Camera type
The type of cameras standardly supplied with a video surveillance kit.
- Directed. Directional cameras are those in which the lens “looks” along the body. This arrangement allows the use of powerful lenses with good aperture and optical zoom (see below), but the cameras also turn out to be quite bulky.
- Dome. In accordance with the name, on the body of such a camera there is a characteristic transparent dome, inside of which there is a lens - usually controlled by PTZ. The dome not only protects the optics from various adverse factors (for example, dirt or moisture), but in many models it also hides the position of the lens; for this purpose it is made dark. Thus, the subject of surveillance does not know where the camera is pointing, which can be useful in some cases (for example, when monitoring a suspicious visitor in a supermarket). At the same time, for a number of reasons, this option is poorly suited for advanced optics with large dimensions.
— Directional and dome. The presence of two types of cameras in the kit allows you to build a video surveillance system out of the box, covering both indoor and outdoor spaces. The details of each type are described above.
Dome cameras
The number of dome cameras supplied as standard with the video surveillance kit. For more information about this variety, see "Type of cameras", here we note that the total number of cameras in the set (both pointed and dome cameras), usually, is less than the number of video channels (see above). This allows you to buy additional cameras if necessary, and the user can choose them at his discretion.
Camera model
A model of dome cameras supplied as standard with a video surveillance kit. Knowing this data, you can find detailed information on the cameras and clarify their characteristics. In addition, by purchasing additional cameras of the same model, you don't have to worry about compatibility.
Martix type
Type of matrices used in complete dome cameras.
— CMOS. Also known as CMOS. Matrices of this type have good speed, small size, low power consumption and lower cost than CCD. On the other hand, the image quality of CMOS matrices is somewhat worse, and the noise is noticeably higher. However, these shortcomings can be corrected with the help of constructive tricks, and the technology itself is constantly being improved. Therefore, today CMOS matrices can be found both in inexpensive and in fairly advanced cameras; the actual quality of the sensor usually depends on the price category of the camera.
— CCD. Another well-known name is CCD. Compared to CMOS, such matrices are much more expensive and thicker, but they have lower noise levels and noticeably improve image quality. Of the practical disadvantages of CCD, it is worth noting that it is difficult to properly process point light sources; however, in many cameras, this moment is compensated to one degree or another by special technologies. Matrices of this type are typical for cameras of the middle and top levels.
— DIS. The main feature of DIS matrices is the presence of a built-in image processor in the sensor itself. This allows you to achieve good image quality with small dimensions and low cost of the cameras themselves (although they are still more expensive than CMOS).
Matrix size
The physical size of the sensor in the complete dome cameras is diagonally, in inches (fractions of an inch).
The larger the sensor, the less prone it is to noise, the better image quality it can provide, and the better it is suited to low light conditions. This is due to the fact that each individual pixel gets more light, because. on a large matrix and individual dots are larger. On the other hand, large matrices are more expensive.
Number of megapixels
Resolution of sensors of complete dome cameras in megapixels (millions of pixels).
Higher resolution allows you to get a more detailed "picture". However, increasing the number of megapixels without increasing the sensor size can result in poor overall image quality and noise, especially in low light. Therefore, in itself, the high resolution of the matrix does not guarantee high quality shooting.
Focal length
Focal length of the dome camera lens included in the kit.
The focal length is the distance between the lens and the matrix, at which the image on the sensor is as clear as possible (when the lens is focused to infinity). This indicator directly affects the viewing angles and the degree of magnification: the larger the focal length, the narrower the viewing angle and the more the camera "brings" the object. At the same time, it should be noted that the actual viewing angle is determined not only by the focal length, but also by the size of the matrix (see above). In fact, this means that with different sizes of matrices, lenses with the same focal length will have different working angles. Therefore, only cameras with the same matrix size can be compared with each other according to this indicator.
Illumination range
The range of infrared illumination provided in the standard dome cameras of the kit.
IR illumination allows the camera to shoot in low light conditions (up to complete darkness); at the same time, for a number of reasons, it is preferable to classical backlighting in the visible range. The backlight range is the approximate distance from the camera to the object at which it (in total darkness) will be normally visible in the frame. Note that actual visibility may vary greatly depending on the size, colour and reflectivity of specific items; Nevertheless, the claimed backlight range allows you to fairly accurately assess the "night" characteristics of the camera.
HDMI
The number of
HDMI connectors provided in the design of the complete registrar.
The HDMI interface is actually a standard for modern video equipment, it is widely used in TVs, monitors, projectors, etc. Usually, in modern registrars we are talking about HDMI outputs. This output allows you to broadcast a digital signal to an external screen, such as a TV; at the same time, both video and audio are transmitted via a single cable, and the bandwidth is enough to work with HD resolutions and multi-channel audio. The recorder itself can be used as an external video player, to play the footage, or directly broadcast video / audio from the camera (cameras) via HDMI. Models where there are more than one such outputs are practically never found.
