The diaphragm is simple. In a nutshell, aperture is a device in the lens that measures the amount of light.
Aperture device in the lens Nikon Nikkor 105mm 1: 1.8 (AI-S)
For a better understanding of the operation of such a device, I will give an example from life. When people look at the sun, they squint their eyes, that is, they reduce the gap through which light passes. If people did not squint, the sun would burn the retina with its strong light. At night, you need to do the opposite - open your eyes wider to capture more light, while the pupils also dilate. Eyes with large pupils have many animals that need to see well at night.
Often the diaphragm is also called 'luminous efficiency ' or 'aperture' or 'relative hole' or 'number F'. These concepts are strongly related to each other and are synonymous for many photographers. But among them there are small differences, described below.
Lens aperture Is the ratio of the effective aperture of the lens to the focal length of the lens. The reciprocal of the relative aperture is called f-number or aperture number.
The relative aperture of the lens is expressed numerically by ratio or fraction. For example, take a lens that has a relative aperture 16 times smaller than its focal length; as a result, the relative aperture can be numerically written in the following ways: 1:16 or f1 / 16 or f = 1: 16 or F 1:16, etc. d. There is no particular difference in the recording, and every photographer will always understand what is at stake.
If we take the number opposite to the relative aperture, then we get the number of aperture. Usually it is by this number that photographers directly understand the general term 'aperture'... If we take the same lens, which has a relative aperture 16 times smaller than its focal length, then its aperture number will be equal to 16. And numerically it can be written in the following ways: F16, F / 16, 16 (such a 'bare' number aperture is indicated on the lens barrel). There is no particular difference in recording.
Some lenses have an aperture ring on their body. There is usually a marking on the ring, consisting solely of aperture numbers (shown in the figure below). Almost all modern lenses do not have such a ring, and the diaphragm is controlled by the electronics and camera controls.
Lens aperture control Nikon ED AF Nikkor 80-200mm 1: 2.8D (MKII). Using the ring you can set the values F / 2.8, F / 4, F / 5.6, F / 8, F / 11, F / 16, F / 22.
Usually the concept of 'aperture' and 'aperture' are synonymous, but in fact there is a certain sacristy between them. So, the diaphragm is only responsible for geometric aperture (the ratio of linear geometric indicators). And not only the aperture is responsible for the overall 'real aperture' of the lens, but also many other factors: the optical design of the lens, the percentage of light reflection and transmission by the lens, the drop in the aperture number when focusing at different distances, the percentage of light absorption by the photo filter, etc. More details about the difference between the concepts of 'aperture' and 'aperture' can be found in the section about 'T-feet'.
The aperture is sometimes also called the 'Lens Aperture' (Latin 'Apertura' - 'Hole'). Therefore, on many cameras, the metering mode exposure с aperture priority called 'A' or 'AV'-'Aperture Value '-' Aperture Value '. Details about this mode are described in the section 'P, A (AV), S (TV), M'.
Please note that the magnitude of the front lens of the lens and, in fact, the magnitude of the front light filter have no direct relation to the aperture ratio of the lens. Different lenses with the same focal length and the same maximum aperture can have completely different diameters for their front lenses. For example, take two class 50 mm F / 1.4 lenses: Nikon AF Nikkor 50mm 1: 1.4D и Sigma 50mm 1: 1.4 DG HSM EX... The first has a tiny filter diameter - 52 mm, the second has a huge one - 77 mm. But their aperture (practically - maximum aperture) will be the same.
What is the diaphragm?
By the mechanical part of the diaphragm device is understood a changing circular hole in the lens. Typically, the hole opens and closes with the petals. In this case, the petals are called diaphragm blades, and the diaphragm itself is 'iris' (from the English 'iris' - 'iris'). The number and roundness of the aperture blades determines how much the hole will be formed round. The stronger the rounding of the diaphragm opening, the better. Professionals often refer to the diaphragm simply as'hole'since it is real, a kind of hole that changes its size and doses the amount of light.
What the diaphragm affects:
- The amount of light that the lens can let through over time.
- To control the depth of sharply depicted space (GRIP)
- The brightness of the image in the optical viewfinder
- On image quality, especially on its sharpness, aberration, vignetting, bokeh and various visual effects.
