Lens aperture: what is it and what is its use? Ten of the fastest lenses What does lens aperture mean.

Everyone wants to get beautiful bright pictures when they take pictures. However, very often it turns out that when you see an interesting moment, you manage to capture it, but the photo turns out to be somehow dark. A lens with a low aperture may be to blame for this. That's why it's so important to know what it means. Let's figure it out.

The aperture ratio of the lens is another very significant parameter. It is just as important as the angle of view and others. This parameter characterizes the brightness of the image built on the lens matrix. The faster the lens, the brighter the image it creates. And with a smaller indicator, it will be darker.

Aperture is characterized by the relative value of the size of the hole, and is indicated in the form of a fraction. For example, the inscription ¼ means that for a lens with a relative aperture size of ¼, the aperture diameter is four times smaller than the focal length parameter. It is important to note that the size of the actual objective aperture is rather a virtual value. This diameter usually does not match either the diameter of the diaphragm or the front

It is quite possible to calculate the size of the actual objective hole, but it cannot be measured. Traditionally, relative values ​​are dependent on the size of the image field for which the device is designed. It can be said that lenses with a fixed focal length have a very high aperture, for example, f / 1.4-f / 1.8, in contrast to those in which the focal length is variable. Usually, for optics with a variable focal length, the aperture parameter is also variable, since their design is much simpler.

If we talk about this, based on some example, then we can say that if the optics are marked 20-80 / 3.4-4.7, this will mean that with a focal length of 20 millimeters, the relative size of the hole will be f / 3.4, and if the focal length becomes 80 mm, then the aperture will change and become f / 4.7. However, the higher the lens aperture, the more expensive the device itself.

It would be ideal to have in your arsenal a set with a different indicator of this parameter, however, this option is not suitable for ordinary people, since spending on them is incommensurable with anything. It makes sense to acquire such expensive equipment only if the photos will be printed in magazines or somewhere else, otherwise not.

In the absence of such a goal, it is quite enough to purchase an ordinary camera. You should not take cameras with a low aperture ratio, since very soon you yourself will feel that the photos are not beautiful and bright enough, and this defect cannot be removed. However, modern devices, even the simplest ones, have very high-quality built-in automation.

At its core, lens aperture is a property that shows the amount of light passing through this device. Based on this situation, lenses that allow only a small aperture have the smallest aperture. Lenses can be slow or fast, that is, having a larger or smaller aperture, depending on the size of the aperture, usually it is used to compare different cameras whose focal length is the same.

According to such a parameter as lens aperture, different types of photographic equipment are most often compared. It is believed that at the maximum value of this indicator, the best pictures are obtained in various degrees of illumination. If used, then you have the opportunity not only to change the focal length, but also to get a different aperture ratio.

If you've been into photography at least a little, if you've bought a new camera or lens, you've most likely heard of the aperture ratio of optics. The fact is that aperture is a very important criterion for any lens. When buying a lens, it is the aperture ratio that usually pays special attention. Almost any salesperson in a store will “push” a fast lens to a naive beginner. And only because sufficiently fast lenses are more expensive than those whose aperture ratio is not very good. In addition, many people naively believe that aperture can solve all the problems that a photographer has in the process of his work.

That's what we decided to talk about aperture ratio with you in our today's article.

To begin with, let's figure out what all the same it is - aperture. If you explain popularly, as they say, “on the fingers”, then the aperture ratio is the ability of the lens to transmit light. Aperture shows the maximum possible amount of light a particular lens transmits to a digital camera matrix or film. The larger the lens aperture, the more light passes through the lens. Therefore, the greater the lens aperture, the more opportunities to take high-quality photographs in low light conditions, without using additional light sources, such as a flash, as well as a tripod for shooting at slow shutter speeds.

What determines the aperture ratio of a lens? And it depends, first of all, on these parameters:

• Diaphragm
• Focal length
• Optics quality

Today we do not see the point in delving into the theory of physics (if you are still interested, open the textbook). We'll just say that the aperture ratio of a lens is the ratio of the diameter of the aperture's widest opening to the focal length. It is this ratio that is indicated on the frame of lenses by their manufacturers. Most likely, you paid attention to such numbers on your lens: 1: 1.2, 1: 1.4, 1: 1.8 1: 2.8, 1: 5.6 and the like. The larger this ratio, the greater the aperture ratio of the lens. Fast lenses include lenses with this indicator of 1:2.8, 1:1.8, 1:1.4 and more.

For general interest, it can be said that the lens, which is considered the fastest in the world, was made in 1966 for NASA and was used to photograph the dark side of the moon. This lens was called Carl Zeiss Planar 50mm f/0.7. Its aperture was equal to 1: 0.7. This lens was made in only ten copies.

