Comparison Sigma 24-70 f/2.8 Art DG DN vs Sigma 24-70mm f/2.8 Art OS HSM DG

The general purpose is rather conditional, and in fact the use of optics is not limited to the claimed direction — it all depends on the skills and imagination of the photographer. However, information about the specialization can greatly facilitate the choice. Considering such original options as a cinema lens and a multifunctional.

— Architectural. Lenses designed primarily for shooting buildings. Most of these models are equipped with the Tilt-Shift system (see below). In this case, this function is intended to correct the perspective when shooting tall buildings. In a photograph taken with a normal lens, straight lines can turn out to be curved, which is unacceptable in cases where an accurate representation of the building in the picture is required. Using the Tilt-Shift system allows you to avoid this phenomenon and get a reliable image that does not require additional correction in a photo editor.

— Landscape. In this case, landscape lenses include short-focus (wide-angle) lenses, which, according to test results, provide good image sharpness. In other words, not all “wide-angles” are classified as landscapes, but only those that are actually capable of providing a clear, sharp image.

— Portrait. The hallmarks of a classic portrait lens are: first, the fixed focal le...ngth, which is usually over 50mm (35mm equiv.); secondly, high aperture (most often not lower than f / 2.8, although occasionally there are exceptions). This combination of characteristics allows you to shoot portraits with beautiful background blur, placing the camera at a fairly significant distance; the latter can be useful in studios where additional lighting equipment is used — it is advisable to install the camera behind lighting fixtures so that it does not give a shadow. Speaking of a fixed focal length, it is worth recalling that "fixes" are simpler, lighter and cheaper than zoom lenses, and the ability to adjust the magnification when shooting portraits is rarely required — most often you can completely get by with "zoom with your feet".

— Multifunctional. This direction includes lenses of a universal type (see above), offering the buyer a good value for money; in other words — multi-purpose models with good performance and at the same time relatively inexpensive (namely, "comparatively", the actual price can be quite high). When choosing models in this category, the quality of filming was evaluated according to the results of real tests.

— Film lens. The main feature of cinema lenses is the ability to fine-tune the aperture. The aperture can be closed / opened by 0.1 or even 0.01 mm, while in photo lenses the aperture setting step cannot be less than 1 mm. Additionally, in cinema lenses, aperture is expressed by a T-number, and in photographic lenses, an F-number is used. The operator can shoot multiple cinema lenses with the same aperture, without the need to change the lighting. And when using photo lenses with the same aperture, you often have to adjust the lighting for each optic separately. Cinema lenses are meant to be shot from a tripod, which is reflected in their design features and design — such models are usually larger and heavier than their counterparts for photography.

The result shown by the lens in the DxOMark rating.

DxOMark is one of the most popular and authoritative resources for expert testing of photography devices. According to the test results, the lens receives a certain number of points; The more points, the higher the final score.

The system indicates which brand of cameras this lens is designed for. Manufacturers of photographic equipment often use original mounting systems in their cameras that are not always compatible with each other; therefore, for normal use, the lens must be originally designed for the corresponding system. At the same time, note that the actual compatibility will also depend on the mount (see "Bayonet (mount)"). At the same time, one system often includes several mounts (for example, Canon and Nikon); it happens vice versa — one mount can be used in several systems at once (for example, Micro 4/3 is used by both Olympus and Panasonic). In general, the optimal selection order is as follows: first clarify the compatibility of the lens with the system, then with a specific mount.

Also note that third-party manufacturers (who do not produce cameras and deal only with lenses) often produce models designed for several different systems at once. Such compatibility can be achieved both through a set of adapters (included in the package or sold separately), and through the release of different modifications of the same lens, differing only in mounts. The features of each such model should be specified separately.

The type of mount used to connect the lens to the camera. The name comes from the English "bayonet", meaning "bayonet" and a bayonet-type connection. Bayonet mounts are used in the vast majority of modern digital cameras due to their reliability and ease of use.

Full compatibility of the lens with the camera is guaranteed only if the types of their mounts match. Some mounts are compatible with each other via adapters, but such a connection can limit the capabilities of the lens (for example, it will make it impossible to use autofocus) and is generally not considered optimal. It is worth considering that within the same system (see above) different mounts are often used, which are also incompatible with each other.

So, the manufacturer Canon has mounts EF-M, EF-S, EF, RF, RF-S. Leica has Leica M, Leica SL, Leica TL. Nikon has Nikon 1, Nikon F, Nikon Z in its arsenal. Pentax optics are equipped with Pentax 645, Pentax K, Pentax Q. Samsung uses NX-M and NX mounts. Sony models include Sony A and Sony E. In addition, there are other types of mounts on the market - both branded ( Fujifilm G, Fujifilm X, Hasselblad H, Sigma SA) and universal ( Four Thirds (4/3), Micro 4/3).