IMF impact
As it turned out, the aperture affects not only the amount of light, but also the depth of field. The smaller the number F, the smaller the depth of field. The larger the F number, the greater the depth of field. This is one of the main techniques in photography to control the point of attention in the photo. It is very important to be able to manage GRIP for portraits where you need to focus on a person. Macro photographers are well aware what is DOF, they have to shoot on very tightly closed apertures to increase the depth of field. In general, where write about DOFwrite about blurred background. You can read the best way to take pictures with a blurry background in my article - Taking Pictures with Blurred Background.
Blurring the background at different apertures
Depth of field preview
Typically, modern cameras have the ability to focus with a fully open aperture. When a picture is taken, the camera’s automation closes the iris to the set value. To see how the images will look when the aperture is closed, you can sometimes use the aperture repeater. This allows you to look into the viewfinder (optical or electronic) without a picture how the picture will look when the camera closes the iris. You can read more about depth of field preview.
Aperture for picture enhancement
Aperture is understood to mean simply changing the aperture value. Using aperture control, you can achieve a sharper image from the lens. Basically, the sharpest image is achieved somewhere at the average aperture of a lens. At their largest aperture, lenses suffer from chromatic aberrations and vignetting. When closing the diaphragm HA and vignetting practically disappears. At very small apertures, lenses suffer from diffraction loss of sharpness. Also, when you close (decrease the aperture), not only the sharpness increases, but also the contrast of the picture. A large aperture allows sighting through the optical viewfinder without any problems, since the lens gives a lot of light and the entire frame is clearly visible through the peephole. You can only view with an aperture below F5.6 through the optical viewfinder in good lighting conditions. Also, pictures with a larger aperture can appear brighter and more saturated - this effect is associated with smoother transitions in pictures from dark to light areas.
Bokeh and aperture connected forever
Aperture greatly affects the bokeh pattern. Usually the best bokeh for the lens is achieved at the maximum open aperture. In this case, the physical hole itself is as round as possible. When closing the diaphragm, the diaphragm petals instead of a circle form different polyhedrons. These polyhedra are clearly visible in the blur zone. Very often such polyhedra are called nuts, washers and circular saws.
Since in cheap lenses there is a small number of aperture blades, usually no more than 5-6, then in the blur zone figures appear exactly like “nuts”. Those lenses that on closed apertures give the correct round luminous spots in the blur zone, for example, can be attributed to them. Nikon AF DC-Nikkor 105mm 1: 2 D Defocus Image Control or Tair-11A 2,8 / 135. In new lenses, it is very rare to find a large number of aperture blades, but now they make more rounded blades, which, even with a small number of them, give a round hole.
Below are my photographs taken with different cameras and lenses and taken at different values of the number F. Shooting options (EXIF) for each photo are indicated in the bottom line.
Aperture in phone cameras and other small devices
The diaphragm is a mechanical part of the lens, it cannot be done programmatically. Almost all phones lack a physical diaphragm device. Many 'soap dishes' also lack a diaphragm. How to be? Usually the camera in such devices doses the amount of light only shutter speed and a variation of the ISO value, and the aperture value itself is constantly fixed at the maximum value. For example, on my Nokia 7610 it is indicated that F2.8, because the camera always shoots at F2.8.
How to adjust the aperture in the camera?
In cameras, it is responsible for the diaphragm F number (aperture number)... It shows how many times the diameter of the relative aperture is less than the focal length of the lens, on the lens it is written as f1 / 1.4 or f1 / 5.6, sometimes you can find the spelling f = 1: 6.3 or 1: 5.6, or f / 16, f / 3.2. Often, lenses or cameras only have one f-number, such as' 1.4 'or '16.0 .8.0'. Usually, the aperture number is written with a large letter 'F' without fractions, for example, F 1, and the relative aperture is more often written through a small letter 'f', for example f 11:XNUMX (there can be any spellings). The easiest way to adjust the aperture is by putting the camera in aperture priority mode. On the main control wheel of the camera, or in the menu of the camera, this mode is indicated by 'A' or 'AV'. To make it easy to remember, you can simply say: Aperture means you need to turn on the 'A' mode. Details about the creative aperture priority mode are written here.
