Sensor size
The physical size of the camcorder sensor. It is usually measured diagonally and is indicated in fractions of an inch — for example, 1/3 "or 1/2.33" (the second option is larger, respectively). In addition, sensors of a “photographic” format can be installed in video cameras, in which case the corresponding designation is used — for example, APS-C.
The larger the sensor, the higher the image quality it can provide (all else being equal). This is due to the fact that on larger sensors, each individual pixel is larger, more light falls on it, which increases sensitivity and reduces noise; this is especially important for shooting in low light. For amateur purposes, small sensors are quite enough, but in professional cameras (see "Features") this parameter is at least 1/3". The exception, however, are models with several sensors (see "Number of sensors") in them each individual sensor is quite small, and high quality is ensured by image processing features.
Focal length (35mm equivalent)
Focal length of a standard video camera lens in terms of a 35 mm full-frame sensor. This parameter is also called the "equivalent focal length" — EFL.
The focal length itself is the distance from the optical centre of the lens (when focus to infinity) to the sensor, at which the sharpest image is obtained on the sensor. It is one of the key characteristics of any lens, because. determines the viewing angles, the degree of approximation and, accordingly, the specifics of the use of optics. At the same time, it is impossible to compare different options in terms of the actual focal length: the laws of physics are such that with different sizes of sensors, the same focal length will give different viewing angles. Therefore, EFL was adopted as a universal characteristic and criterion for comparison. It can be described as the focal length that a 35mm lens with the same viewing angles would have.
The larger the focal length, the narrower the viewing angle will be and the higher the degree of approximation of the visible scene. Optics with EFL up to 18 mm belongs to the class of ultra wide-angle ("fisheye") and is used primarily to create artistic effects. Distances up to 40 mm correspond to "wide angles", 50 mm gives the same degree of approximation as that of the naked eye, the range of 70-100 mm is considered optimal for portrait shooting, and large values allow the use of optics already as a telephoto lens. Knowing these provisions, one can approximately...evaluate the capabilities of the lens and its suitability for certain tasks; there are more detailed recommendations, they are described in special sources.
Also note that modern video cameras are usually equipped with lenses with a variable focal length (zoom), which allows you to change the degree of approximation and viewing angle; see "Optical Zoom" for details.
Optical zoom
The degree (multiplicity) of image magnification provided by the operation of the lens system in the lens itself, without additional digital processing (see "Digital zoom"). Optical zoom involves changing the focal length (see above): the longer the focal length, the smaller the viewing angle and the larger the objects visible in the frame. And the zoom multiplicity corresponds to the ratio between the maximum and minimum value of this distance. For example, in a 24 – 120 mm system, this parameter will be 120/24 = 5x. However, it is not always appropriate to choose a
high zoom camcorder.
The advantage of optical zoom over digital zoom is, first of all, high image quality: regardless of the degree of zoom, the camera uses the entire effective area of the sensor. At the same time, zoom indicators can reach several tens of times, which is more than enough for camcorders of any class. Therefore, this format is the main one today; it is not used only in some models of pocket cameras (see "Features"), where it is not possible to install a large lens with a zoom lens.
For modern models, the value of this parameter at the level of 10 – 12x is considered standard.
Digital zoom
The degree (multiplicity) of zoom provided by the camcorders due to software methods, without changing the focal length of the optics (see "Optical zoom"). The key principle of such an zoom is that part of the image from the sensor is "stretched" to the entire frame. This somewhat worsens the “picture” — after all, not all effective pixels take part in its formation; and the higher the zoom, the worse the quality becomes. On the other hand, this method does not depend on the specifications of the lens and works even with the simplest lenses that do not have zoom lenses, and it is much easier to achieve high magnification than with the optical method.
In modern camcorders, there are two options for using digital zoom. So, among pocket devices (see "Features"), it may be the only available option — not all of them are equipped with zoom lenses. And in full-size models, digital zoom usually complements optical zoom and turns on after the lens reaches the limit of its capabilities.
Note that when shooting 3D (see above), this feature may not be available, and in professional models it is often not used at all.
Filter diameter
The diameter of the mount designed to install an additional filter on a regular camera lens. Such filters can have different types and purposes: UV filtering, colour correction, polarization, artistic effects, etc.; to select them for a specific camera model, you need to know the diameter of the mount.
