Comparison Canon IXUS 185 vs Canon Digital IXUS 190

Aperture of the lens installed in the camera or supplied with it in the kit (for models with detachable optics).

In a simplified way, this parameter can be described as the ability of the lens to transmit light - in other words, how much the light flux weakens when passing through the optics. It is believed that two main indicators affect the characteristics of light transmission: the size of the relative opening of the lens and its focal length. Aperture is the ratio of the first indicator to the second; in this case, the size of the active hole is taken as one and is generally omitted when recording, as a result, such a recording looks, for example, like this: f / 2.0. Accordingly, the larger the number after the fraction sign, the lower the aperture ratio, the less light the lens transmits.

Zoom lenses (zoom lenses), as a rule, have different aperture values for different focal lengths. For such optics, two values of this parameter are indicated in the characteristics, for the minimum and maximum focal lengths, for example, f / 2.8–4.5. There are also vario lenses that maintain a constant aperture over the entire range of focal lengths, but they are much more expensive than analogs with variable aperture.

The high light transmission of the lens is important if the camera is planned to be used for shooting in low light conditions or for shooting fast moving objects: high-aperture optics allow you to shoot at low sensor sensitivity (which...reduces the likelihood of noise) and at low shutter speeds (at which moving objects are less blurry) . This parameter also determines the depth of field of the imaged space: the higher the aperture ratio, the smaller the depth of field. Therefore, for shooting with artistic background blur (“bokeh”), it is recommended to use fast lenses.

Focal length of the camera lens.

Focal length is such a distance between the camera matrix and the optical center of the lens, focused at infinity, at which a clear and sharp image is obtained on the matrix. For models with interchangeable lenses ( mirrorless cameras and MILC, see “Camera Type”), this parameter is indicated if the camera is supplied with a lens (“kit”); Let us recall that, if desired, optics with other characteristics can be installed on such a camera.

The longer the focal length, the smaller the viewing angle of the lens, the higher the degree of approximation and the larger the objects visible in the frame. Therefore, this parameter is one of the key for any lens and largely determines its application (specific examples are given below).

Most often in modern digital cameras, lenses with a variable focal length are used: such lenses are able to zoom in and out of the image (for more details, see "Optical Zoom"). For "DSLRs" and MILC, specialized optics with a constant focal length (fixed lenses) are produced. But in digital compacts, "fixes" are used extremely rarely, usually such a lens is a sign of a high-end model with specific characteristics.

It should be borne in mind that the actual focal length of the lens is usually given in the characteristics of the camera. And the viewing angles and the general purpose of the optics are determined not only by this parameter, but also...by the size of the matrix with which the optics are used. The dependence looks like this: at the same viewing angles, a lens for a larger matrix will have a longer focal length than a lens for a small sensor. Accordingly, only cameras with the same sensor size can be directly compared with each other in terms of lens focal length. However, to facilitate comparisons in the characteristics, the so-called. EGF - focal length in 35 mm equivalent: this is the focal length that a lens for a full frame matrix having the same viewing angles would have. You can compare by EGF lenses for any matrix size. There are formulas that allow you to independently calculate the equivalent of 35 mm, they can be found in special sources.

If we talk about a specific specialization, then the EGF up to 18 mm corresponds to ultra-wide-angle fisheye lenses. Wide-angle is considered "fixed" optics with EGF up to 28 mm, as well as vario lenses with a minimum EGF up to 35 mm. Values up to 60mm correspond to "general purpose" optics, 50 - 135mm are considered optimal for shooting portraits, and higher focal lengths are found in telephoto lenses. More detailed information about the specifics of various focal lengths can be found in special sources.

The magnification factor provided by the camera by using the capabilities of the lens (namely, by changing its focal length). In models with interchangeable lenses (see “Camera type”), indicated for the complete lens, if available.

Note that in this case the magnification is indicated not relative to the image visible to the naked eye, but relative to the image produced by the lens at minimum magnification. For example, if the characteristics indicate an optical zoom of 3x, this means that at the maximum magnification, objects in the frame will be three times larger than at the minimum.

The degree of optical zoom is directly related to the range of focal lengths (see above). You can determine this degree by dividing the maximum focal length of the lens by the minimum, for example 360mm / 36mm=10x magnification.

To date, optical zoom provides the best "close" image quality and is considered to be superior to digital zoom (see below). This is due to the fact that with this format of work, the entire area of \u200b\u200bthe matrix is constantly involved, which allows you to fully use its capabilities. Therefore, even among low-cost models, devices without optical zoom are very rare.

