Article text updated: 02/13/2019
In a photography lesson for beginner photographers on choosing camera settings, we saw a table showing the dependence of shutter speed, ISO and aperture on each other. In a comment to it, I explained that fast optics (that is, one that allows you to open the aperture as wide as possible) makes it possible to reduce the photosensitivity when shooting or significantly reduce the exposure time. However, again and again, in discussions of various nuances of photography on the site, the question arises of the advisability of using expensive fast zoom lenses for beginners. Let's try to dig deeper into this topic today and finally understand it.
For those guests of the blog who have not read the lesson on camera settings, I advise you to familiarize yourself with it first. Let me briefly remind you of the essence: the correct exposure of the image depends on the settings of the ISO sensitivity (ISO), exposure time (shutter speed) and the diameter of the hole in the lens (aperture). The same exposure value can be obtained by changing one of these three parameters separately. The shutter speed range and ISO values are the technical characteristics of a particular camera, the relative aperture values \u200b\u200bare a parameter determined by the lens design.
The aperture affects not only the amount of exposure, but also the degree of blurring of the background in the photo - the wider it is open, the closer the subject and the background from it (and also, the longer the focal length), the more the background is blurred. Therefore, the first advantage of a fast lens is the ability to greatly blur those objects that are behind our SVCC (story-important compositional center).
Aperture needed for bokeh
Fast optics (especially zooms) are expensive. It is widely believed among some photographers that it makes no sense to pay for it, and you can blur the background simply by using a longer focal length. To a certain extent, it is. If you open the bokeh simulator (the term means "blur", "fuzziness"), the link to which is posted in the lesson about shooting kittens (see above) and play with the settings, you will find that the same depth of field (depth of field) available on the insanely expensive Canon EF 85mm f/1.2L II USM portrait prime and the cheap Canon EF 70-300mm f/4.0-5.6 IS USM telephoto lens. For example, with a distance to the subject of 5 m and an aperture of f / 1.2 with a Canon 85mm f / 1.2 fix, you can get a depth of field equal to 15 cm. the maximum open aperture of f / 5.6, we get the same depth of field of 15 cm. True, the portrait will turn out to be large-faced, and not half-length ...
Shooting wide open can be difficult due to the shallow depth of field when photographing at close range. I encountered this, for example, when shooting kittens (see the lesson on blurring the background at the link above): they are small, you have to get close, there is not enough light in the room, opening a relative aperture leads to a decrease in depth of field - only the head is sharp. Therefore, I am ready to partly agree or, at least, not to argue with those amateur photographers who claim that there is no reason in expensive high-aperture optics.
Aperture is needed to shoot at low ISO with a short shutter speed
On the Nikon D5100 cropped DSLR, my main standard lens was the fast zoom Nikon 17-55mm f / 2.8G. When switching to a full frame Nikon D610, I bought a Nikon 24-70mm f / 2.8G ED AF-S Nikkor full-frame reportage lens for it. In the comments, some photographers noted that it would be better to take a cheaper, but dark zoom Nikon 24-120mm f / 4G ED VR AF-S Nikkor, because they have only one stop difference in aperture ratio. In response, I said that even this often gives me a noticeable advantage. Let's see why this is so.
The task of the photographer is to shoot at the lowest ISO value so that there is no digital noise that spoils the image.
I photographed the two frames above with the camera set to . The subject is still, so there was no need for a fast shutter speed. Everything changes if we do not have the opportunity to put the camera on a tripod: we must use the formula: B = 1 / FR for cameras that have a matrix with a small number of pixels like Nikon D7000 or B = 1 / (2 * FR) for multi-pixel sensors such as Nikon D7200.
The situation is even more aggravated if we photograph moving objects in poor lighting: we need an even shorter exposure time, which means we need to raise the ISO even higher.
For example, in the spring of 2016, my wife and I went on vacation to Turkey. , where I photographed a marble column with the head of Medusa Gorgon.
When photographing the subject with my fast Samyang 14mm f/2.8 aperture, I pushed the aperture to f/5.6 as I was afraid that I wouldn't get into the depth of field. Now I see that this was a mistake: at short focal lengths, the depth of field is large enough, and Medusa's face would have turned out sharp - you could open the aperture to f / 2.8. This would give me the opportunity to lower the ISO or shorten the shutter speed to 1/250 second, that is, the tourists would come out clear, not blurry (note: although, I think that blurry uncles here do not spoil, but rather improve the picture).
As you can see, for a full frame, the Nikon D610 ISO 25’600 ISO sensitivity is completely non-working. You can try converting the image to black and white.
