How to choose a CCTV camera

Connection: analogue or digital

With the current level of technology development, the difference between the image of an analogue and digital IP device will be completely invisible to the user when it comes to cameras with resolutions up to Full HD inclusive (2MP, 1920x1080). Larger resolutions are currently only available for IP cameras.

The only fundamental difference between analogue CCTV cameras is that they require a compatible DVR to work. Whereas the IP camera is able to work autonomously. However, in essence, the analogue modern video surveillance system is only in the area from the camera to the DVR. Anything further is a number.

Sometimes analogue cameras refuse to work with other DVRs manufacturers, resulting in additional costs

If we are talking about modern analogue cameras with HD and Full HD image quality (and buying very old cameras with D1 or 960H quality is just throwing money away), then there is a danger of incompatibility. The incompatibility of analogue video equipment, which is very similar in characteristics, confuses end users and complicates the construction of video surveillance systems for integrators. Often, cameras purchased by people simply refuse to work with DVRs from other manufacturers, which leads to additional unjustified expenses of money, time and nerves. Remember - you can avoid incompatibility problems for analogue cameras in 99.9% of cases if:

- buy only AHD cameras for an AHD standard DVR (if you buy a 2 Mp AHD camera for a 1-megapixel DVR, make sure that the latter supports 1080N mode, otherwise it will not work);

- buy only HDTVI cameras for Turbo HD DVR (when buying a 2 MP HDTVI camera, make sure that the DVR supports it);

— buy only HDCVI cameras for HDCVI DVR (when buying a 2 MP HDCVI camera, make sure that the DVR supports it)!

Recently, new models of recorders have appeared on the market, to which you can connect both AHD and HDTVI, and old analogue and digital IP cameras. However, in reality, everything turns out to be not so smooth, so when choosing an analogue camera, be guided by the principles described just above.

Pros/cons of analogue cameras:

+ ease of connection, connected the wires - and it works;

+ work at long distances (300-500m) without additional equipment for signal amplification;

+ low cost;

- require a video recorder;

— problems with the compatibility of cameras of different standards.

Analogue cameras are easy to connect and can work on long distances (300-500m) without additional equipment

An IP camera differs from an analogue one in that it takes on the functions of a video recorder: video is digitized directly in the camera, and video can also be recorded on a memory card in it. Being connected to the network, the IP camera can independently interact remotely with any device capable of receiving its digitized video signal. It can even work with the "cloud". And for remote access to the camera using P2P technology, literally any mobile gadget or PC can be used.

As already mentioned, the “horse” of IP cameras is resolution. However, when choosing multi-megapixel IP monsters, remember that a very high resolution image has a downside! High bitrate video puts a significant load on the Ethernet local area network. If several alarm IP cameras suddenly start transmitting high quality video at the same time, it can “put down” the network. Therefore, when installing numerous high-resolution IP cameras, you should take care of the network infrastructure with proper bandwidth in advance and be sure to test the project at peak load.

Many IP cameras support PoE technology, that is, they are able to use the same cable for video signal transmission and power supply. This is a good solution in the sense that you do not have to rack your brains on how to bring a 12-volt power cord to the cameras as well. However, do not forget that the network equipment to which PoE cameras will be connected must also support this technology!

Pros/cons of IP cameras:

+ digital signal of IP cameras is much less affected by electromagnetic interference;

+ good compatibility with equipment from various manufacturers of network equipment;

+ simple integration on the basis of an existing local computer network;

- high price;

- complex connection with setting the IP address and options through the web interface;

- wired connection is limited to a distance of 100 m.

Housing type and installation location

Surveillance cameras are represented mainly by cylindrical and dome options, as well as rotary controlled (PTZ, aka SpeedDome) models.

Bullet cameras are mostly outdoor devices. Indoors, dome cameras are commonly used, as they fit much better into the interior. Indoor dome cameras look more attractive, do not "bulge" out of the design of the room as much as cylindrical ones. Keep this in mind when choosing a camera! However, outdoor dome cameras also exist, and in particular, they are optimal for installation in various unheated premises - warehouses, utility rooms, open areas, etc.

Cylindrical chambers are mostly designed for mounting outdoors, indoors are usually used domed

How is the outdoor camera different? If we are not talking about dubious cheap crafts that are not worth buying, then outdoor cameras are distinguished by a durable metal dust and moisture-proof housing with a protection class of at least IP65 - IP66 (the higher the better). Such cameras can easily withstand high humidity, precipitation, large daily temperature fluctuations, severe winter frosts or summer heat. It is not uncommon for outdoor cameras to be claimed to be vandal-resistant. Examples of affordable and modern cylindrical outdoor analogue cameras: Dahua DH-HAC-HFW1000R , interVision HD-X-1500W , Tecsar AHDW-1M-20F-Eco , Hikvision DS-2CE16C0T-IR .

Indoor cameras, designed for indoor installation, usually, come in less durable plastic cases and are cheaper than outdoor ones. Examples of indoor domes: Hikvision DS-2CE56C0T-IRMM , Dahua DH-HAC-HDW1100R , Tecsar AHDD-1M-20V-In .

