How to change focal length. Lens focal length as one of the most important characteristics of photo optics
Camera lenses consist of several lenses that form an image on a matrix. And considering optical characteristics lenses replace a group of lenses with one for ease of understanding. By physical properties focal length lens - this is the distance from the optical center of the lens group to the matrix. This distance is measured in millimeters and written on the lens.
For photographers, it is much more important to understand the dependence of the resulting image on the focal length.
Based on the ratio of focal length (FL) and frame diagonal, lenses can be divided into three large groups s:
- If the DF is approximately equal to the diagonal of the frame (matrix), then such lenses are called normal.
- If the FR is less than the frame diagonal, then the lens short throw.
- If the FR is larger than the frame diagonal, then the lens is long-focus.
In photography, all calculations are carried out using the frame dimensions of 35 mm film, which is used in film cameras. So its diagonal is 43 millimeters. Likewise, in physics it is believed that for the visual angle of the human eye, a focal length of 50 millimeters is accepted as normal. Therefore, everywhere in photographic equipment the normal focal length is considered to be a distance of 50 millimeters.
Now you can divide lenses into types by focal length.
| Focal length | Lens type | Shooting goals | Viewing angle |
| 4 - 16 mm | fish eye | landscape, art, landscapes | 180° |
| 10 - 24 mm | ultra wide angle | interior, landscape, deliberate distortion of proportions | 84 - 109° |
| 24 - 35 mm | wide-angle | landscape, architecture, street photography | 62 - 84° |
| 50 mm (35 - 65) | standard | landscape, portrait | 46° (32 - 62) |
| 65 - 300 mm | telephoto lens | portrait, sport, nature | 8 - 32° |
| 300 - 600 or more mm | super telephoto lens | animals and sports from afar | 4 - 8° |
In this table you can see the dependence of the viewing angle on the focal length. It turns out that the smaller the FR, the larger the viewing angle. Taking pictures with a lens with a wide viewing angle changes the perspective of the image, this is reflected in a change in the proportions of the subjects being photographed.
With normal (standard) lenses, with a focal length of about 50 mm, the pictures are the most natural in perception. Best suited for street photography.
Lenses with focal lengths from 50 mm to 130 mm can serve as portrait lenses. The most suitable FR is 80 mm for creating portraits.
Variable focal length
Lenses are available with fixed or constant focal length and variable. On lenses with variable FR, a pair of numbers are indicated - long and short focus. Dividing one value by another we get the zoom factor, which is indicated on the camera.
The zoom factor does not at all mean how many times the object will be magnified; zoom only shows that the lens has a variable focal length. Today there are 80x zoom lenses. The disadvantage of such lenses is the reduction in aperture ratio. To achieve high aperture, lenses with a fixed focal length are used.
Focal length and crop factor
All of the above numeric values valid for 35 mm film and for digital matrices whose dimensions correspond to the frame of 35 mm film. Such matrices are called Full Frame.
But there are matrices different sizes and to make cameras cheaper they are made much smaller than Full Frame. Such matrices are called cropped, from the word crop (to cut).
This is how the crop factor appeared, which shows how many times the matrix is smaller than the film frame and this coefficient is equal to the ratio of the diagonal of the full frame to the diagonal of the matrix.
A Full Frame matrix will have a crop factor of 1.
And if the lens is used not with a full frame, but with such a cropped matrix, then the viewing angle changes. This matches virtual increase focal length. Although the real FR remains unchanged, because this is a characteristic of the lens. The crop factor is a reference factor and does not change the actual parameters of the lens.
For example, using a cropped matrix with a crop factor of 1.6, we find that a lens with a 50 mm PR with this sensor will already have a virtual PR of 50x1.6 = 80 mm. This focal length is called equivalent (EGF). That is, we take the focal length indicated on the lens and multiply it by the crop factor.
In the figure above you can see that by using a smaller matrix we get a smaller viewing angle, and this changes the boundaries of the image (reduces the boundaries). It seems that we enlarged the object by changing the focal length of the lens, but the FR remained the same.
The equivalent focal length is already more characteristics lens+matrix combinations.
Choosing a lens with a specific focal length depends on your creative preferences and frame composition.
