Comparison Panasonic AG-AC30 vs Panasonic AG-AC90

The number of individual light sensors installed in the camera. In our catalog, this parameter is indicated only for models that have more than one sensor.

There are two main varieties of multi-sensor cameras. The first is professional models that carry three sensors on board. Each of them works with only one colour, which allows you to get an image with good clarity and high colour accuracy. Of course, the actual quality of the "picture" largely depends on a number of other parameters, but initially a three-sensor scheme provides better image quality than a single-sensor one.

The second option is 3D camcorders (see "Features"), in which two sensors can be installed — each for its own video channel. See "3D" for more details.

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.

The number of light sensitive pixels directly involved in the construction of the image. These are the dots on which the “image” projected by the lens onto the matrix falls. In addition to them, there are also service pixels that are not illuminated during camera operation — they provide auxiliary information necessary for processing the resulting image. Also, when calculating effective megapixels, the reserve area required for electronic stabilization is usually not taken into account (see "Image Stabilization").

The value of the number of effective pixels for different modes of operation of the camcorder will also be different. For example, when recording video, many cameras use multiple pixels to build a single dot on the image; this is due to the fact that the sensor resolutions significantly exceed those required for video shooting (for example, the Full HD standard technically corresponds to only 2.07 megapixels). As a result, the image quality depends more on the sensor size (see above) than on the resolution. And among sensors of the same size, high resolution allows user to get better colour rendering and higher clarity (however, not always — a lot also depends on the peculiarities of image processing). If we are talking about photography, then more megapixels means a higher resolution of the resulting image, but the quality of such a picture can be relatively low due to the increased noise level and low sensitivity of each individual pixel.

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.

Aperture of a standard video camera lens.

This parameter describes how much the lens attenuates the light output. Usually it is written as a ratio between the diameter of the active hole and the focal length of the lens, while the first value is taken as one and denoted as f — for example, f/1.8 or f/5.6. Moreover, the smaller the number in such a record, the higher the aperture ratio: for example, in our example, the first option is “lighter” than the second. Also note that most lenses with a variable focal length (see above) also have a variable aperture — in such cases it is indicated by the range from maximum to minimum (from a smaller number to a larger one).

A high aperture ratio is important primarily when shooting in low light conditions: it allows you to capture an image without “lifting up” the sensor sensitivity and without creating additional artifacts in the form of noise, and in the photo shooting mode, you can also work with shorter shutter speeds (which is useful for dynamic scenes). In addition, the higher the aperture, the lower the depth of field and the easier it is to get a blurry background. Note that for simple everyday tasks this parameter does not play a decisive role, but in professional shooting it can be very significant.

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.

An image stabilization method provided in the design of a video camera. The stabilization function itself is designed to compensate for small camera shakes so that they are not noticeable in the image. This is especially true when shooting handheld, and in fact most modern models are designed specifically for such usage. According to the method of work, there are such options:

— Optical. A special mechanism with a system of gyroscopes and movable lenses, installed directly in the lens, is responsible for the operation of such stabilization systems. It introduces a correction for all tremors, vibrations, etc., and the “picture” falls on the already stabilized sensor. Optical systems are considered the most advanced and efficient, because. their work allows you to use the entire area of the sensor, fully exploit its capabilities and provide good image quality. Among the shortcomings, it is worth noting the increase in the cost and weight of the cameras, as well as a slight decrease in the reliability of the optics. At the same time, these moments are most often not critical, and stabilizers of this type can be used even in simple and inexpensive models.

— Electronic. Electronic stabilization is carried out due to the fact that not the entire area of the sensor, but only some of it, is involved in the formation of an image for a frame. Simply put, the camera electronics "takes into account" a certain area of the sensor and...transfers the image from it into the frame; and at small displacements, this "area of attention" is also displaced, due to which the visible image remains motionless. The advantages of electronic systems are simplicity of design, lightness, compactness and high reliability; they can be used with even the simplest lenses installed in pocket cameras (see “Features”). Their main disadvantage is the need to reserve a part of the sensor, which reduces the size and resolution of the actually involved area and adversely affects the image quality.

— Optical / electronic. In such systems, both the methods described above are used — both the mechanism in the lens and the reserve on the sensor. This provides extremely high vibration compensation efficiency — the image remains stable even in such conditions in which any single method would be useless. On the other hand, the disadvantages of both options also remain relevant, and the cost of cameras with this feature is quite high.

The highest frame rate provided by the camera when shooting video. The minimum frequency for normal viewing is the classic 24 fps used in cinema. At the same time, most modern video cameras are capable of providing up to 50 – 60 fps, and even higher frequencies can be used for the slow motion effect.

In fact, this indicator is important primarily when shooting dynamic scenes. The higher the frame rate, the smoother the fast motion will look in the frame, the less jerky it will be and the more pleasant the overall impression of the image will be. The reverse side of this is an increase in the size of recorded files (all other things being equal). Therefore, the frame rate can be made adjustable so that the operator can choose the best option for a particular situation.

Video file formats that the camera can use to store recorded footage. If you want to view these materials using a separate device (player, media centre, etc.), you should make sure that this player supports the appropriate formats, otherwise conversion may be necessary.