Another way is to use noise reduction (noise reduction), but then we lose details: the picture becomes plasticine.
In order to better understand how an open aperture helps reduce ISO and speed up shutter speed, I suggest once again compiling a table that displays the relationship between these parameters. I take the camera, put it on a tripod and change the settings, writing down the values.
Note. The ISO settings usually display numbers in the natural range, extended ones are hidden behind abbreviations: L1.0 - 50, L0.7 - 64, L0.3 - 80 for parameters below ISO100, and for numbers above 6400 units - H0.3 - 8 ' 063, H0.7 – 10'159, H1.0 – 12'800, H2.0 – 25'600 units.
The numbers in this table do not need to be memorized: they change at every moment in time depending on the lighting of the scene that we are shooting. But you can analyze them. I propose to do this on the example of the picture that I received,
If instead of the fast aperture Nikon 35mm f / 1.4G I would use my reportage zoom Nikon 24-70mm f / 2.8, then at open f / 2.8 the aperture would differ by 6 stops (f / 1.4, f / 1.6, f / 1.8, f /2.0, f/2.2, f/2.5 and finally f/2.8). It follows from the table that in order to obtain the same time in an exposure of 1/100 second, ISO would have to be raised from 320 units to 1250. On cropped cameras, this value is the threshold for obtaining high-quality images. Full frame copes with high ISO better: up to 2900 for Nikon cameras and 2300 for Canon EOS cameras. Therefore, the Nikon 24-70mm f / 2.8 zoom would not spoil the picture.
Now, let's say that I decided to save money and instead of my expensive fast lens, I took a darker version of the Nikon 24-120 f/4.0. At open f / 4.0, the difference with aperture f / 1.4 is 9 steps - ISO needs to be raised from 320 to 2500 units - on the verge! Third option: take the cheapest whale lens for a full frame Nikon AF-S Nikkor 24-85 mm F 3.5-4.5G ED VR SWM IF Aspherical. He forces to set the already non-working ISO 3200.
And the last option is, say, a very dark ultra-long telephoto Sigma 150-600mm f / 5-6.3 DG OS HSM Sports Lens. The difference with the Nikon 35mm f / 1.4G is 13 stops, that is, to shoot this particular scene at f / 6.3, you need ISO 6400 units!
Such are the metamorphoses. Agree, the difference is stunning? But, probably, one of the photographers will say: “So in the open - the depth of field is too small. In practice, you will not be able to open the aperture to the maximum. And here I want to show a photo essay that I shot during a business trip to Germany on December 10, 2016. In the evening we went to the New Year's Fair in Frankfurt - there was no light at all, then we visited the Classic Remise Düsseldorf automobile museum in Dusseldorf and the famous Cathedral in Cologne, where the lighting was also not so hot. I had a full-frame Nikon D610 body with me and only a fast zoom Nikon 24-70mm f/2.8G. Here's what came out of it all.
Shooting a reportage with a fast zoom
So, we came to the fair when it was already dark outside. We shoot carousels - to come out sharply, you need a short shutter speed.
Here, of course, the aunt in the foreground did not hit the depth of field and ruined the frame. But when we shoot a scene where the CVCC is in the foreground (which is the majority), this problem does not arise.
Photo 10. High-aperture optics are not a problem for the photographer in frames where the main subject is in front. 1/1000, +0.67, 2.8, 3200, 56.
To shoot moving objects, we need to set a very fast shutter speed. Fast lenses make it possible to obtain a very short exposure time at a relatively low ISO. No wonder in English such glasses are called “fast lens”.
Of course, when shooting diverse scenes, you always need to remember the depth of field and analyze whether all important objects will enter the sharpness zone. Either business flat plots.
Photo 13. Shooting on an open aperture of a fast lens - always balancing on the verge of depth of field. 1/500, +0.33, 2.8, 3200, 45.
The following photo was taken at f / 2.8 at ISO 6400. According to table No. 6, when shooting with a dark travel zoom Nikon 28-300mm f / 3.5-5.6G ED VR AF-S Nikkor, at the short end at f / 3.5 will be H0 .7 (ISO 10'159). At long, at f / 5.6 - we would set H2.0 (ISO 25’600), and this would not be enough, the picture would turn out dark, that is, underexposed.
A couple more reportage shots demonstrating the fact that f/2.8 is not a problem, as long as our WHIS is in the foreground.
