CCTV Set up Expertise

Levo have the knowledge and experience to assess a potential installation and recommend the most effective set up both in terms of cost and being able to fulfill the requirements of the brief.

We believe that it is important to firstly listen carefully to what the client wishes to achieve from a CCTV system and may at that stage suggest further benefits that they may not have considered. This then leads to choosing the right cameras and lenses for the proposed installation taking into account key factors like the range needed to be illuminated in complete darkness and the ability to do specific things like read a number plate or recognise a face at a given distance. Sometimes this leads to a conflict because there are basic principles that intervene, so for instance if the client requires a wide angle view from a position yet the ability to read a number plate at 30m then this simply cannot be done with a single fixed lens camera.

An easy approach is to specify vari focal cameras and simply set up the camera on location position by position. This is fine but carries a cost penalty in that the vari focal camera will be almost twice the cost of the fixed lens camera with no difference in picture quality. A preliminary survey of requirements means that we can supply the correct fixed lens cameras at the correct locations thus avoiding the vari focal cost penalty.

Examples of the effect on different lenses on the same camera view using a 1/3" CCD can be seen from the following images .

As you can see it is almost possible to read the distant billboard with the 16mm lens whereas the billboard is only just visible with the 2.8mm lens. If a requirement had been that the details of the billboard at that distance should be able to be clearly read then a lens would have been chosen with a longer focal length still such as 50mm. The other thing of note from the above images is that on the 6mm lens which would be considered a normal view the hedgerow along the front appears straight (as it is in truth) but on the wider angle lenses you can see a curving of the outer edges which gets progressively worse as the angle gets wider.

Another factor as time moves forward is the number of TV lines available from the camera especialy with the significant step from 600TVL to full high definition 1080P. At Levo we will never install a camera with low definition less than 600 TVL as we believe that Customer expectations are growing with the technology and low definitions such as 500 and 420 TVL may have looked great several years ago but are considered poor quality now and rapidly pixelate as you try and digitally zoom with a modern DVR.

Camera Resolution and TV Lines (TVL)

Resolution can be defined as the fineness of detail that can be distinguished in an image. In CCTV cameras, resolution is measured in TV Lines (TVL). A higher number of TVL means that a camera will be able to render images with more detail. However, TVL is not the sole factor that determines the quality of the final output. For example, the resolution does not affect the color reproduction of the camera. The monitoring device and the video processing of the DVR also impact the final output.

This is a hidden benefit of moving on to 1080P in that a wider angle lens may be specified and the definition is then good enough to digitally zoom and obtain the detail required.