An outdoor camera can be used as an indoor camera, but not vice versa!

Where possible, wired cameras should be preferred. Wireless cameras cannot yet boast of the main thing - the reliability of video signal transmission over household Wi-Fi networks.

Features of using cameras depending on the installation location:

- outdoor cameras can be used outdoors and indoors;

- indoor cameras can only be used indoors;

- Dome cameras look much better indoors by design;

- For reliable operation, give preference to cameras with a wired connection.

Features

What are the fundamental differences between cameras in terms of functionality? Actually a lot...

If you plan to organize video surveillance at the entrance to your home or office, you can choose a camera with a built-in microphone and speaker. Such a camera will make it possible to organize audio-visual communication with visitors like an intercom, but with a much better image quality. There are camera models with audio input and output - in this case, you can connect an external microphone to the device, placing it at some distance from the camera.

An outdoor camera can be used as an indoor camera, but not vice versa!

If the task is specifically security surveillance, it is worth looking at camera models equipped with an alarm input and output for connecting to an alarm system.

When it is planned to use the camera autonomously, for example, in a country house or in a country house to record the movement of "uninvited" visitors during the absence of the owners, then here you can look in the direction of IP cameras with recording on a memory card. Such a camera, hidden in the interior or exterior of the building, will capture all visitors, recording when movement is detected, and the owners will then be able to see who was roaming the site.

If you plan to install the camera near a railway or near a freeway, choose a model with image stabilization - and the camera will not be afraid of vibrations from passing traffic nearby.

When the camera is installed alone, and the controlled area is large, you will have to look at controlled PTZ(Pan-Tilt-Zoom) / SpeedDome cameras. Such devices are able to rotate the lens in a horizontal and vertical plane, carry out automatic control over the territory using programmed tours and viewing points, are able to monitor objects moving around the territory, etc. There are similar camera models with very long-range lenses and powerful night illumination at a distance of 100 m or more, which allows you to control vast areas - for example, one Tecsar AHDSD-2M-120V-out AHD camera is capable of monitoring an area of up to 45K square metres. metres. However, PTZ cameras are expensive and their mechanical drives require periodic maintenance. Actually, for these two reasons, controlled cameras have not gained too much popularity in video surveillance. In most cases, they prefer to get by with simple and “fail-safe” stationary cameras. There is a reason for this from the point of view of security: after all, while the PTZ camera “turned” to the side, for example, “buying” into a distraction, an attacker can slip through unnoticed in another place.

Analogue and IP cameras have roughly the same configuration options. Some of the analogue models have their own OSD menu, others are configured through the DVR. IP cameras are configured through a web or mobile application. The settings of a modern camera should not be small.

A good camera should provide:

- automatic exposure (AE) function, which sets the required shutter speed and aperture value to provide a normal level of image brightness;

- auto-correction of white balance (AWB), adjusting the colour reproduction as closely as possible to the real one, depending on the lighting conditions;

- it is highly desirable to have a backlight compensation algorithm (HLC / BLC), which allows you to level the effect on the image of a bright light source directed directly into the camera lens. These can be, for example, car headlights, lanterns, decorative lighting elements, etc.;

- 3DNR 3D noise reduction algorithm, which is designed to eliminate matrix noise in poor lighting conditions. Noise detection using the 3DNR method is performed not for one frame, as in the simpler 2DNR function, but for several consecutive frames at the same time. This allows you to more accurately highlight the noise, which changes over time much more than the main image. By the way, many indoor cameras are limited by the 2DNR function, but it is not so critical there - after all, the indoor camera usually works either in good light or in the dark, while the outdoor one has to work in difficult conditions of dawn and dusk, when noise significantly affects the image;

- The Flicker Reduction (FLK) function can be used to reduce image flicker when shooting under fluorescent lighting. Fluorescent lamps have a flickering frequency imperceptible to the eye, but easily fixed by the sensitive matrix of the video camera. This feature is especially relevant for cameras that are used near fluorescent lamps or in rooms lit by such lamps;

- for street cameras, the Defog anti-fog function is relevant, which, unfortunately, is not found in all cameras. This function makes it possible to obtain a clearly distinguishable image in conditions of poor visibility: in fog, smoke, dust. Usually the improvement in this case is carried out by the camera's microprocessor by correcting the gamma of the image. Cameras with this function will be especially relevant at facilities near water bodies, at enterprises with high levels of dust in the air due to production processes, etc.;

- It is preferable to choose a camera that can use a wide dynamic range(WDR). Alas, not all cameras have learned how to work with a wide range of shades so far ... When the lens simultaneously captures bright and dark areas of the image, a WDR-enabled camera dynamically changes the exposure, trying to capture the maximum brightness and colour gradations. As a result, very bright objects become darker and are better distinguished in the frame, while dark objects become lighter and do not lose detail due to a lack of contrast. Thus, the WDR function makes it possible to transmit the image as reliably as possible and without loss of detail;

- the video surveillance camera must (!) Have infrared night illumination. Thanks to such a backlight, the device is able to shoot high-quality images in very low ambient light levels and even in complete darkness - for example, indoors with the lights turned off. Here it must be said that camera lenses tend to defocus the image when switching to the infrared range. This is physics: long infrared rays are refracted by lenses differently than shorter wavelengths of visible light, so the focal length of the lens shifts significantly. This used to be a problem, but now even inexpensive cameras have lenses with IR filters that eliminate this unwanted effect. But if you plan to buy an old used camera, pay attention to the presence of such a useful IR filter there. Otherwise, you will either have to periodically adjust the focus, or “average” the blur in day / night modes, losing a little in detail, or reconcile with the low definition of the picture in the “night” mode.