However, the bright zoom advantage of the Nikon 24-70mm f/2.8 is crucial if the photographer has the ability to shoot from far away. As you approach the subject, the depth of field decreases sharply and, despite the darkness, you have to clamp the aperture.
In order for the camera to enter the sharp zone, I had to reduce the focal length of my lens. But the plot is completely different.
Okay, the examples above were mostly written for extremely difficult lighting conditions. Let's look at the scenes shot indoors during the day.
Recently, I have been actively using the "Auto ISO Control" function on my Nikon D610 camera. In most cases, it works fine, but here it failed: I think that 1/40 of a second was enough for handheld shooting, which means the ISO would drop to 400 units.
When it comes to choosing lenses for crop or full frame, two approaches often collide: 1) one universal zoom (high-quality, but expensive) or 2) a set of cheaper primes. I can be classified as a fan of zooms - on this tour, another confirmation of this position was received: I would not have taken the following photo with a wide shot showing the viewer the scene of action if I did not have a Nikon 24-70mm f / 2.8 zoom. There was no way to take fixes with you on a trip.
The next few frames probably cannot be considered a good illustration for this article, because due to failures of the Auto-ISO functions, the shutter speed was too fast with an unreasonably high ISO. Although I was convinced that for some subjects ISO 6400 is not critical.
Photo 25. A trip to the automobile museum with high-aperture optics. If I hadn't trusted the automation, I could have easily lowered the ISO. 1/400, 5.6, 6400, 29.
Photo 27. The large size of the subject does not allow you to take advantage of high-aperture optics - the aperture is preloaded due to the small depth of field. 1/640, -1.0, 5.6, 6400, 24.
I want to show two identical pictures taken at different ISOs. Oddly enough, I don't see much of a difference. Well, maybe in the shadows the shot with ISO 100 is a little better.
We continue the journey. We visited the Frankfurt am Main Christmas market and the Classic Remise Düsseldorf car museum. Now fast forward to the glorious city of Cologne.
Photo 31. We shoot through the car window - it is clear that he focused not on the car, but on the building in the distance, which spoiled the frame. 1/100, -0.67, 5.6, 640, 70.
Of course, Cologne is famous for its Cathedral. , I said that you need to set a goal to visit all the buildings presented there, in reality. In addition to the Statue of Liberty in New York, Cologne Cathedral is the second tick.
We go inside the Cathedral. I don't know if you can use a tripod there, but I would like to, because the room is very dark. You have to take pictures with your hands, setting the maximum possible shutter speed for shooting without blurring. After processing, the photo looks pretty decent.
According to Table No. 6 “The ratio of shutter speed, aperture and ISO”, if I, at one time, had chosen a darker zoom Nikon 24-120 f / 4.0, I would have had to “pull up” the ISO to H1.
On an open aperture, my aperture glass even allowed me to photograph the stained glass windows of the Cologne Cathedral from my hands, without losing image quality.
When shooting with the Nikon 28-300mm dark travel zoom, you would have to set the ISO to 2500 (at f/ 5.6)
I can’t think of anything to comment on the rest of the pictures from the tour of Cologne Cathedral, just look at the difference when shooting in a dark room and on the street.
Across the road from the Cathedral is a brasserie. It was a sin not to come here so as not to taste a glass or two of Cologne Kölsch. Another test for my fast Nikon 24-70mm f/2.8 reporter.
Photo 39
Such a long way I found to show off my trip in a rented car in Germany. Joke! Seriously, the examples of pictures in today's report, in my opinion, show that the Nikon D610 full-frame camera has a working ISO of up to 5600 units, at 6400 we already get "plasticine". Well, a fast lens is a good help for taking photos in low light conditions.
Since I have pictures with a New Year's mood, I will take this opportunity to congratulate you, friends. I wish that everything will be wonderful in your families next year, your hobby will not ruin the family budget (which is difficult to ensure, since high-aperture optics cost money), and also please you and your loved ones. Happy New Year my friends!
P.S. I hope this article will help beginners understand how to get great Christmas shots. There are two ways out: either run to the store for fast optics, or for an external flash, which will allow you to get a short shutter speed even with a dark lens.
Photo or video recording is a stream of light fixed on a light-sensitive surface (in the case of digital technology, on a matrix), passing through the lens. Optics in shooting plays a paramount role and its quality largely determines the quality of the future image.
Any lens consists of several lenses combined into groups. Each of them has its own function. The lenses refract light, focusing it on the matrix, and protect it from distortion, reflections and other negative optical effects. Passing through these "barriers" the luminous flux naturally weakens. As a result, the light that hits the matrix becomes less bright, dims.
