Comparison Dahua DH-HAC-HDW1800MP 2.8 mm vs Hikvision DS-2CE16U0T-ITF 2.8 mm

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.

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).

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 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.

The highest resolution at which the camera is capable of recording video at a frame rate of at least 25/30 fps. The parameter is specified for models that have high resolution shooting with a low frame rate (for example, 4K at 15 fps). It gives an understanding of the specific resolution at which video recording is supported with a frame rate of 25/30 fps, at which the picture is perceived smoother and details in dynamic scenes are better seen (if there are moving objects in the frame).

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.

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.

The signal-to-noise ratio that the surveillance camera corresponds to.

This indicator describes the ratio of the level of the useful signal (the actual image produced by the camera to an external device) to the level of extraneous noise that inevitably arises during the operation of electronic circuits. Such noise appears in the image as characteristic noise (“snow”). The higher the signal-to-noise ratio, the less interference on the screen, the clearer and better the image is, and the smaller the volume of recorded video files. It is believed that visible noise practically disappears at a ratio of at least 45 dB. However, among modern cameras there are also higher rates.

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.