Lens - essential element any camera. And focal length is the most important characteristic of a lens. However, novice amateur photographers experience complete confusion with this characteristic. They cannot understand: for example, a lens with a focal length of 24-70 mm on a full-matrix camera - is it good or bad? Is 15-44 mm on a “cropped” DSLR normal or not enough? Is 7.1-28.4 mm on a point-and-shoot camera quite small or is it still ok? Well, let's figure out what the focal length of a lens is and what its different values mean. A lens is a system consisting of several lenses. The image of the object being photographed enters the lens, is refracted there and reduced to one point at a certain distance from the back of the lens. This point is called focus(focus point), and the distance from the focus to the lens (lens system) is called focal length.
Now let’s talk about what these or other focal lengths mean in practical terms. Initially, let’s agree that we are now talking about a lens designed for shooting on a full-matrix camera (in this article we talked about what a “full matrix” is). Let's take a purely practical look at the differences between frames taken with one focal length or another. We shoot from one point and change focal lengths from 24 to 200 mm. Focal length 24 mm. 
Focal length 35 mm. 
Focal length 50 mm. 
Focal length 70 mm. 
Focal length 100 mm. 
Focal length 135 mm. 
Focal length 200 mm. 
Obviously, the shorter the focal length, the more is placed in the frame, and the longer the focal length, the closer the lens brings distant objects. Short focal lengths are used for shooting all kinds of images: landscapes, architecture, large groups of people. Long focal lengths are used for shooting, for example, animals and birds, for sports photography when you need to catch close up some spectacular shot. A focal length of 50 mm approximately corresponds to the viewing angle of the human eye (46°). Lenses with a focal length of less than 35mm are called wide-angle. With their help, it is convenient to photograph nature and architecture, however, it should be borne in mind that the wider the angle (smaller focal length), the greater the distortions caused by the laws of optics will be present in the photographs. For example, if you shoot high-rise buildings with a lens with a focal length of 24 mm, then closer to the edges of the frame on the right and left the buildings will appear tilted - here is an example. 
Lenses with a focal length of less than 20mm are called ultra-wide-angle lenses, and they distort the image very much. (There's more separate species fisheye lenses). Here is an example photo (from here) taken with a wide-angle fisheye at 8mm focal length. 
Lenses with long focal lengths are called “long focal lengths”, and those with very long focal lengths are called “telephoto lenses”. In general, the classification there is approximately as follows: Lenses come with a fixed focal length (the so-called “primes”) and with a variable focal length (the so-called “zooms” from the word zoom, bring closer). As a rule, lenses with a fixed focal length take better pictures (and are cheaper) than zooms set to the same focal length. That is, for example, in the general case, a 24 mm wide-angle will give better quality than a 24-70mm zoom set to 24mm. (There are exceptions, but we won’t get into those jungles now.) And now we have come to a very important issue. What is this strange range of focal lengths on my Fujifilm X20, you may ask? It says 7.1-28.4 mm. Is it like a super mega extra wide angle? No. The fact is that when we talk about cameras with a cropped matrix, the physical focal length of the lens does not change (it cannot change), however, since much less fits into the frame on a cropped matrix, it turns out that the “angle of view” of the lens narrows, and Accordingly, for a given matrix the focal length will be different. Precisely “as if different,” because if the lens has a focal length of 50 mm, physically it will remain that way on any matrices. But the shots will be different. I'll explain now. Let's say we have a lens with a focal length of 50 mm. It forms a circular image, which, superimposed on the full-size matrix, gives us a full frame - there it is, marked in the illustration. 
