Body type
The case type describes not only its shape, but also some layout features that can affect the functionality of the product.
—
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 — and, usually, controlled by PTZ (see "Camera capabilities"). The dome not only protects the optics from various adverse factors (such as dirt or moisture), but in many models it also hides the position of the lens; for this it is darkened. Thus, the object of observation does not know where the camera is pointed, which is useful in some cases (for example, when observing 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.
—
Directed. Directional cameras are called cameras 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 are also quite bulky.
— Directional (
without a lens). A variation of the directional cameras described above, which has interchangeable lenses; The lenses themselves are usually not included in the kit, they must be purchased separately. The meaning of such a configuration is that the user can independently choose optics for specific needs. This categor
...y includes mostly fairly advanced models.
— Hidden. This category includes cameras of a small size, which allows them to be installed discreetly — for example, in a wall niche. However, even with an external installation (this option, usually, is also allowed), such devices are also very inconspicuous due to the mentioned compactness. By itself, the body shape of hidden cameras is most often close to directional (see above), although there may be different options.
— Desktop. Cameras designed to be mounted on a tabletop or other flat, horizontal surface. For this, an appropriate stand is provided in the design; it can have movable mounts that allow you to tilt the camera and rotate it from side to side. The main advantage of such cameras is the utmost ease of installation; this, in particular, makes them almost perfect for home use.
— Portable with fastening. In fact, it is a kind of desktop cameras (see the relevant paragraph), in which the stand can be used not only for installation on a horizontal surface, but also for wall mounting. From other "wall" varieties — hidden and directional (see relevant paragraphs) — cameras of this type differ in layout: their body is usually flat, rectangular or oval, and the lens is located on the widest edge (similar to how it is done in mobile phones ). The mount is often made movable, to adjust for tilt and/or rotation.Max. memory card size
The largest capacity of a memory card with which a video surveillance camera can work correctly.
High-capacity drives require fairly high processing power and may use special technologies that are not supported by all cameras. This is the reason for the limitation on the volume of supported media.
Number of LEDs
The number of backlight LEDs (see "Design and capabilities") provided in the camera design.
Theoretically, more LEDs provide more power and, accordingly, range (see below) and efficiency
of IR illumination or LED illumination. However, in fact, such light sources can vary markedly in performance; in addition, a lot also depends on the features of the camera itself. Therefore, in fact, this indicator is a reference, and when choosing, it makes sense to pay attention to parameters that are closer to practice — in particular, the same backlight range (see below).
Illumination range
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.
Frame rate
The maximum frame rate in the video captured by the camera.
The higher the frame rate, the clearer the image, the less noticeable blurring when moving in the frame (especially fast). On the other hand, this indicator affects the amount of information recorded during shooting, as well as the cost of the camera itself. Therefore, it makes sense to specifically look for
a video surveillance camera with high-speed shooting(45 fps and higher) only if a clear recording of fast moving objects is important to you.
Aperture
Aperture of the lens installed in the camera.
Aperture characterizes the degree of attenuation of the light flux when passing from the front lens of the lens to the matrix. It is denoted as the ratio of the diameter of the active aperture of the lens to the focal length, while the size of the active aperture is designated as f and is taken as a unit — for example, f / 1.4 or f / 2.0. Moreover, the smaller the number in the designation, the higher the aperture (in our example, the second lens will be darker than the first). And for lenses with a variable focal length (see "Focal"), the actual aperture, usually, changes with a change in focal length; for such models, either the range of aperture values, or its maximum value, can be indicated.
By itself, this parameter characterizes, first of all, how light the image taken through the lens turns out, all other things being equal. High values are important, first of all, when shooting in low light conditions: a fast lens allows you to get a fairly high-quality image without increasing the sensitivity of the matrix, which is fraught with noise and “blurring” of the picture. On the other hand, the actual quality of camera operation (including in dark conditions) also depends on many other factors — the type and size of the matrix, signal processing features, etc. Therefore, aperture in most cases is more of a reference than a practically significant parameter.
Focal length
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
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
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.