Fotokursy Uncategorized Lenses and their variety

Lenses and their variety

We purchase cameras, as a rule, with a “kit” lens (English kit – kit, kit). In the process of shooting, the photographer becomes interested in other optics and And then the race for the dream lens begins. 🙂

Lenses and their variety
The viewfinder is our eyes in the camera. The main function of the lens is to refract light rays so that they, having passed through the optical system, are correctly displayed on the photosensitive element: a matrix or film.

Lens construction. Diaphragm. Depth of field
The lens consists of a lens system, a metal or plastic frame and a diaphragm. Depending on the quality of the lens, the number of lenses and their groups varies.

The lenses are made of optical glass and assembled into a single system inside the frame. The quality of the image largely depends on the accuracy of their relative position. The diaphragm is a partition with a round hole of variable diameter. Its purpose is to let in the amount of light we need, adjusting the sharpness of the image. That is, it serves to change the depth of sharply depicted space (DOF).

DOF is the range or area of ​​sharpness in front of and behind the subject. If the range is small, they speak of a shallow depth of field, if it is large, a large depth of field. The range becomes smaller as the aperture value decreases.

The concept of lens aperture is directly related to aperture.

Aperture refers to the maximum amount of light a lens can let through. In relation to the lens, this is also the value of the maximum open aperture. Therefore, if we talk about the types of optics, fast lenses should immediately be singled out as a separate group. They are highly translucent. By the way, these include not only f / 1.4 or f / 1.8 lenses. The 200mm f/2.8 lens is also fast.

The main feature of such optics is the ability to take high-quality pictures in low light conditions, create frames with a shallow depth of field. Depending on the quality of the lens, the beauty and pattern of the background changes.

Focal length: angle of view
The angle of view is the space that enters the frame and is displayed on the light sensor. It is measured in degrees. The human visual angle is 50-55 degrees. Focal length is inextricably linked with this concept. These are the numbers that lenses are marked with. Focal length is measured in millimeters. The smaller the value, the wider the angle and the larger its numerical value, and the more space fits into the frame. As the focal length increases, the viewing angle decreases. Based on these differences, lenses can be classified into wide angle (short throw), normal (medium) and tele or long throw.

Wide-angle lenses are lenses with an angle of view of 52 degrees or wider.

In the equivalent focal length, these will include lenses with a focal length of up to 35–37 mm. They visually distance objects. Their main purpose is shooting in limited and enclosed spaces (when it is necessary that as much space as possible fits into the frame). When shooting on a wide-angle, one should be aware of geometric distortions (distortions), which are an integral feature of this kind of lenses.

The next group includes the so-called “normal” lenses. The angle of their vision is close to human vision.

Shooting, in fact, is carried out on the basis of “what I see is what gets into the frame.” The main focal lengths of normal lenses include 40–60 mm (equivalent). A “normal” lens is a staff member. It is commonly confused with a “kit” lens. The last is called the lens from the kit.

And the last group includes long-focus or telephoto lenses (FR 70–75 mm and more).

The main purpose of televisions is to shoot distant objects. They can also be used for portrait photography.

Depending on the range of focal lengths, all lenses are divided into discrete (with a fixed focal length – fixes) and zooms (with a variable focal length, zoom). The most popular fix is ​​“fifty kopecks” (FR 50 mm). With zooms, the focal length changes. The most commonly used zoom lens is the 18-55mm kit lens.

There are lenses for full-frame SLR cameras, the sensor size of which is similar to the frame size of a 35 mm film camera (24 × 36 mm), and for APS format DSLRs. The latter may not be suitable for full-frame cameras, because they have a different mount (for example, Canon cameras). When using full-frame lenses on cameras with APS sensors, the focal length of the lens should be multiplied by the crop factor of the camera.