Comparison Sigma 24-70mm f/2.8 Art OS HSM DG vs Sigma 24-70mm f/2.8 AF EX DG Macro

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.

Macro photography is the shooting of small objects (for example, flowers, insects, clockwork) from an extremely close distance, sometimes measured in millimetres. In this case, the image of the object occupies a large part of the frame (often almost the entire one), which gives the effect of a significant increase and makes it easy to see details in the picture that are usually almost invisible to the human eye. For such shooting, both lenses specially designed for it and universal models with the appropriate mode can be used.

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.

This parameter determines the size of the area of the scene being shot that falls into the frame. The wider the viewing angles, the larger the area the lens can capture in one shot. They are directly related to the focal length of the lens (see "Focal length"), and also depend on the size of the specific matrix with which the optics are used: for the same lens, the smaller the matrix, the smaller the viewing angles, and vice versa. On our website, in the characteristics of optics, viewing angles are usually indicated when used with the matrix for which the lens was originally designed (for more details, see "Matrix Size").

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.

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).

The presence in the lens of its own image stabilization system. Such a system includes gyroscopes and movable lenses that compensate for small tremors of the lens and prevent the appearance of “shake”. Stabilization is especially relevant when shooting handheld, especially at slow shutter speeds and/or at long distances with high magnification: it is in such conditions that “shake” affects the quality of the image the most. At the same time, it should be taken into account that the presence of a stabilizer significantly affects the weight, dimensions and, above all, the price of optics; at the same time, some modern cameras have their own stabilization systems (due to matrix shift). Therefore, it makes sense to choose a lens with this function in the case when maximum protection against “shake” is of fundamental importance.