Comparison Hikvision DS-2CD2T85G1-I8 vs Hikvision DS-2CD2085FWD-I

Operating range of the backlight (see "Design and capabilities") installed in the surveillance camera. This term usually means the maximum distance from the camera to the observed object, at which it is able to provide a relatively high-quality and legible image in the complete absence of other light sources. Of course, the actual backlight range may differ from the claimed one, and these differences are most often in the direction of increase (for example, due to the presence of the same additional light sources). However, if the possibility of shooting with backlight is important for you, you should focus on the claimed range.

Functions that automate the process of video monitoring, analysis and response to events, which helps to minimize the human factor and increase the efficiency of video surveillance systems.

— Perimeter protection. This option is used when deploying complex video surveillance systems with a recorder and cameras, combining the expanded functionality of intelligent video analytics capabilities for monitoring boundaries. Perimeter protection can cover various functions, for example, tracking the intersection of virtual lines, the appearance or disappearance of objects in the frame, setting up protected zones, if the boundaries of which are violated, an alarm will be activated, and so on. The full list of features should be specified separately. It is important to note that for the listed functions, analysis of objects in the frame can be used - detection of people, classification of vehicles, etc.

— Definition of a person. Cameras with this function can detect the presence of people in the frame by the characteristic outlines of their silhouettes. Once a person's presence is detected, an alarm can be activated, and moving PTZ cameras can follow people in the frame.

— Definition of a car. The ability of a video surveillance camera to automatically recognize and highlight objects in the frame that are vehicles. This can be useful for monitoring t...raffic, controlling parking, or ensuring the safety of roads within a controlled perimeter. A more advanced implementation of this function is license plate recognition (see below).

— Definition of animal. The function of identifying various “living creatures” in the frame: pets, neighbor’s cats and dogs, alien wild animals, etc. Video surveillance systems with this functionality can be used to minimize false alarms, monitor pets to make sure they are safe and in order, and to solve other similar problems.

— License plate recognition. Special tools that provide additional capabilities for reading license plates. The specific capabilities of such tools may be different in different models; they should be clarified separately. So, some cameras only read letters and numbers and transmit the information to the recorder for further processing. Others have built-in databases, so they can compare the read number with the base and provide various actions depending on the result - for example, send a signal to open the barrier if the number is “allowed”. However, in any case, cameras with this feature are well suited for objects where it is necessary to control the movement of cars - for example, parking lots (including closed service ones).

— Facial recognition. Cameras with this function are able to at least recognize the presence of faces in the frame; but the further use of this data and the special functionality of such cameras may be different. Thus, relatively simple models react only to the very fact of detecting a face, but even this provides quite extensive additional capabilities: focusing on a face, tracking a person in the frame (in moving PTZ cameras), etc. And more advanced cameras can recognize characteristic features faces by which a specific person can be identified. This functionality, among other things, allows the surveillance system to compare the faces “seen” by the camera with the stored database and take various actions based on this - for example, allow or deny access, warn about an unwanted visitor or unauthorized use of a key card, etc. P.
Note that face recognition tools can also be found in recorders to which cameras are connected. However, the presence of such functions in the cameras themselves can also be useful - especially if the existing recorder “does not shine with capabilities” in this regard, or the system does not have a recorder at all (for example, it consists of IP cameras connected via a router to a PC).

— People counting. A function that allows the camera to count the number of people in the frame; the received data is stored in its own memory and can be sent to a recorder or other external device. Note that in most models this feature is combined with the face recognition described above, thanks to which the camera is able not only to count all people in a row, but to recognize tech who are in the frame again. However, people counting can be used for both statistical and security purposes. For example, at large facilities such as office and shopping centers, it allows you to determine whether all visitors who entered the premises left it before the end of working hours.

The size of the matrix installed in the surveillance camera (diagonally).

In general, larger sensors (with the same resolution and sensor type) are considered more advanced: they get more light, which has a positive effect on image quality (especially in low light). On the other hand, increasing the size affects the cost of the entire device; and in some cases (for example, if the camera is not planned to be used in twilight and darkness), a relatively small sensor may be quite suitable.

As for specific dimensions, the most modest cameras in terms of this indicator have matrices of 1/4 "or less. Models with sensors of 1/3.8" - 1/3" and 1/2.9" - 1/2" are very popular, these values can be called average. And in advanced devices, diagonals and more than 1/2 "(up to 1/1.7") are found.

The lowest degree of illumination of the scene being shot, in which the camera is able to provide normal visibility. Usually, this item specifies the values for the daytime mode of operation (in the night mode, the minimum illumination in many models may be zero at all, because in such cases the IR illumination is turned on, see "Design and capabilities"). And if the camera is capable of shooting in colour, it usually means the lowest illumination necessary to obtain a colour image.

The lower this indicator, the better the camera works in low light, the brighter and more clearly visible image it is able to provide in such conditions. At the same time, note that in low light, night mode is often preferable, and in the presence of the aforementioned IR illumination, it is more likely to focus on the range of its operation (see above).

There are comparative tables that allow you to evaluate the degree of illumination indicated in the characteristics from a practical point of view: for example, an indicator of 0.2 lux corresponds to clear eyes on a full moon.

Focal length of the camera lens.

The focal length is such a distance from the lens to the matrix, at which a clear image is obtained on the matrix (when the lens is focused to infinity). The viewing angles of the lens primarily depend on this indicator (see below): the smaller it is, the wider the viewing angles and the smaller the objects in the frame (and vice versa). 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. Among CCTV cameras, lenses with a focal length of 2.8 mm, 3.6 mm, 4 mm and 6 mm are considered popular.

In models with a variable focal length (see above), in this case, the range from the minimum to the maximum distance is indicated. Also, using these data, you can derive the optical magnification factor of such a lens: for this, the maximum value must be divided by the maximum (for more details, see below).

Horizontal viewing angle of the surveillance camera. For models with a variable value, the maximum value is indicated, since it is the width of the image that is important, and when zooming in, the zoom factor is more important than the angle. This paragraph also indicates the general angle of view for models with a circular field of view – in particular, cameras with a fisheye lens (see above)

The wider the viewing angle, the more space the camera captures and at the same time, the smaller the images of individual objects in the frame are obtained. Therefore, when choosing by this parameter, it is worth deciding what is more important – the ability to view a large scene or the visibility of small details in a relatively narrow field of view. Also note that with a wide field of view (100° or more), characteristic distortions can be observed at the edges of the frame, and the wider the angle, the more pronounced they are. This phenomenon can be eliminated by panoramic shooting (see "Design and features"), but this feature, in turn, complicates and increases the cost of the camera.

Vertical viewing angle of the surveillance camera. In models with a variable value, the maximum is indicated, and the angle when zooming is not so important.

The wider the viewing angle, the more space the camera captures and at the same time, the smaller the images of individual objects in the frame are obtained. Therefore, when choosing by this parameter, it is worth deciding what is more important – the ability to view a large scene or the visibility of small details in a relatively narrow field of view.