Matrix type
Type of matrix installed in the camera of the video panel (see "Type").
— CMOS. She is CMOP. Relatively inexpensive matrices, which, nevertheless, provide good image processing speed with low power consumption, and also take up little space (which is very important for miniature cameras). Their main disadvantage is the increased tendency to the appearance of noise in the image, which is why the quality of this image is somewhat inferior to CMOS CCD.
— CCD. The Russian equivalent of the name is "PZS". Such sensors are somewhat more expensive than CMOS, due to the complexity of the design, and their size is somewhat larger. At the same time, they have more uniform characteristics and are not as prone to heat during operation, which reduces noise and has a positive effect on image quality — especially with a small amount of light.
Megapixels
The number of megapixels in the camera sensor, in other words, its resolution. A megapixel is one million light-sensitive dots (pixels) that make up an image; the resolution of modern matrices is very high, so it is more convenient to use just this method of designation. However, for call panels, the values are
1 MP,
1.3 MP and
2 MP. More advanced options are extremely rare.
The higher the resolution of the matrix, the higher the video resolution can be (see below), the more detailed the image can be provided by the door panel camera. At the same time, note that as the number of megapixels increases (without changing the size of the matrix), the size of each individual pixel decreases, which increases the likelihood of noise and deterioration in the overall image quality. Therefore, high resolution in itself is not necessarily a sign of high quality — a lot depends on other things, for example, on the size of the matrix (see above).
Video resolution
The maximum video resolution that the call panel camera can provide.
The higher the resolution of the video, the more details you can see on it, the less details will be blurry. On the other hand, high resolution means large volumes of video materials, which, accordingly, requires fast communication channels, and this indicator significantly affects the cost of the device.
Video resolution (TVL)
Resolution of the image produced by the camera of the video panel (see "Type"). In such cameras, an analogue signal transmission format is used, and for it the resolution is usually indicated not in pixels horizontally and vertically, but in TVL — TV lines. This is due to the fact that the image in the analogue PAL and NTSC colour systems always has the same vertical size — 625 lines. Therefore, to indicate the differences between "pictures" of different resolutions, it is enough to know the horizontal size — i.e. number of lines.
In fact, this parameter describes the quality of the image that is displayed directly on the screen connected to the camera. The higher the resolution in TVL, the more detailed the image will be produced by the camera; this is especially important for models with wide viewing angles (see below). On the other hand, in order to use all the features of a camera with numerous TV lines, a screen corresponding to these features is also required; For more details on compatibility with the screen, see specialized sources.
Horizontal viewing angle
Horizontal size of the video panel covered by the camera (see "Type"); this size is most conveniently indicated by the angle between the lines connecting the camera lens with the left and right edges of the scene being viewed.
Theoretically, the wider the viewing angle, the more space the camera is able to cover and the less likely it is that some details will remain out of the frame. At the same time, taking into account the specifics of the use of outdoor panels, it is usually not necessary to equip them with wide-angle cameras; moreover, such optics would be inconvenient due to distortion and reduction effect. Therefore, most models have horizontal viewing angles in the range of 60 – 80 ° — this is quite enough for the intended use.
Focal length
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 above): 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.