'Light' and 'dark', 'fast' and 'slow' lenses
The maximum aperture value determines how much the lens can be used in poor lighting conditions. Lenses with a large aperture are called 'bright' or 'bright', usually an F value should be below 2.8. That is, lenses with maximum apertures F1.4, F1.8, F2.0, F2.2, F2.5, F2.8 are called fast or just bright. Everything below F1.4 is called super fast. Super fast lenses include Nikon 50mm f / 1.2 AI-S Nikkor or Canon Lens FD 55mm f / 1.2 SSC. Lenses that have an aperture value of F / 2.8 to F / 5.6 are called ordinary. medium-aperture lenses, these lenses can be attributed Nikon 24-85mm f / 2.8-4DAFIF Nikkor or Nikon 300mm f / 4.5 Nikkor-H Nippon Kogaku Japan Auto Non-AI. Lenses with a maximum aperture less than F / 5.6 are called low-aperture or 'dark'. These lenses include MS MTO-11 1000mm F10.0. By the way, it is very difficult to make a fast zoom, in more detail here.
Different holes for different values of the number F
Since aperture affects speed excerpts, then the lenses are still divided into fast and slow. A fast lens means that you can use it to shoot an image with a short shutter speed (with 'fast' shutter speed). And under slow, that it can be used to take a photo with a long ('slow' shutter speed). If you fix the ISO value, it depends on the aperture excerpt, and the brighter the lens, the faster it is. And the darker the lens, the slower it is.
The difference in aperture ratio
The difference in aperture and other photographic variables is usually measured in feet. When changing the aperture by one stop excerpt will change in twice... Also, if you change the aperture by one stop, you can change the ISO by two instead of the shutter speed. It is very important to note that the difference in aperture values is not linear, but quadratic. Take two apertures F / 5.6 and F / 2.8, it would seem that the difference in geometric aperture is 5.6 / 2.8 = 2 times, but this is not true. On aperture affects the area of the circle formed by the diaphragm, and not its diameter. The number F is associated only with the diameter. To calculate the difference in area you need to take the squares of the diameters. Therefore, it turns out that the difference in aperture ratio between F / 5.6 and F / 2.8 is (5,6 * 5,6) / (2,8 * 2,8) = 4 times. Here is such a trick. How to remember this? There are two ways out, either by dividing the squares of the F numbers, or by first dividing the F numbers and then squaring the result. Why am I bored with calculations - but because often amateur photographers have no idea how many times one lens is 'lighter' or 'darker' than another lens.
Also, experienced photographers know about the so-called aperture series of numbers, in which every two adjacent numbers F differ by one stop.
A number of numbers F: 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 46, etc.
Golden Rule:
Aperture and shutter speed are bound by the golden rule. To keep correct exposure with the same ISO, you must either close the aperture and increase the shutter speed, or, conversely, open the aperture and reduce the shutter speed.
Close, open, increase decrease - no need to be confused
Everything is very simple. Closing or decreasing the aperture means increasing the F number. The aperture was F2.8, when it was closed, it became F5.6, it was closed even stronger, it became F16.0, etc. For example, there is the phrase 'covered the hole by two stops', it is deciphered as follows: 'made the number F large and reduced the area of the hole by 4 times'. The main thing is not to get confused, when the aperture opens, the F number decreases. And when the diaphragm closes, the F-number increases. For example, the aperture was F32.0, when it was opened, it became F8.0, when it was opened even stronger, it became F5.6.