We put the same lens on a camera with a cropped matrix - for example, with a crop factor of 2. What will a frame taken with the same lens look like? It will appear within the blue rectangle in the illustration. That is, less. And less means the object will be closer, so it turns out that when shooting with a lens with a focal length of 50 mm on a camera with a crop factor 2 matrix, the focal length will be equivalent to shooting with a lens of 100 mm (50 mm times the crop factor) on the camera with a full-size matrix. The problem is that cropped camera lenses usually indicate the physical focal length of the lens. And in order to understand what these numbers generally mean, you need to multiply the specified focal length by the size of the crop - then you will get the numbers of the focal length (distances for zoom) in the equivalent of a full-matrix camera (35mm matrix) and you will understand what range of focal lengths is present in this camera Example. Fujifilm Finepix X20 camera, zoom range - 7.1-28.4 mm. The crop factor of this camera's matrix is 3.93. So we multiply 7.1 by 3.93 and 28.4 by 3.93 - we get a range (rounded) of 28-112 mm in 35 mm equivalent. In general, the most common range for a digital camera. Second example. Amateur DSLR with a kit lens. The lens has a range of 18-55mm. The crop factor of the matrix is 1.6. Multiply - we get 29-88 mm. The range is very so-so, but you can use it. Thus, in order to clearly understand what focal lengths are available in your camera (or in the camera you are going to buy), you need to multiply the focal range numbers indicated on the lens by the crop factor - this will give you data on focal lengths of 35- mm equivalent, which will be quite clear to you. It is clear that for full-format cameras with their “native” lenses, no recalculations need to be made. By the way, sometimes, for the convenience of users, manufacturers write on non-replaceable camera lenses both their physical focal length and its equivalent for 35 mm - like this, for example, Sony cameras RX10, where the physical range is 8.8-73.3, and with the 2.7 crop installed, an excellent range of 24-200 mm is obtained: from a good wide-angle to a very decent telephoto lens.
Understanding the features of lenses can help you take control of your digital photography. Choosing the right lens for a shooting task can be a complex trade-off between cost, size, weight, focusing speed and image quality. This chapter aims to improve understanding of these choices by providing an initial overview of the concepts of image quality, focal length, perspective, prime and zoom lenses, and aperture or f-number.
Lens elements and image quality
All cameras, except the simplest ones, are equipped with lenses that consist of several “ optical elements" Each of these elements helps direct the flow of light rays to recreate the image on the digital sensor as accurately as possible. The goal is to minimize aberrations while using the fewest, least expensive elements.
Optical aberrations occur when elements in a scene do not translate into similar elements in the image after passing through the lens, creating image blur, reduced contrast, or color mismatch (chromatic aberration). Lenses may also suffer from imbalance, vignetting, or perspective distortion. Hover over each of the options below to see how these defects affect image quality in extreme cases.
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| Original image | Loss of contrast | Blur |
| Chromatic aberration | Distortion of perspective | |
| Vignetting | Original | |
Each of these issues is represented to some degree in any lens. Later in this chapter, when a lens is referred to as having poorer optical quality than another lens, it means some combination of the defects described above. Some of these defects may be less objectionable than others, depending on the subject being photographed.
Effect of lens focal length
The focal length of the lens determines its angle of view and at the same time the degree of magnification of the subject at a given shooting point. Wide-angle lenses have short focal lengths, while telephoto lenses have long focal lengths.
Note: The point where the light rays intersect is not necessarily equivalent to the focal length as shown above, but the distance is approximately proportional. Thus, increasing the focal length actually reduces the angle of view, as illustrated.
Many will say that the focal length also determines the perspective of the image, but strictly speaking, the perspective only changes with the change in the position of the photographer relative to the subject. If you try to shoot the same subject with a wide-angle lens and a telephoto lens, the perspective will actually change as the photographer will have to move closer to or further away from the subject. Only in these cases will a wide-angle lens exaggerate or stretch the perspective, while a telephoto lens will compress or smooth it out.
Controlling perspective can be a powerful compositional tool in photography and often determines the choice of focal length (if it is possible to shoot from any position). Hover over the image above to see the shift in perspective due to the wide angle. Note that the objects in the frame remain almost identical and thus require a closer position for the wide-angle lens. The relative sizes of objects change so much that the distant door becomes smaller relative to the lamps in the foreground.
The following table provides information on what focal lengths are needed for a lens to be considered a wide-angle or telephoto lens, as well as their typical uses. Please note that Only approximate focal length ranges are indicated, And real application may vary accordingly; many, for example, use telephoto lenses when shooting long landscapes to compress the perspective.