Additional useful features that can be configured for almost any camera and which should not be forgotten:

— private zones, allow you to hide certain areas from video surveillance. Why is this needed? For example, the camera in the boss's office can shoot visitors as much as necessary, but it has no right to shoot the boss sleeping at the workplace, right ?;

- motion detection with the ability to automatically start recording. In this case, usually, both the motion detection area and the detection sensitivity are adjusted;

— detection of camera closure by an intruder;

- and sending an alarm notification, push or e-mail directly from the IP camera or analogue camera recorder.

Choice by lens type and matrix

The camera "sees" the world around it through the lens. Therefore, the image quality of the camera largely depends on its characteristics.

Pay no attention to the megapixels of the lens - once it is installed in the camera, it means that everything is fine in terms of megapixels

Manufacturers are very fond of writing all sorts of nonsense about camera lenses. For example, they will gladly tell you that a 1-megapixel or 2-megapixel camera has a 3-megapixel lens. Who cares? No one, except for the sellers themselves. The smartest of them are not even shy about selling cameras like 3 megapixels through various online stores. This, of course, is simply a fraud of the buyer. Serious manufacturers do not allow themselves this. Here's another argument in favor of serious manufacturers ... In general, do not pay attention to the megapixels of the lens - since it is installed in the camera, then everything is fine in terms of megapixels. But it is worth paying attention to the focal length.

The rule here is simple - the shorter the focal length, the wider the angle of view of the lens. But at the same time, the image detail is less, small details are less distinguishable. As the focal length increases, the viewing angle narrows, but the objects in the frame become larger and visible in more detail. If you connect the camera yourself and are not sure how optimally it will be possible to strike a balance between coverage of the territory and detailing of individual image objects, take a model with a varifocal lens. A varifocal is a lens with a variable focal length, which makes it possible to adjust the viewing area as flexibly as possible. However, ceteris paribus, the image of a lens with a fixed focal length is still better than that of a varifocal one. At the same time, cameras with fixed lenses are also cheaper ... By the way, in many cameras it is possible to replace a fixed lens with a lens with a different focal length. The most common lenses with a focal length of 2.8 mm, 3.6 mm, 4 mm, 6 mm, 8 mm, 12 mm, etc. But buying additional lenses is an expensive pleasure, and it’s not clear where to put the old one.

For those who need a 360-degree view from the camera, there are two options. The first is to purchase a controllable rotary PTZ model. The second is to buy a fixed camera with a fisheye lens (Fisheye) that provides a continuous 360-degree view. However, the detailing in the latter case, usually, leaves much to be desired. An example of such a camera is Hikvision DS-2CD6332FWD-I .

Keep in mind that objective lenses collect light not only within the angle of view, but also from bright side light sources. This leads to the appearance of unwanted “flare” of image fragments and causes a decrease in overall contrast. With increasing focal length, the harmful effect of side "flare" increases. The main source of this kind of glare for outdoor cameras is the Sun, which is constantly moving across the sky. To combat this problem in cylindrical outdoor cameras, visors are usually used, which simultaneously protect the lens eyepiece from water or snow ingress during heavy rainfall. Visors for cylindrical chambers are usually adjustable in length, although there are also fixed ones.

Keep in mind that cameras with fixed lenses and varifocal lenses with manual zoom (which are not PTZ) only have the ability to digitally zoom (zoom) the image during playback. If you need a real optical image zoom, and not software image scaling, you will need a SpeedDome-controlled camera with a motorized zoom, for example, an IP video camera Hikvision DS-2DE7184-A , Canon VB-M600D , Axis M3006-V .

Image quality is also significantly affected by the size of the photosensitive matrix of the camera. The larger the matrix, the better the image will be and the lower the noise level, the greater the viewing angles will be with exactly the same lens. Consider this. Cheap cameras with tiny 1/4-inch sensors often show either noisy or “blurred”, fuzzy images - as a result of excessive noise control software. Avoid such decisions whenever possible.

Camera resolution selection

Here the rule is simple: a modern camera, both analogue and digital, should provide a minimum resolution of HD (1280x720), better - Full HD (1920x1080). Lower resolution cameras are yesterday. Higher resolutions are presented exclusively in IP camera models, while the use of very high video frame sizes is not always practical, while the size of the video archive increases significantly when high resolutions are used, as does the load on the data transmission network.

Forewarned is forearmed with knowledge! Good luck choosing!