5 Common mistakes in CCTV


It is falsely believed that a CCTV system can replace an alarm system. There are many cases where it is mentioned that a video system is better, because it can replace several sensors, with digital motion detection.

Although that might be the idea in some years, once the video analysis and intelligence software matures; For now it is NOT a good replacement. Motion detection in a CCTV system fulfills the function of making the recording task more efficient, but it is not its intention to play the role of traditional sensors.

The true role of a video system is the VERIFICATION and RECORD of the events that have occurred and detected by traditional alarm systems. In this way when a sensor detects and the alarm panel warns, the man in charge must use the video system to verify what happened and react in a timely manner, without exposing its integrity. Additionally a CCTV system is excellent for deterrent effects.


In addition to knowing the format (size of the CCD), resolution (vertical and horizontal lines), sensitivity (ability to general useful video signals, in low lighting), type of power and possibility of camera color, features should be investigated for specific applications, such as Manual White Adjustment Control (WBC), when there are multiple types of lighting; or WDR (A Backlight Compensation circuit, of better quality than the typical BLC); The camera must have the ability to handle auto-controlled lenses directly or by video (DC / VD); It is important to know the “Phase” setting when the cameras are AC power and also make the proper adjustment of the iris, with the “Level” potentiometer. Finally it is key to verify the level of gamma, as well as the level of the signal to noise ratio, the operating temperature and relative humidity.

When the camera does not use auto-iris lenses, it is essential that it has a high-speed shuter or ESC compensation circuit. Important to know the differences between CCD, CMOS, SIMD and the new HD or high resolution. In all these little details and acronyms, sometimes confusing and meaningless, are the big differences in each camera.


Nowadays the sensitivity of the cctv security cameras has improved a lot, that is, they can easily see very low light levels. However, many manufacturers take advantage of other functions such as the ability to see infrared light and then it is very common to say that the camera sees 0 Lux. Actually, he is seeing with good light, generated by the infrared spotlights, only that for the human it is darkness.

Here we find several types of cameras:
Those that are in color and when the crown of IR light is turned on, they continue to see in color, only that the IR light when reflected is observed in the image in a monochromatic way.

Those who perform a video analysis and when the lighting is so low, they decide to change the operation of the video processor and really change color to black and white, freeing the processor from identifying and generating colors, and therefore increasing its resolution and sensitivity , in monochrome mode. This feature is very popular in places where darkness is really an inevitable company. The latter are, of course, more expensive and of better quality. Even some may also have IR LED’s crown or not.

That mechanically remove an IR light filter that allows you to modify its sensitivity and resolution characteristics. The vast majority of cameras called “Day / Night”, are of type a), only a few of excellent quality and high price belong to group b) or c). So please look very well what you are buying.


The vast majority of installations use the standard lenses of the market (which are the most economical) and / or those that come with the camera from the factory. However, in many occasions very large areas are seen where the detail is lost and in others details are seen but coverage sites are lost.

I have always said that nobody invests a large sum of money in a CCTV system, to detect that it was stolen by “someone, who seems to be a human.” The idea of ​​a video surveillance system is to determine exactly, what is the identification of the intruder, or thief and that perfect evidence of the incident occurred is recorded. Otherwise we are throwing money …

The proper combination of the camera format and the calculation of the focal length of the lens allows the field of vision obtained to be the desired one. To do this we must measure the distance from the camera to the oA suitable combination of the camera format and the calculation of the focal length of the lens allows the field of vision obtained to be the desired one. For this we must measure the distance from the camera to the object I want to see, and additionally take the horizontal and vertical measurements of the object. With these parameters and knowing the camera format, I can easily obtain the focal length of the lens expressed in millimeters. This way I guarantee that in each site, I see exactly what I want, neither more nor less.

When the calculated lens does not exist exactly on the market, it is good to use manual varifocal lenses, which allow me some tolerance and variation. However I MUST calculate the varifocal lens and not be content with the traditional varifocal (3.5 to 8 mm), which in many cases fall short or long to the real needs.

I recommend using the calculators, which each brand of lenses has available on the Internet, or more practical and professional to learn how to use the table (round and slide) that many manufacturers give at trade shows and safety shows. Another alternative is to do the calculations using the simple mathematical formulas (any basic CCTV course, teaches them), when you have all the data and finally use a real measuring lens (spyglass type) with which you can easily observe the scene and Know the relevant focal length.

Subsequently, I must take into account the F-Stop or maximum aperture of the Iris to be used, verify if the type of Autoiris (DC / Video) lens that my camera can handle and in case of using cameras with an IR crown, demand a lens that sees both types of light clearly.


We never design, install, sell and / or quote these items, because the cost of the system is greatly increased.

The mistake is that not taking them into account the budgets always fail and in the end it is the same end user who cries out, making us look ridiculous, because we look like beginners … has it happened to them? When we use cameras outdoors, there are many accessories that are used to ensure the proper functioning of the image capture unit. The covers and supports are the main and most common.

In this regard there are formulas to know which is the best cover and the length of the support. There are IP (International Protection) or NEMA tables, to know the degree of protection needed. However, the only thing I can recommend in this article is that we DO NOT replace them with the elements that are manufactured locally with Creole technology and misused. The material, shape and type of finish of covers and supports, is essential to give a long life to electronic equipment. Accessories such as glass cleaner, heater, fan, rheostat, pressurization and thermal insulation cover, are indispensable when the cameras are under the elements of the sun and rain. Long-range IR bulbs, signal encoders, transceivers for transmission medium change, adequate ground and excellent electrical energy from a UPS; They are an excellent complement for everything to work as expected.