*Note: Lens focal lengths are valid for cameras with sensor size equivalent to 35mm film. If you are using a compact or budget DSLR camera,
Most likely, the sensor size in it is different. To correct these numbers for your camera,
use the focal length converter in the chapter on digital camera sensor sizes.
Other factors may also depend on the focal length of the lens. Telephoto lenses are more sensitive to camera shake because minimal hand movement results in a significant shift in the image, as you can see if you try to hold binoculars with shaky hands at a close-up zoom. Wide-angle lenses generally have less glare, in part because they were designed with the idea that wide angles are more likely to let the sun into the frame. Finally, closer telephoto lenses generally provide better optical quality at a similar price.
Focal length and handheld shooting
The focal length of a lens can also have a significant impact on the ease of getting a sharp handheld shot. Increasing the focal length requires shortening the shutter time to minimize blur caused by hand shake. Imagine what it's like to hold still laser pointer: on a nearby object its beam jumps noticeably less than on a distant one.
This is because the slightest circular vibrations increase significantly with distance, whereas if the vibrations were only horizontal or only vertical, the distance from the laser to the object would be maintained.
Common practical method determining the required shutter speed for a given focal length divides unit per focal length. This means that for a 35mm camera, the exposure time should be no more than one divided by the focal length, a fraction of a second. In other words, when using a 200mm focal length on a 35mm camera, the shutter speed should be no more than 1/200 of a second, otherwise it will be difficult to avoid blur. Do not forget that this is an extremely rough rule; someone will be able to hold the frame much longer or, conversely, less. Owners of digital cameras with a smaller sensor will have to calculate the effective (true) focal length taking into account the frame size.
Variable lenses (zooms) and prime lenses (fixes)
A variable lens is one whose focal length can change within specified limits, whereas in “simple” or fixed lenses it is unchanged. The main advantage of a vari lens is the ease of achieving a variety of compositions or perspectives (since there is no need to change lenses). This advantage is often critical for dynamic shooting, for example, in photojournalism and children's photography.
Don't forget that Using zoom doesn't necessarily mean you don't need to move anymore; zooms just increase flexibility. The example below shows the starting position as well as two options for using a zoom lens. If a simple lens were used, changing the composition would not be possible without cropping the image (if the composition needed to be closer). Similar to the example in previous section, the change in perspective was achieved by shortening the focal length and moving closer to the subject. To get the opposite change in perspective, you would have to increase the focal length and move further away from the subject.
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| Two varifocal lens options: | |
| Changing the composition | Changing Perspective |
Why deliberately limit your capabilities by using a simple lens? Prime lenses existed long before the advent of vari lenses and still have many advantages over their more advanced counterparts. modern analogues. When zooms first came to market, using them meant sacrificing a lot of optical quality. However, newer, high-quality vari lenses generally do not introduce any noticeable deterioration in image quality unless scrutinized with a trained eye (or when printing a very large print).
The main advantages of prime lenses are cost, weight and speed (aperture). Inexpensive prime lenses can usually provide just as good (if not better) image quality than expensive vari lenses. Additionally, if we're looking at a zoom with a small focal length range, a prime lens with a similar focal length will be significantly smaller and lighter. Finally, the best prime lenses almost always provide best aperture(maximum aperture) than best zooms- which is sometimes critical for shooting sports or in a theater in low light conditions, when a shallow depth of field is needed.
For compact digital camera lenses that say 3x, 4x, etc. zoom, this number refers to the range between the shortest and longest focal lengths. So a higher number doesn't necessarily mean the image can be zoomed in further (as that zoom might simply have a wider angle at its minimum focal length). In addition, digital zoom is not the same as optical zoom, since it enlarges the image through interpolation. Read what is written small print to make sure you are not misled.
Effect of aperture or f number
The aperture stop range of a lens refers to the degree to which the lens can be opened or closed to let in more or less light, respectively. Apertures are specified in terms of f-numbers, which quantify the relative area of light transmission (shown below).
Note: This comparison is approximate: the aperture blades rarely form
an ideal circle, since the aperture usually consists of 5-8 blades.