What to do - nothing is clear
If you have a DSLR, turn the camera backwards so that you are looking into the lens, press the shutter button (take a picture) and you will see the hole in the lens close and open - this is how the aperture works. If you peered into your lens and did not see anything, then below is a slow-motion video, where you can clearly see how the aperture works during shooting. In the video, the petals close to F / 16 and form a very 'small hole':
- The method of operation of the device aperture on Nikon digital SLR cameras and its effect on video recording
- Nikon 'E' Lenses with Electromagnetic Iris Control
- An interesting aperture on Nikon digital SLR cameras
- G-type and Non-G type lenses (with aperture ring and without aperture ring)
- Work with old Nikon lenses such as AI, AI-S, NON-AI, PRE-AI, AI-Converted, which transmit or do not transmit aperture value to the camera
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Conclusions
Diaphragm Is a luminous flux dispenser that affects exposure, GRIP, brightness of the optical viewfinder and image quality. In general, if you don’t shoot at different values of the number F, you don’t really know what it is :)
Material prepared Arkady Shapoval. Training/Consultations | Youtube | Facebook | Instagram | Twitter | Telegram
Interestingly, but there is somewhere a diaphragm such as on Stargate :))) of those in the first picture :)))
They saw through, on the poster, the diaphragm from the Stargate. I wonder if there is a lens with a front lens of 7-8 meters, like on the gate :)
Probably there is no 7 metro, but the biggest one I think is at Hubble. And although officially it’s a telescope, the principle of operation and purpose is just like a regular camera :)
And I have a question for you, tell me please, for some reason the aperture on my Af 50mm 1.8D is always slightly closed to a value of 2 (this is if you close the rear lever near the bayonet on a digit or manually), although the camera correctly displays a value of 1.8.
If you switch the lens to the manual aperture control mode (as on film cameras), then everything falls into place and 1.8 is really 1.8. Is it “so conceived” or carried to the service?
Hubl also knows how to expose the same thing for several days. Regarding fifty dollars, there is no such Effect on mine, but I met with this often. Check the histogram, if the camera has the same histogram at 1.8 and 2 in manual mode at the same shutter speed, then you need to carry it. If not and 1.8 lighter, then you can live with this problem.
exactly
well, they lied in size :))) I mean in shape :)) it’s a very cool shape in the diaphragm :)))
powerful cat, pumped up
Thank you for the article! often you have to explain what the shutter speed and aperture are, you very clearly painted everything.
I wanted to clarify - in some of the photos in the articles, the shooting parameters are somehow - iso800 and the shutter speed is 1/640. Why such a fast shutter speed and such a high sensitivity? Wouldn't it be more correct to lower the ISO and shorten the shutter speed for a better image quality (noise, etc.)? After all, with such a plot, and 1/125 would, IMHO, be enough? Thanks!
Photos for the article were taken in low light conditions, when light sources do not get into the frame. Without light sources, the shutter speed drops several steps at once and you have to shoot at high ISO. When light enters the frame, the shutter speed becomes very short. It is treated using Auto ISO, but I do not trust him.
that is, changing exposure you need to change and iso? if not in auto mode?
Rather not “necessary”, but “desirable” if you need a noiseless shot, but this recommendation applies precisely to very difficult shooting conditions.
Arkady, thanks for the site! Everything is very open and clear. I wish you success!
I, as a newbie, got confused several times already read the article and comments, but I still see contradictions in the text.
1) At the highest aperture value, lenses suffer from chromatic aberration and vignetting. - means the diaphragm is open (the number of eff is small) - ok
2) When the aperture is closed, CA and vignetting practically disappear. - means diaph. closed (the number of eff is large - ok
3) At very small apertures, lenses suffer from diffraction loss of sharpness. - means diaph. Closed (large number of eff) - ok
4) Also, when you close (decrease aperture), not only the sharpness increases, but also the contrast of the picture. - means the daphragma is closed (the number of eff is large) - ok
QUESTION: 3 and 4 sentences contradict each other? Is this a mistake in the presentation or am I misunderstanding something? Maybe there the word goes down, not go up? Since it’s logical to have less light, less contrast!
Thanks for the answer
Each lens has its own values on which it is as sharp as possible, as a rule it is from 5.6 to 13. Over 13, diffraction most often begins. Therefore, it is not recommended to close the diaphragm minimally. When shooting for example portraits on open from 1.4 to 2.8 climb HA. The better the lens, the better it resists HA to defeat which no one was able to completely. Some advise shooting at aperture value of 8 only then you will be left without portraits. At open values, the sharpness drops due to XA, at strongly closed ones due to diffraction
Ordinary Putin's due to the fact that the larger the F number, the smaller the aperture value (closed aperture). Tracing logic is not difficult.
3-4 everything is simple. For example, in the general form, for a 50 mm fix, the sharpness of the picture increases when the aperture is closed from 2 to 11, and after 11 or even 16, the sharpness drops due to diffraction
> The wider the aperture is open, the more vivid and vivid the colors.
Why such a conclusion? ..