An image stabilization method provided by the camera. Note that systems of the optical type and with a sensor shift are sometimes combined under the term "true" stabilization - due to their effectiveness. See below for more on this.

By itself, stabilization (regardless of the principle of operation) allows you to compensate for the effect of "shake" with an unstable camera position - especially when shooting handheld. This is especially true when shooting with a significant increase or at slow shutter speeds. However, in any case, this function reduces the risk of spoiling the frame, so cameras with stabilization are extremely common. The principles of work can be as follows:

— Electronic. Stabilization, carried out due to a kind of "reserve" - a section along the edges of the sensor, which initially does not participate in the formation of the final image. However, if the camera electronics detect fluctuations, it compensates for them by selecting the necessary image fragments from the reserve. Electronic systems are extremely simple, compact, reliable and at the same time inexpensive. However, for their work it is necessary to allocate a fairly significant part of the sensor - and reducing the usable area of the sensor increases the noise level and degrades the image quality. And in some models, electronic stabilization is turned on only at lower resolutions and is not available at ful...l frame size. Therefore, in its pure form, this option is found mainly in relatively inexpensive cameras with non-replaceable lenses.

- Optical. Stabilization, carried out when light passes through the lens, is due to a system of movable lenses and gyroscopes. As a result, the image hits the sensor already stabilized, and the entire sensor area can be used for it. Therefore, optical systems, despite the complexity and rather high cost, are considered more preferable for high-quality filming than electronic ones. Separately, we note that in SLR and MILC cameras (see "Camera Type") the availability of this function depends on the lens installed; therefore, for such models, optical stabilization is not indicated in our catalog in principle (even if the complete lens is equipped with a stabilizer).

- With sensor shift. Stabilization, carried out by shifting the sensor "following" the shifted image. Like the optical one described above, it is considered a fairly advanced option, although in general it is somewhat less effective. On the other hand, systems with a sensor shift have serious advantages - first of all, the fact that such stabilization will work regardless of the characteristics of the lens. For cameras with fixed lenses, this means that the lens can do without an optical stabilizer and make the optics simpler, cheaper and more reliable. In SLR and MILC cameras, the sensor shift makes it possible to use even “non-stabilized” lenses with convenience, and when installing “stabilized” optics, both systems work together, and their efficiency is very high. In addition, sensor shift is somewhat simpler and cheaper than traditional optical stabilizers.

— Optical and electronic. Stabilization that combines both of the options described above: initially it operates according to the optical principle, and when the capabilities of the lens are not enough, an electronic system is connected. This improves the overall efficiency compared to purely optical or purely electronic stabilizers. On the other hand, the disadvantages of both options in such systems are also combined: the optics are relatively complex and expensive, and not all of the sensor is involved. Therefore, such a combination is rare, mainly in separate advanced digital compacts.

- With sensor shift and electronic. Another type of combined stabilization systems. Like “optical + electronic”, it improves the overall stabilization efficiency, but at the same time it combines the disadvantages of the two methods (they are also similar: the complication and rise in price of the camera, plus a decrease in the useful area of \u200b\u200bthe sensor). Therefore, this option is used extremely rarely - in single models of digital ultrazooms and advanced compacts.

File formats in which the camera can record video. Given that the footage is designed to be viewed on an external screen, you should make sure that the playback device (DVD player, media centre, etc.) is able to work with the appropriate formats. At the same time, many camera models themselves can play the role of a player by connecting to a TV via an audio / video output or HDMI (see the corresponding paragraphs of the glossary). And if the video materials are to be viewed on a computer, you should not pay special attention to this parameter at all: problems with format incompatibility in such cases rarely occur, but are usually solved by installing the appropriate codec.

The minimum/maximum distance from the subject to the lens at which the flash can be used effectively (usually limited to a few metres). Since lenses with a variable focal length have different aperture ratios depending on the set focal length (see Aperture), for cameras with such optics, two ranges of flash application are indicated — for the minimum and maximum focal lengths, for example "0.3 — 3.5 (W), 0.45 — 2(T)." The letters W and T in such markings indicate the minimum and maximum focal lengths, respectively.

The maximum number of photos that the camera can take on a single battery without recharging/replacing it. In fact, this number usually turns out to be less (sometimes quite noticeable) due to the fact that part of the charge is “eaten up” by the lens mechanics, using the display, changing settings through the menu, etc. Nevertheless, this parameter is a good indicator of the battery life of the device, and different models can be compared with each other.