Even a novice photographer, not to mention professionals, probably knows that the fastest lenses are portrait lenses that have a fixed focal length (for brevity, lenses with a fixed focal length are usually called primes in the language of professionals). Every photographer who considers himself a master of photography should have such a lens. Such fast fixes have one indisputable advantage. And it is very significant. This advantage lies in the fact that fast fixes are quite affordable at their cost. And, besides, if you compare them with fast zooms - fixes are sometimes even better than them and are able to create a very wonderful picture.

Lenses with good aperture are great for shooting portraits, as they give a fairly shallow depth of field. And this, as you know, is very important for portrait shooting.

What is the best portrait lens for the job? With aperture 1: 1.2, 1: 1.4 or 1: 1.8?

As we said today, beginners in photography usually try to get a faster lens. And sellers willingly offer them such lenses, because they are very expensive, and this, of course, is very beneficial for the store. But this is where the question arises: is it necessary to overpay for a lens with an f / 1.4 aperture, if in real practice you are unlikely to use it?

The depth of field in the picture depends directly on the aperture of the lens you are shooting with. That's why when shooting at f/1.2, f/1.4, and f/1.8, the plane of focus is quite small. In this case, there is a very high risk that not the entire subject will fall into this plane. Here, for example, as in this picture.

Its author believes that he spoiled this shot. He shot it with a wide open aperture of f / 1.2. And that is why I did not get into focus, and the picture turned out to be blurry. But this picture was taken by him, but already with an aperture of f / 2.8. As you can see, the photo turned out quite well: both the background is blurred and the model's face is shown sharply.

In general, f/1.2 should only be used in the most exceptional cases. For example, in case of a real lack of light for shooting. And even that doesn't always help. It is often easier to simply increase the ISO sensitivity (raise the ISO value). This is especially true if you are working with a full-frame camera. Even when shooting with a 50mm prime lens. at f/2.8, it's easy to miss out on sharpness. And then some details of the photographed object in the picture will be blurry. Therefore, we always recommend in this case to play it safe and shoot in good light at an aperture of at least f / 3.2.

Well, in conclusion of our article, let's briefly summarize what was said in it.

So, fast lenses with a fixed focal length are ideal for shooting portraits. It is for this reason that we strongly recommend that every photographer have such a lens.

When you buy a fast lens, do not succumb to the persuasion of sellers and the declared aperture of 1:1.2 or 1:1.4. You will hardly have to shoot at such an aperture. And if you have to, then very, very rarely. That's why, if you still have a choice between a lens with aperture ratio of 1:1.2, 1:1.4 and 1:1.8 - do not waste your money on buying something that you absolutely do not need. In practical work, a lens with an aperture ratio of 1: 1.8 is quite enough.

In simple terms, the aperture of a camera is a device through which light enters the camera's matrix. The diaphragm consists of the so-called "petals", the number of which can vary from three to twenty pieces. Depending on the intensity of illumination, the petals reduce or increase the diameter of the light-transmitting hole. The principle of their action is similar to the pupil: in dim light it expands, in bright light it narrows.

To better understand the principles of calculating the characteristics of a lens (including the aperture value), it is necessary to know what the focal length of a lens is.

Lens focal length

Focal length- this is the distance between the camera matrix and the main optical plane of the lens, subject to its focusing to infinity. This indicator determines the viewing angle achieved by a particular lens. The longer the focal length, the smaller the viewing angle. The specifications usually indicate the minimum and maximum focal length that the lens provides. It is customary to measure it in millimeters.

The ratio of the focal length to the aperture size is called the f-number. That is what determines the aperture value. The smaller this indicator, the larger the hole, and the more light penetrates the camera matrix. It is worth considering that the aperture value is often indicated as a denominator of a fraction, without specifying the focal length.

Possible values ​​of f-numbers are described by a special aperture scale, which is a sequence of numbers:

1 - 1.4 - 2 - 2.8 - 4 - 5.6 - 8 - 11 - 16 - 22 and so on.

The essence of the scale is that narrowing the aperture of the lens by half leads to a decrease in the amount of light entering the matrix by four times. A similar effect has a double increase in focal length. The aperture scale is often applied to the lens barrel for the convenience of the photographer.

Lenses with the smallest f-numbers (f/1.2 - f/1.8) transmit the maximum amount of light. Such lenses are called fast lenses.

Lens aperture

Aperture- this is the degree of attenuation of the light flux by the camera lens, or, in other words, the ability of the lens to transmit the real brightness of the object. The larger the aperture, the better the pictures taken in poor lighting conditions without using a tripod and flash are obtained. In addition, fast lenses allow you to take pictures with the shortest possible shutter speeds.