Please note that what larger area light transmission, the less number f (this is often confusing). The two terms are often mistakenly used interchangeably. The remainder of this article considers lenses as apertures. Lenses with wider apertures are often called "faster", because the same ISO sensitivity may require a faster shutter speed for the same exposure. Additionally, a smaller aperture means that objects can remain in focus over a greater range of distances, a concept described by the term "depth of field".
When purchasing lenses, pay attention to the specifications, which indicate the maximum (and sometimes minimum) possible aperture. Lenses with large aperture ranges provide greater flexibility in both possible shutter speed and depth of field. Maximum aperture is probably the most important characteristic of a lens and is often listed on the box along with the focal length.
The f number can also be specified as 1:X (instead of f/X), as in Canon lens 70-200 f/2.8 (its box is shown above and it says f/2.8).
Shooting portraits, as well as in the theater or at sporting events, often requires the lens to have the largest possible apertures to ensure short excerpts or shallow depth of field, respectively. A shallow depth of field when shooting a portrait helps to separate the subject from the background. For digital cameras Lenses with larger apertures provide significantly more bright image in the viewfinder, which may be critical for shooting at night and in low light conditions. They often also provide faster and more accurate autofocus in low light conditions. Manual focusing is also easier, because the viewfinder image has a shallower depth of field (making it easier to see when the subject comes into focus).
Minimum lens apertures are usually not nearly as important as maximum apertures. They are rarely used due to image blur caused by diffraction, and because they can require impossibly long shutter speeds. In cases where extreme depth of field is needed, lenses with a smaller maximum aperture can be used ( a large number f).
Finally, some zooms on DSLRs and compacts digital cameras the range of maximum apertures is often indicated, since the aperture value can depend on the focal length. These aperture ranges only define the maximum apertures possible, not the full range. For example, f/2.0-3.0 means that the maximum possible aperture gradually decreases from f/2.0 (at the widest angle) to f/3.0 (at the maximum focal length). The main advantage of a variable lens with a constant maximum aperture is that exposure is more predictable regardless of focal length.
Please also note that even if a lens' maximum aperture cannot be used, this does not necessarily mean that the lens is not needed. Lens aberrations are typically smaller when exposures are used one or two f-stops below maximum aperture (for example, when using f/4.0 on a lens with a maximum aperture of f/2.0). This Maybe mean that for photography at f/2.8 aperture, an f/2.0 or f/1.4 lens can achieve more high quality than a lens with a maximum aperture of f/2.8.
Other considerations include price, size and weight. Lenses with large maximum apertures are usually much heavier, larger, and more expensive. Size and weight can be critical for filming wildlife, hiking and traveling, since in them the equipment must be carried for a long time.
Focal length (FR or ƒ) is the distance between the optical center of the lens and the camera sensor. The longer the focal length, the larger the scale of the image projected by the lens onto the sensor; the shorter the focal length, the smaller the scale of the image. We can say that a lens with a long focal length enlarges objects, as if bringing them closer to the photographer, and with a shorter focal length it reduces them, moving them away.
Focal length determines the lens' image angle (angular field). A lens with a long focal length has a narrow image angle - while magnifying objects, a long lens fills the entire frame with them. A short focal length lens, on the other hand, has a wide image angle and is able to capture large number space. For example, a lens with a focal length of 50 mm has an angular field of 47°, but with a focal length of 200 mm it will provide a field of view of only 12°.
Depending on the focal length and, accordingly, the image angle, there are three main groups of lenses: normal (or standard), long-focus (telephoto lenses) and short-focus (wide-angle).
Normal lenses, i.e. those that give an image closest in perspective to what is seen human eye, have a focal length approximately equal to the frame diagonal, or slightly longer than it. So, a frame of standard 35 mm film has dimensions of 36 x 24 mm, and therefore its diagonal is approximately 43.3 mm. Lenses with a focal length of about 40-60 mm are considered normal. In fact, 50 mm is most often used. This lens is also called “fifty kopecks”. The angular field of a standard lens lies in the range of 40-60°.
It has a focal length greater than the frame diagonal. Such lenses are used for shooting distant objects, as well as in cases where the background can distract attention from the main subject, and a small viewing angle of a telephoto lens is necessary to isolate the subject as much as possible, eliminating everything unnecessary from the frame.