On many lenses the exact opposite is true! A completely open diaphragm leads to a drop in contrast and, accordingly, the colors are faded.
> People, who often buy a digital SLR camera with a whale lens, ask themselves the question "why photographs are almost no different from photographs on a soap dish." The answer is that a whale lens has small apertures and it is more difficult to achieve a good picture with them than with a fast lens.
Well yes, Carl Zeiss Sonnar T * 4/180 sucks, because with
The picture here is neither “bad” or “good”. She has a large depth of field with a whale lens. It is because of her that the photos look “soapy”. There is absolutely nothing wrong with this for landscapes.
Accidentally clicked submit.
Well, yes, Carl Zeiss Sonnar T * 4/180 0 sucks, because its aperture is like a whale lens ... The aperture itself only affects the depth of field (well, shutter speed and / or sensitivity).
Please note that nothing has been written about contrast, it has only been written about juiciness and brightness. You can't compare lenses with different focal lengths - that's where the catch is with the Carl Zeiss Sonnar T * 4/180 and 18-55.
With low contrast, there are no rich saturated colors (unless, of course, you do not twist the saturation in the settings) ...
There is no word in the article about the focal length. It is said only if the aperture is small, then there will be no good frames.
Well, if you feel like it, then in the review on this site you are very well referred to the Mir-10A, which has the widest f / 3.5 aperture, like the whale lens. Of course, a 28 mm whale only opens before f / 4, but I do not think that 1/3 of a stop can seriously affect something.
I changed the article as amended. Thanks.
By the way, the iris diaphragm as in Stargate is in reality impossible.
First, the iris can never close completely. This is hampered by the finite thickness of the petals. And the more petals, the larger the minimum diameter with the same thickness.
Secondly, in the film, the diaphragm was a few microns from the surface of the wormhole. Due to the same finite thickness of the petals, the diaphragm does not form a flat surface. Moreover, when closed, it acquires a certain taper. So in some places and in truth there could be microns, but in others the gap would inevitably amount to millimeters and even centimeters.
I took a poster with a diaphragm for the fictional Stargate only so that film lovers could easily imagine and remember what a diaphragm is.
And I have a Nikon coolpix s8100, and it’s not clear where to adjust the aperture, is it because I'm just starting to take photos? Or is there no such function?
This is due to the fact that this function is hidden in the camera settings. I highly recommend finding the diaphragm section in the manual.
Arkady, help me, please figure it out. I have a Helios-44-2 lens. At an f-number of 2, the aperture is small; at 16, the aperture is maximally large. Quite the opposite of what should be. Why is that? Thank you in advance!
Musya, your lens has a manual aperture ring (not a “jumping” aperture). There is a restrictive ring (it clicks) - put the diaphragm with it, and with the second ring you open and close the diaphragm. When you open it, focus (to make it bright in the viewfinder), close it all the way and press the button. So, the real value should be viewed on the restrictive ring, and not on the quick opening / closing ring of the diaphragm.
The text says:
>> To see how the images will look when the aperture is closed, you can sometimes use an Iris Tutor.
Right: repeater
Thanks. Refresh.
all understood thanks a lot)
thank you very much everything is clear)
Please help me figure it out. I am new to photography. I have a Nikon 7000 with a Nikkor 18-105mm 1: 3,5-5,6 lens. When the aperture is closed, that is, the hole is a small number F = 3.5. When the diaphragm is open, that is, the hole is a large number F = 5,6. Explain with the example of my lens how the aperture and focal length change due to a change in aperture.
The aperture is open when F / 3.5 (the number F is small), and closed when f / 5.6 (the number F is large), it is written about this in the article, just read it carefully. The aperture ratio changes in proportion to the square of the diaphragm change, which is also described in the article. From changing the aperture, the focal length does not change, the numbers F / (aperture) and f = (focal length) are not connected.
Thank you very much, Arkady. I carefully read the article and seemed to understand everything. And the question arose because when I took a picture in P mode (program auto mode) with an open aperture, F = 5.6 is displayed in the viewfinder, and when F = 3.5 is displayed with a closed aperture. Why is the opposite in the viewfinder?
Nothing like that, in the viewfinder the values are as they should be.
