Comparison Sigma 30mm f/2.8 Art DN vs Sony 20mm f/2.8 E

General type of lens. It is worth considering that this parameter is largely determined by the equivalent (not actual) focal length, while optical specifications usually list the actual value; for more details, see "Focal Length."

The type is specified not for every optic but only for models with a clearly defined specialization that fit neatly into a specific category. Besides them, there are so-called universal lenses — see below for more about them. Specialized models can fall into the following types:

— Prime. This category on our website includes virtually all lenses that do not allow for changing the focal length. These can be wide-angle models or optics with a long focal length that offers a high degree of magnification, as well as models with medium values; the only exception is the ultra-wide-angle "fisheye," which is classified as a separate type (see below). Due to their simpler construction, primes are usually cheaper and more reliable than similar zoom models. Their main disadvantage is their fixed focal length. Because of this, using primes for each type of shooting requires its own lens, and zooming is exclusively done by moving the camera closer or further from the subject (in professional slang — "foot zoom").

— Wide-angle. Lenses with a variable focal length, with a minimum value of up to 18 mm inclusive, and a maximum of up to 4...0 mm inclusive (both in 35 mm equivalent). This ensures a wide viewing angle with virtually no visible distortions (unlike ultra-wide-angle models, see below). "Wide angles" are often used for landscape photography, large objects, etc.; such a lens can also be useful in tight spaces where capturing the broadest possible scene is necessary (for example, a large group of people), and the setting doesn't allow stepping back far.

— Ultra-wide-angle. This type of lens is also known as fisheye. Their equivalent focal length is up to 17 mm inclusive, and the viewing angles can reach up to 180° and even more, allowing capturing a very extensive area of the surrounding space in a single shot (for example, the entire sky around the horizon). Such lenses are characterized by noticeable distortions in the resulting image: the center of the frame appears closer than the edges, and straight lines not passing through the center of the frame become curved. Because of this, fisheye lenses got their name: the view through them resembles how a fish would see the ground from underwater. Most frequently, fisheyes have fixed focal lengths, but zoom options also exist. These lenses are particularly used for creating panoramas, shooting in confined spaces, and providing artistic effects.

— Telephoto. Lenses with a long focal length and, consequently, a high degree of magnification, primarily intended for shooting over long distances. In terms of specific figures, in our catalog, telephoto lenses include models with a variable focal length, where the lower boundary of the focal length is no less than 50 mm, and the upper boundary is no less than 200 mm. Such optics are especially convenient for nature photography, sports events, and large gatherings.

— Anamorphic. A special type of lens that compresses the image horizontally during shooting, and then stretches back during playback, creating a characteristic wide cinematic format with impressive light flares (anamorphic "flares") and shallow depth of field. These lenses are used to create an atmospheric, cinematic visual style, especially sought after in video making, allowing a wide frame without losing vertical resolution.

Besides the types described above, numerous lenses are produced that meet the criteria of several types or do not fit into any of them. As an example, an intermediate option between wide-angle and telephoto lenses with a focal length from 24 to 55 mm or a model with a wide adjustment range like 28–200 mm, covering both types, can be cited. Such lenses are commonly referred to as universal. Overall, their application area is quite broad, and the mentioned "intermediate option" includes most optics supplied in a kit with DSLR cameras. However, in terms of photo quality, universal models often fall short of specialized optics of a similar price; on the other hand, a set of several specialized lenses often costs more than a high-class "universal" with the same capabilities.

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.

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 number of elements (in fact, the number of lenses) included in the design of the lens, as well as the number of groups in which these elements are combined. Usually, the more elements provided in the design, the better the lens handles with distortions (aberrations) when light passes through it. On the other hand, numerous lenses increases the dimensions and weight of the optics, reduces light transmission (for more details, see "Aperture") and also puts forward increased requirements for the quality of processing, which affects the cost of the lens.