Has a focal length less than the frame diagonal. Its wide angle is great when the background is important to the photo and you want to capture more space, emphasizing perspective and relationships between shots.
Long focal length lens – small image angle.
Short throw lens – wide image angle.
Most used focal lengths
and their corresponding image angles
The numbers in the table are valid for cameras shooting on 35 mm film (format 135), as well as for full-frame digital cameras with a sensor size of 36 x 24 mm (see “Photographic formats”). However, the vast majority of digital cameras have smaller sensors, and when using them it is advisable to have an understanding of crop factor and equivalent focal length.
Currently, lenses with variable focal lengths - the so-called varifocal lenses, zooms or zooms - have gained wide popularity. Their convenience and practicality are obvious - one zoom can replace a whole bag of lenses. The disadvantages are the complexity of the design and, as a result, high cost, large size and weight, as well as lower image quality compared to lenses with a fixed focal length.
Perspective management
The focal length of the lens, along with the position of the camera, affects the composition and perspective of the photo.
Imagine that you are taking a portrait of a person against the backdrop of some distant objects - let it be a mountain, the edge of a forest or any man-made structures. Let's take several photographs using lenses with different focal lengths, but at the same time we will try to keep the size of the person constant relative to the size of the frame.
When shooting with a normal lens, you will get a shot that has the most natural perspective, with background objects decreasing in proportion to their distance from the person in the foreground.
The photograph was taken using a standard lens.
If you take a long lens, you'll have to step back to compensate for its magnifying power and keep the subject's scale the same. At the same time, background objects will increase in scale and come closer to you. Why? Yes, because by moving an extra ten meters away from the person who was initially located five meters away from you, you tripled the distance between you, and the distance to the background, which may have been measured in tens, if not hundreds of meters, practically did not change. That's why they say that telephoto lenses compress plans, eliminating perspective distortions. In fact, the lens has nothing to do with it - it just magnifies the image without understanding where the background is and where the foreground is, but this allows you to shoot the subject at a greater distance, reducing the difference between the distances from you to different shots of the scene.
A telephoto lens brings the foreground and background of an image closer together.
Telephoto lenses are great for shooting portraits, as well as for macro photography, because, firstly, they depict all parts of the object on approximately the same scale, and secondly, due to the small angle of view, they allow you to exclude extraneous background elements from the frame. However, telephoto lenses also work great for landscape photography, when you want to bring distant objects closer together, creating a surreal perspective. As for photo hunting, a telephoto lens is almost indispensable here, although it does not relieve the photographer of the need to get as close to wild animals as possible, and even closer.
Let's return to our portrait, but now with a wide-angle lens. This time you need to approach the person at a distance of about two and a half meters. The background, which we are almost no closer to, will decrease in size and move back. Now endless spaces fit into the frame: mountains, forests, and high skies. If you crouch down and take a photo from a low point, your subject will appear to be a giant towering above the mountains, and the trees will begin to fall towards the center of the frame. A wide angle image allows all of these perspective distortions to be captured and emphasized, but they are created solely by the camera position and viewing direction. Distortions of perspective can become both an advantage and a disadvantage of a frame - decide for yourself in each specific case: to fight them, or, on the contrary, to aggravate them for greater effect.
A wide-angle lens emphasizes perspective.
Be especially careful with wide-angle lenses, because while they can include a lot of good things in the frame, they also make it difficult to exclude unwanted objects from the frame. Get into the habit of scanning the edges of the viewfinder while composing your shot, looking for various unplanned debris. Don't forget the importance of the foreground as well. The desire to cover many objects leads to the fact that they all turn out to be small and inexpressive. Try to find some interesting compositional center so that it attracts the eye to your photo. Moving closer always improves your photos. To emphasize the relationship between the plans, it is necessary, first of all, to have these plans.
Sometimes perspective distortion is a disadvantage,
and sometimes - dignity.
Wide-angle lenses are unsuitable for portraits, firstly because the wide angle of the image includes too many distracting background elements in the frame, and secondly because it forces you to get too close to the subject, and the model’s nose ends up in twice closer to the camera than her ears, doubled in the picture larger size. However, if you like such grotesquery, no one has the right to limit your creative imagination.
