Comparison Canon 24-70mm f/4L EF IS USM vs Canon 17-40mm f/4.0L EF USM

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 o...f up to 40 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 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.

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.

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.

The number of blades provided in the design of the diaphragm (for details, see "Minimum aperture"). In fact, this parameter is important when shooting scenes with pronounced bokeh (blurred background) and a small depth of field: the more petals the aperture has, the smoother the glare from out-of-focus objects will turn out, while with a small number of petals they can look like polygons. The number of aperture blades has almost no effect on other shooting parameters. Modern lenses have an average of 7-9 petals; the smoothing provided by them in most cases is considered quite sufficient.