There are many ways to help avoid "light loss", of which the most effective is the use of coated lenses, passing through which the light will lose a minimum of its intensity. So, the ability of a lens to transmit the greatest amount of light without loss of intensity is called aperture ratio.
How to determine aperture
Aperture is a complex concept and manufacturers express its value using digital coefficients. So, the simplest, inexpensive zoom lenses of modern cameras have aperture ratios from 3.5 to 5.6 units. The lower the coefficient value, the higher the aperture ratio of the lens. The Carl Zeiss Planar 50mm f / 0.7 lens, designed for filming in . High-aperture lenses for filming have a range of 0.7 to 2.8 units.
The Carl Zeiss Planar 50mm f/0.7 lens was used to photograph the far side of the moon.
How aperture affects image quality
Aperture determines not only the intensity of the light flux, which allows you to shoot with short shutter speeds in very low light. It is also related to the diameter of the relative aperture of the diaphragm. The higher the aperture ratio, the wider the relative aperture, and hence the smaller the depth. This is especially important in portrait photography, as this lens can bring out objects in the foreground and blur the background.
Lenses with a fixed focal length have the highest aperture.
That is why aperture is the most important characteristic for portrait lenses and any professional portrait photographer has fast optics in his arsenal.
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, what is it? This is the ability to pass light through itself, the more light it passes through, the brighter the image will turn out, the more light it will have. There is a concept of geometric aperture, we omit formulas and calculations, we only note that the ratio of the diameter of the maximum open aperture of the lens to the focal length is the aperture.
Manufacturers mark the received figures on their devices. It looks like this: f / 3.5-5.6, here the aperture ratio is variable. There are models with a constant value, in which the focal length is also constant.
Values for each lens range from 0.7 to 16 (based on the world's known existence), where 0.7 is the world's fastest lens, a limited edition made especially for NASA's dark side of the moon. At the same time, in the indicated line, the next value will reduce or increase the amount of light that will pass through 2 times.
Whale optics for the most part has a value of 3.5-5.6, which also affects its inexpensive cost. The higher the value, respectively, the more expensive the optics. The highest cost are those with a large variable focal length, since they are technically the most complex.
However, buying a particularly fast aperture with a value of 1.2 does not make any sense without proper necessity, especially if you mainly shoot outdoors in good light, you will rarely use this option and spend money completely pointlessly. Aperture makes it possible to obtain high-quality images in low light conditions.
What is a fast lens for?
If you're shooting outdoors in good daylight, or in a well-lit studio, and widening your aperture to f/1.2 or 1.4, there's a good chance you'll ruin your shot. In this case, the subject you are shooting will not be in focus, and the image will lose a lot of depth of field.
Once again, we recall that the maximum aperture should be opened only in order to capture more light, which is not enough. As a rule, in the studio, and even more so when shooting in daylight, it is more than enough.
When choosing for yourself, think about the tasks that you set for him. For a beginner, and sometimes for more advanced ones, the main thing is not to fall into the trap of the "hamster" principle, when both of them can be done without bread.
Well, you won’t be able to buy optics that simultaneously meets all your Wishlist! So that at once both telephoto and wide-angle, and an excellent portrait lens, and so that macro and micro in excellent quality, and the aperture of all spectra, and please, inexpensive. This does not happen, it is necessary to determine and set specific tasks.
For portrait shooting, the option with a fixed focal length and aperture is perfect, some fifty dollars for these purposes is the very thing. For shooting outdoors, beautiful and complex landscapes, sports, a telephoto telephoto lens will be the best assistant.
They come with different values, it is worth choosing the one that meets your requirements, and this is not necessarily with a value of 1.2, because in daylight, using the aperture in the open position, I repeat, you will simply ruin the frame.
Having figured out for yourself what lens aperture you need, what it is and how to effectively use the capabilities of your existing lens, you can go for a new, more powerful one, or maybe vice versa. The main thing to remember is what you need to get the highest quality pictures.
Where is it used in optics?
I hope it became clearer to you how lens aperture is used, what is it? Now we can talk about where in general it is used in optics and for what purpose. Now you can easily answer this question yourself.
All lenses used by mankind have their own aperture, whether they are professional or amateur cameras, or home telescopes, as well as. In telescopes for independent observations of celestial bodies, the luminosity is not so important.
But for filming in space, it is of great importance, as in a camera, the image quality will depend on how much light the optical system of the space traveler will gather.
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, unlike 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 different cameras are compared using it, 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.
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