas where you can choose a camera on personal preference. Unless you need a very specific security camera for a special need which requires a particular body shape to house the lens and electronics, most lens/features can be found in a variety of styles.

Below are some examples. They can broadly be classed as Bullet or Dome styles.

Choosing security cameras that suit your requiremnts is extremely important.

Camera Lenses and Focal Lengths

Focal length is measured in millimeters (mm). It gives a good indication of the camera's field of view or viewing angle. Shown below are three examples of focal length lens sizes. What it shows is a smaller lens will show a wider area but with less detail.

Examples of focal length lens sizes

Irrespective of styles, there are two types of camera lens available. Those with fixed focal length lens of say 3.6mm, 6mm, 12mm etc which tend to be cheaper and are good for smaller areas or specific purposes, and variable focus security cameras which allows you to adjust the focus of the lens between say 2.8mm and 12mm or 4mm and 9mm.

This allows the installer to capture only the picture required. The more a camera can be zoomed in the more detail it will capture. And of course if circumstances change in the future or the camera is moved, they can be readjusted to suit the new position.

Day/Night Infra Red Security Cameras

In a security camera's specifications you will find the level of light a camera can work at. It is referred to as the camera's lux level. The lower the lux level the better the security camera can see in low light situations.

Infra red cameras usually have a zero lux level because they have a series of Infra red LEDS which switch on automatically when the light level gets too low - somewhere around 20 lux. The security cameras record in colour during the day and switch to black and white at night.

The distance the camera can see depends on the number and size of the LEDS. It doesn't pay to believe the manufacturer's specifications regarding the distance, in real world situations we tend to halve their claims.

IR cut filters

Many Infra Red day/night security cameras struggle to give good real life colour pictures because of the technology required to process the IR at night. They can appear a little 'washed out' during the day. An innovation that has overcome this problem is mechanical IR cut filters.

The filter is divided into a red and a green side and moves the correct colour behind the lens depending on whether it is viewing daylight or night. It stops the camera receiving IR light during the day and makes the colour more normal to human eyes.

Colour at Night

Something coming on to the scene are cameras whose LEDS give colour pictures at night. These are tending to be high end cameras and their prices reflect that. More about these security cameras later.

Security Camera Resolutions

The information on DVRs showed you the resolutions they can record at. You would have seen that, if the budget allows, you want all channels to be recording at DI (720X576 pixels). You then need cameras that produce a D1 size picture to record.

The table below shows different security camera resolutions from our supplier. TVL is defined as the maximum number of alternating light and dark vertical lines that can be identified per picture height. A resolution of 400 TVL means that 200 distinct dark vertical lines and 200 distinct white vertical lines can be counted over a horizontal span equal to the height of the picture. The more lines that can be viewed the clearer the picture.

700TVL 976 X 582 pixels
540TVL 752 X 582 pixels
420TVL 500 X 582 pixels

As you can see a 540TVL camera has more than enough pixels to record a D1 picture whereas a 420TVL security camera does not.

A 700TVL camera could be considered a waste of money because it is producing a picture bigger than a DVR can record because the DVR chops off the edges of the picture it can't handle.

Having said that there are 960H DVRS which can record the full picture, which is 34% wider than the D1 picture. These cameras are often used with Hybrid DVRs which can record both 960H analogue and High Definition IP security cameras.

Wide Dynamic Range

A useful feature for some areas with difficult lighting conditions is Wide Dynamic Range (WDR). A common situation is where a camera is looking at a door way. The light outside is very bright, and when someone walks through the doorway all you see is a dark silhouette.

The WDR camera copes with this backlight and allows more detail to be seen.

Specialty Security Cameras

Number Plate cameras - As the name implies these are specifically designed to pick up number plates in less than ideal conditions.

Face recognition security cameras - These cameras zoom in on the face as they come into range.

Pan Tilt Zoom cameras - These security cameras can pan and tilt and zoom by either a control panel or through your DVR.

There are others with auto tracking capabilities. When they detect movement they zoom in on the cause and track it until it is out of range.

IP- (Internet Protocol) security cameras. These can be stand alone single cameras which you can view through the internet or smartphone. They can have SD card storage which records events such as motion detect.

To have continuous recording they need to be connected to a NVR (Network Video Recorder) or NAS (Network Attached Storage). Multiple security cameras can be combined with an NVR to create a High Definition CCTV system.

Taxi security cameras

From Jan 2000 to Feb 2010 there were 677 recorded assaults against taxi drivers. This resulted in the requirement for taxi cameras to be fitted to all taxis by 1 August 2011.

Contact us to discuss your requirements before choosing security cameras and take advantage of our free assessment and assistance.

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