The aperture value is determined by the value of the maximum open aperture. Together with the focal length, it is usually indicated on the rim of the lens. So, for example, the inscription 7-21 / 2.0-2.8 means that with a focal length of 7 millimeters, the aperture ratio is 2.0. Accordingly, with a focal length of 21 millimeters - 2.8.

When choosing a lens, it should be borne in mind that the maximum open aperture is used very rarely. At the same time, the price of fast lenses is significantly higher. For most buyers, there is no point in overpaying for an indicator of 1: 1.2; it is quite enough to buy a more budget option with an aperture ratio of 1: 1.8.

Relative hole

The reciprocal of the f-number is called relative bore. The relative aperture value determines how many times the focal length of the lens exceeds the diameter of its aperture. On the lens barrel, this indicator usually looks like a 1: 2 fraction. Such figures mean that the hole diameter is half the focal length.

In different sources, the concepts of the value of aperture ratio, the size of the relative aperture and the diaphragm itself are often described in a scientific, incomprehensible language. In order not to make a mistake when choosing a camera and not get confused in the characteristics of the lens, it is worth remembering the dependencies that exist between them.

So, luminosity is a constant property of optics that cannot be changed or adjusted. It should be remembered that aperture has nothing to do with the current aperture value. As mentioned above, its value is equal to the value of the aperture in the maximum open position.

The relative aperture, unlike aperture, is a variable value. You can adjust it with the aperture.

Lens aperture- this is one of the main parameters that you should pay attention to when choosing a lens (along with ). The luminosity of the optical system shows the degree of attenuation of the light flux. In other words, the luminosity shows how much of the light flux the lens system of the objective is able to pass through.

The fact is that part of the light flux passing through the lens is scattered and reflected from the lenses, part of the light is absorbed by the material from which the lenses are made (glass, optical plastic). Therefore, the luminous flux is attenuated by these purely physical characteristics.

So, by buying a lens with a larger aperture, you will be able to open the aperture more. This means that you will be able to let in more light (it becomes possible to shoot in low light). Also, the more the aperture is opened, the smaller the depth of field in the frame is (the objects that are not in the focus area are more blurred). That is why f1.4-f2.8 lenses are considered good portrait lenses.

You may notice that manufacturers of photo optics produce a line of lenses with the same focal length, but different aperture ratios. Moreover, the greater the aperture ratio, the more expensive the lens costs, and the increase in cost is significant. For example, let's compare the prices of Canon lenses with a focal length of 50 mm. So, a 50 mm 1.8 lens costs 3,500-4,000 rubles, a 50 mm 1.4 lens costs about 13,500 rubles, and a 50 mm lens with aperture ratio of 1.2 is sold at a price of almost 48,000 rubles. Data are current as of February 2013.

As we found out, in most cases the larger the aperture of the lens, the better, because:

— you can shoot in the worst lighting conditions;

- you can shoot with a smaller depth of field.

On the other hand, you need to pay a lot of money for additional aperture. Therefore, when choosing a lens, weigh the pros and cons.

Choose your lens wisely and enjoy your shots!

What is written on the lens?

Please look at this lens - what do the numbers on the lens barrel mean?

Aperture of a lens is the aperture value of a lens when it is fully open.

For the lens in the photo just above, the lens aperture is 2.6. And than less number, topics lens aperture more. Paradox?

There is no paradox here ... when we say MAXIMUM DIAPHRAGM, it means that it is completely open and we mean the size of the aperture hole, and not its designation with a number. And the number indicating the aperture at its maximum opening will be minimal because in reality it is the denominator of a natural fraction (if you notice, 1: 2.8 is written on the lens barrel - these two points are a mathematical division sign, often there is so little space on the frame, that the division sign and the unit are simply not written

Why is lens aperture important when choosing a camera?

When choosing a camera with a removable (=interchangeable) lens, you can buy a fast lens and replace the one you already have. But if you are going to buy a camera with a fixed lens (for example, a compact camera), it is very important to find a suitable model of a camera with a fast lens - with an aperture of no worse than 2.8. Because the more the lens aperture opens, the more freedom you will have, the freer you will feel in non-standard lighting conditions.

In addition, the depth of field depends on the aperture of the lens. In turn, depends on your photos.

Many compact cameras have a very limited choice of apertures, and as a result, a large depth of field. Moreover, some super-compact models of digital cameras and almost all cameras do not have smartphones and phones - in such cameras, instead of the classic diaphragm (an adjustable hole in the partition between the lens lenses), a special filter is used, the transparency of which is regulated by the camera electronics. With such a camera, it is generally impossible to influence the depth of field. I'm not going to say it's good or bad. It all depends on

If you don't want to "bother" with the camera settings and you like to just point the camera at the subject and press the shutter button - you won't even notice the difference. If you like to experiment a lot, shooting in different, often not ideal, lighting conditions, 2 or 3 apertures available can severely limit your options.