Warning
The least correct conclusion that can be drawn from reading the above is that you need to immediately acquire lenses that cover the entire range of focal lengths from 0 mm to infinity. Pathologically incorrect! You will look like a walking camera store, and rest assured that when you take a photo, you will always have the most inappropriate lens on your camera. You don't need the right equipment Maybe you will ever need, but only what you cannot do without. Before buying another lens, make sure that you clearly understand why you need it and what problems it is designed to solve. Better is one simple lens, which you will study perfectly and with which you can mentally see the future frame without looking into the viewfinder, than a dozen expensive pieces of glass in which you will get confused, and the combined weight of which will not allow you to walk even a kilometer without shortness of breath. Remember Henri Cartier-Bresson, who in his entire life never used another lens other than a single fifty-kopeck lens.
Believe me, the lens that was sold with your camera is a great lens, and its capabilities are enough to solve 90% of photographic problems. More expensive lenses will not improve the quality of your pictures, but will only slightly expand the range of situations in which you can shoot, if available proper experience and skills. Are you sure you'll die without extra glass? If not, better save your money and spend your time and energy on improving your skills.
Thank you for your attention!
Vasily A.
Post scriptum
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Focal length is usually described in millimeters (mm) and is the main parameter of a lens. This is not a measurement of the actual length of the lens, but a calculation of the optical distance from the point where the light rays converge to form a sharp image of the object on the digital focal plane sensor. The focal length of a lens is determined when it is focused at infinity.
Focal length tells you your angle of view, how much of the scene you can capture with it, and how large individual elements can be. The longer the focal length, the narrower the angle of view and the higher the magnification. The shorter the focal length, the wider the angle of view and the lower the magnification.
Fix vs zoom
There are two types of lenses - prime and zoom. Prime lenses have a fixed focal length, while zoom lenses have a variable focal length. The advantage of zoom lenses is their versatility. They are ideal when you photograph a variety of subjects, landscapes and portraits, and want one lens to cover everything. Using a zoom lens also reduces the likelihood that you will have to change lenses on your camera, which will save time and limit the possibility of dust getting on the lens or sensor.
The main advantages of fixes are their size and weight, as well as maximum value diaphragm. Prime lenses are generally more compact and lightweight than zoom lenses.
Prime lenses also have large aperture values (from f/1.4 to f/2.8), which gives an advantage when shooting in low light conditions, since this increases the ability to shoot objects handheld without “shaking” or out of focus caused by long exposures. Photographing with a prime lens with a large aperture also means you can have a shallow depth of field portrait photography and get a softer or blurred background (also known as bokeh).
Wide angle lenses are popular choice for shooting landscapes, interiors, photographs of large groups and when working in confined spaces.
Prime lenses in FX format, 50-60mm / in DX format 35mm
Standard lenses are popular because they depict reality close to how people see it. These lenses have minimal distortion, allowing you to show your subjects in the best possible light. They tend to use large apertures and absorb a lot of light, allowing for quick shots in low light conditions. Large apertures (f/1.8-f/1.4) also allow you to keep the image clear not only in focus, but also in the background. Standard lenses are also popular when shooting portraits in low light, when the photographer is unable to use flash or is looking to shoot the photo using available light.
Telephoto lenses FX format 70-200mm / DX format 55-200mm
70-200mm telephoto lenses are very popular for portrait and product photography, as well as nature and animal photography. They allow the photographer to get closer to the subject. When taking portraits, a telephoto lens allows the photographer to take a photo from a distance without invading the personal space of the person being photographed.
Super-telephoto lenses in FX format 300 - 600 mm/DX format 200-600 mm
These lenses have good range for sports and wildlife photography, photography where the photographer cannot get close to the subject.
Macro lenses: FX formats 60mm, 105mm, and 200mm/DX format 85mm
When shooting close-ups, a certain range of lenses is used that allow reproduction up to 1:1. These lenses allow the photographer to get very close to the subject and reproduce it at a 1:1 life-size ratio on the lens sensor. These lenses are popular when photographing subjects such as flowers, insects and small objects.
