How to assess the reliability of your video Surveillance System?

security CCTV camera or surveillance system with young man on blurry background

Your video surveillance system is designed to protect you for as long as possible in a reliable and constant manner. It operates 24 hours a day and offers you total and very effective monitoring. However, it is subject to risks such as the weather, malice or vandalism, or simply clumsiness. Many homes or stores find themselves out of protection because of a malfunction due to a disruption of your video surveillance system by an outside agent. Here is what you need to pay attention to when purchasing a CCTV system, so that it works best, even in the event of a disruption.

Table of Contents

Obstruction detection

Some cameras are equipped with functions that allow them to detect when their view is blocked. Whether by dirt, because of a deliberate breakage of the lens or because of an obstruction of the optics made by a burglar, your alerted camera will in turn alert you of its inability to function properly.

A secondary energy source

Your cameras must have a second power source that will allow them to continue operating even in the event of a power failure. Whether in the form of batteries or batteries, this detail is very important because burglars often cut the power supply to homes before burglarizing them, or cut the wires supplying the cameras which will hinder them in their businesses.

 An independent transmission system

In the event of a power failure, your internet connection is interrupted. Your cameras must therefore have another means of sharing their data. If they are equipped with a GSM or GPRS system, they will communicate via the mobile telephone network, while if they are equipped with a PSTN system, it will be by the fixed line of your home or your store that they will exchange the data.

Which camera to film at night?

The surveillance of your home or your store must obviously be spread 24 hours a day, without interruption. Occurring at any time, burglaries allow no time when your video surveillance does not work or works less efficiently. The quality of the images rendered by your cameras at night must therefore be an important factor when choosing a protection system. You have the choice between cameras with built-in lights that illuminate the area they are monitoring, and night vision cameras that will capture sharp images without the need for light.

Some cameras are designed to detect a change in the nature of brightness, and therefore to detect at night. In night mode, they then start to work differently and provide very sharp black and white images.


Other cameras have LEDs  whose role is to illuminate the area to be filmed when the brightness is too low. Some have sensors that vary the intensity of the LEDs depending on the light. These cameras have the disadvantage of being inconspicuous and of attracting attention. You should also make sure that the LEDs light up at the right distance, and that the area filmed in broad daylight will be close enough to make images lit up enough at night.

The tube cameras are generally more efficient than the dome cameras in terms of night vision . Dome cameras are designed to be discreet and solid, protected by glass cases. They are therefore subject to space constraints. Tube cameras are freer and evolve in a housing that allows more electronics. Their night vision therefore sometimes extends up to 100m while the night vision of dome cameras rarely exceeds 50m.

How to choose your focal lengths?

The focal length of your video surveillance security cameras is one of the main elements of your protection system. Indeed, it is she who will determine what you really see, the image returned to you and therefore the area covered by your protection. This focal length will allow you to obtain more or less wide or more or less targeted images, and therefore to adapt your surveillance to a room, a need or a danger. Quite technical, the focal lengths must be known by an owner wishing to protect his home or his store. Choosing this part is almost as important as choosing the type of camera you will install. Here are the focal lengths and the sizes of the areas they will monitor.

  1. The 2.1 mm focal lengths film a scene from 14 m to 6 m away.
  2. The 2.8 mm focal lengths film a scene from 14 m to 8 m away.
  3. The 3.6 mm focal lengths film a scene from 14 m to 10 m away.
  4. The 6mm focal lengths film a scene from 14m to 20m away.
  5. The 12mm focal lengths film a scene from 10m to 25m away.

Fixed focus camera lenses

The values ‚Äč‚Äčexpressed above show that the size of the filmed area becomes smaller as it is further away from the camera. These areas, filmed by large focal lengths, must be very carefully chosen and targeted. Cameras that have them must be installed with care since they will not allow you to see what is happening in their immediate environment. Cameras equipped with small focal lengths will film a large area in which you will be sure to detect everything that is going on. The quality of your images will however deteriorate if you have to zoom in when using the images after a possible intrusion.

Video surveillance: which regulations?

An often overlooked chapter in video surveillance is that of the regulations governing this increasingly common practice. Having become essential and in the case of stores, inevitable, video surveillance is sometimes trivialized to the detriment of the laws associated with it. Compliance with the regulatory framework in which your protection will evolve is however not only important so that it is not removed at the slightest complaint from a customer or a passerby, but above all so that the images you remove from it are usable in the event of burglary, theft or theft.

 Declare your video surveillance system

 Your video surveillance system must be accompanied by a declaration to the CNIL, including the reasons for this installation, its description and the type of recording of the images shot. Thus, even a private video surveillance system comprising a small number of cameras and used only for the surveillance of personal property, must be declared to function legally. Individuals must also ensure that their video surveillance systems do not film the public highway or the street. It is imperative to contain surveillance on your property. Any camera filming the public route will have to be declared at the prefecture.

 Beware of surveillance of places welcoming the public

 As for places welcoming the public (shops, parks, pharmacies, etc.), the law requires you to declare your video surveillance system to the prefecture. Attach to this declaration a CERFA document specifying the installation points of your cameras, their roles, and the signage you have chosen to use. This declaration will be renewed according to the rules of each prefecture.

 Don’t keep your images too long

The images of the public or the public road that you film can only be kept for a certain period of time. This varies between 7 and 30 days depending on the prefectures. So be sure to inform yourself when installing your video surveillance system.