You know, Arkady, probably, I just did not correctly describe the situation with the diaphragm. I assumed the F / 3.5 value in the viewfinder with the aperture closed is when the lens is in the retracted position, I look into it and see a small hole, and when I extend the lens, I see a large hole in the F / 5,6 viewfinder. Now I understand that these holes at different positions of the lens do not give an estimate of the aperture. We can determine the size of the aperture (aperture) and, accordingly, determine the aperture ratio only at the moment of shooting, that is, when the aperture blades open. Do I understand correctly?
Basically - the aperture is closed at the time of shooting. But you are right that the size of the visible aperture at different positions of the lens does not give an estimate of the aperture
Thank you very much, Arkady. Now everything became clear to me. I will continue to study the characteristics and capabilities of my camera.
spasibo bolshoe what to stalo ponjatnee
Found on the website (online store) in the lens description: Maximum aperture 16 and Minimum aperture 1.8. Naturally, I became interested, because it seems to be the other way around.
The site had a diaphragm number.
I'm confused.
I didn’t understand the f / 3.5-5.6 values are on the lens; say that you can compress the aperture only up to 5.6 and open it at just 3.5 ??? But what about the f22 values? Does it depend on the lens? Sorry for the stupid question))
Only the maximum aperture of f / 3.5-5.6 for the lens is indicated on the lens. 3.5 is for wide angle, 5.6 is for narrow angle (for maximum zoom). You can close up to F22 without problems
I noticed that if I manually select a pair of shutter speed and aperture from the flashlight (the pin is not at 0, it rolls over) the photos turn out to be noisy even at low ISO 800. Canon 40D in this case. Why would this be?
For Canon 40d, ISO 800 is far from low. They are also noisy because the shadow zone is underexposed.
Thank you :)
Hello, the Nikon D90 camera, with a standard KIT lens, I photograph in the room, in some places dim lights, I tried to set the portrait to AUTO and so on, in the manual I tried the F6.3 1 \ 60 and F 7.1 1 \ 8 modes as F3.5 1 \ 60 ISO I tried in auto mode and just in the 200 manual, I can’t achieve clarity, sharpness dances then it’s good in soap. How to be what's wrong ? I also work with flash. I even tried AUTO mode, a lot of noise. Can you tell me what I'm doing wrong? What to look for? Thanks.
Try the aperture priority at f / 8.0, remove the ISO 200 from the tripod by timer or using the remote control.
Hello. I can’t understand anything at all in the FujiFilm FinePix HS25 Black. I can not adjust the clarity of pictures. Everything is blurry. Help in the settings? You are welcome.
Hello. Usually, when using auto mode (green mode), the camera should take good sharp pictures, especially with the flash. Try to shoot with a flash, otherwise you need to delve into the instructions or hand over the camera under warranty.
Hello, Arkady. Tell me, please, are there digital compacts (soap dishes) in the modern world with the diaphragm mechanism as such? On many compact cameras, you can set the aperture value at will, but the process of dosing light occurs due to an electronically controlled neutral filter (if the previous sources did not deceive me), and the hole itself, as it was completely open, remains.
Why is this needed:
I choose a compact camera, I settled on Nikon p310 (high-aperture camera F1.8) and Nikon J1 (mirrorless or system camera with interchangeable lenses). I am sure that J1 has the aperture itself, more precisely - in 1Nikkor lenses. But with a high-aperture camera it is somehow completely incomprehensible whether it will be possible to achieve from it either a blurred background or a ringing sharp image when the f-number is changed? Thank you very much for your answer.
I myself am interested in this question, but it’s not strange with soap dishes, I don’t come across and I can’t give an exact answer on diaphragm control.
Arkady, your topics are cool, briefly and clearly ... I've got my son on a photo. Do you have this material on the website in PDF? to print to him.
No, the site makes money for its hosting by advertising in the sidebars, it's not profitable for me to create PDF files. By the way, there are a lot of 'friends' who are downloading my site, thereby creating an extra load on the site for me - please do not.
a kak nastroit diafragmu nikon d7000 nikkor 18-105mm 3.5-5.6))) ??? otkuda otkrivayetsya ili zakrivayetsya))) navichok ya, izvinyayus za glupiy vopros
Mode 'A' on the selection wheel by the camera.