Note that there are lenses that are declared compatible with several mounts at once. This “omnivorousness” can be realized in different ways. For example, some models have a non-standard mount on the lens body, and compatibility with various mounts is ensured through the use of adapters; These adapters can be included in the delivery set or purchased separately. Another option is that the lens is available in several separate modifications, each for its own mount. These details should be clarified before purchasing.

Minimum focus distance (m) - the smallest distance from which you can focus on an object and take a photo. Usually it ranges from 20 cm for wide-angle lenses to several metres for telephoto. In the macro mode of the camera or with the help of macro lenses, this distance can be less than 1 centimeter.

The degree of magnification of the object being shot when using a lens for macro shooting (that is, shooting small objects at the maximum possible approximation, when the distance to the subject is measured in millimetres). The degree of magnification in this case means the ratio of the size of the image of the object obtained on the matrix of the camera to the actual size of the object being shot. For example, with an object size of 15 mm and a magnification factor of 0.3, the image of this object on the matrix will have a size of 15x0.3=4.5 mm. With the same matrix size, the larger the magnification factor, the larger the image size of the object on the matrix, the more pixels fall on this object, respectively, the clearer the resulting image, the more details it can convey and the better the lens is suitable for macro photography. It is believed that in order to obtain macro shots of relatively acceptable quality, the magnification factor should be at least 0.25 – 0.3.

The size of the matrix for which the lens was originally designed.

The formats (and sizes) of modern matrices can be indicated diagonally in inches (1/1.8", 1/2.3" — in this case, the conditional "Visicon" inch is taken, which is about 17 mm), according to the actual dimensions (13.2x8.8 mm) or by symbol (APS-C, full frame). In general, the larger the sensor, the more advanced and expensive it is.

Among modern lenses, solutions for such matrix formats are most popular, in ascending order of size: 4/3(17.3x13 mm, used in cameras of the Four Thirds and Micro Four Thirds standards), APS-C(23x15 mm with slight variations, SLR and MILC cameras of the middle class), full frame(36x24 mm, the size of a standard film frame — advanced DSLRs), big frame(anything larger than full frame — high-end professional cameras). Optics for other formats is somewhat less common.

Note that it is technically allowed to use with “non-native” sensors, however, in such cases, the performance characteristics of the optics will differ from those claimed. So, when installed on a smaller matrix (for example, a full frame lens on an APS-C camera), only a part of the image created by the lens will fall on such a sensor. As a result, the space that gets into the frame will be narrower, and the details in the frame will be larger, as if the focal...length of the lens has increased (although it has remained unchanged, only the matrix has changed). And when installed on a larger sensor, the covered space will increase, the detail will decrease; in some cases, the size of the “picture” provided by the lens may simply not be enough for the entire area of the matrix, and the pictures will be obtained with black space around the edges.

A type of drive that ensures the movement of lens structural elements during automatic focus. Currently, the following types can be used:

— Ultrasonic motor. The most advanced type of drive to date. Ultrasonic motors are much faster than conventional motors, provide higher accuracy, consume less power and are virtually silent. However, their cost is quite high.

— Stepper motor. Drive control focal length and zoom (zoom). This type of motor is used for the most part only in full-size digital cameras. Among the advantages of a stepper motor, one can note: high reliability and accuracy of operation; in addition, it does not require power supply to maintain focus and zoom. Of course, stepper motors are not without drawbacks. Among the minuses can be identified: slow speed and increased noise. Additionally, a stepper motor is characterized by large dimensions and a rather large weight, which physically does not allow this type of drive to be integrated into the optics of mobile phones and ultra-compact cameras.

— Motor. In this case, an electric motor of a traditional design is meant. Such drives are simple and, as a result, inexpensive. Their disadvantages are the relatively low speed of operation, as well as the noise produced during this; the latter can sometimes be critical — for example, when shooting wildlife. Recently, designers have been us...ing various tricks to neutralize these shortcomings, but in general, the characteristics of conventional motors still remain relatively modest.

— Is absent. The complete absence of an autofocus motor in the lens. Focus such optics can be carried out either by the “screwdriver” system, or strictly manually (for more details on both options, see below).

Lenses using the internal focus system. In such optics systems, focus is carried out only due to the movement of elements inside the lens body; the outer parts remain completely fixed and the size of the lens does not change. This provides additional convenience — in particular, it allows you to easily use petal hoods and those types of filters for which the correct position on the lens is important (in particular, gradient ones). In addition, the absence of moving elements from the outside has a positive effect on security and resistance to dust / precipitation (although the specific degree of dust and water protection may be different).